Showing papers in "Diabetologia in 1998"

Is Type II diabetes mellitus a disease of the innate immune system

Abstract: Type II (non-insulin-dependent) diabetes mellitus is associated with increased blood concentrations of markers of the acute-phase response, including sialic acid, α-1 acid glycoprotein, serum amyloid A, C-reactive protein and cortisol, and the main cytokine mediator of the response, interleukin-6. The dyslipidaemia common in Type II diabetes (hypertriglyceridaemia and low serum levels of HDL cholesterol) is also a feature of natural and experimental acute-phase reactions. We review evidence that a long-term cytokine-mediated acute-phase reaction occurs in Type II diabetes and is part of a wide-ranging innate immune response. Through the action of cytokines on the brain, liver, endothelium, adipose tissue and elsewhere, this process could be a major contributor to the biochemical and clinical features of metabolic syndrome X (glucose intolerance, dyslipidaemia, insulin resistance, hypertension, central obesity, accelerated atherosclerosis) but also provides a mechanism for many other abnormalities seen in Type II diabetes, including those in blood clotting, the reproductive system, metal ion metabolism, psychological behaviour and capillary permeability. In the short-term, the innate immune system restores homeostasis after environmental threats; we suggest that in Type II diabetes and impaired glucose tolerance long-term lifestyle and environmental stimulants, probably in those with an innately hypersensitive acute-phase response, produce disease instead of repair. [Diabetologia (1998) 41: 1241–1248]

Increasing prevalence of Type II diabetes in American Indian children

Abstract: Until recently, Type II diabetes was considered rare in children. The disease is, however, increasing among children in populations with high rates of Type II diabetes in adults. The prevalence of Type II diabetes was determined in 5274 Pima Indian children between 1967 and 1996 in three 10-year time periods, for age groups 5-9, 10-14 and 15-19 years. Diabetes was diagnosed using World Health Organisation criteria, based on an oral glucose tolerance test. The prevalence of diabetes increased over time in children aged 10 years and over: in boys from 0 % in 1967-1976 to 1.4% in 1987-1996 in the 10-14 year old age group, and from 2.43% to 3.78% for age group 15-19 and in girls from 0.72 % in 1967-1976 to 2.88 % in 1987-1996 in the 10-14 year old age group, and from 2.73 % to 5.31 % for age group 15-19 years. Along with the increase in the prevalence of Type II diabetes (p < 0.0001), there was an increase in weight (calculated as percentage of relative weight, p < 0.0001), and in frequency of exposure to diabetes in utero (p < 0.0001). The increasing weight and increasing frequency of exposure to diabetes in utero accounted for most of the increase in diabetes prevalence in Pima Indian children over the past 30 years. Type II diabetes is now a common disease in American Indian children aged 10 or more years and has increased dramatically over time, along with increasing weight. A vicious cycle related to an increase in the frequency of exposure to diabetes in utero appears to be an important feature of this epidemic.

Dipeptidyl peptidase IV resistant analogues of glucagon-like peptide-1 which have extended metabolic stability and improved biological activity

Abstract: Glucagon-like peptide 1 (GLP-1) has great potential in diabetes therapy due to its glucose-dependent stimulation of insulin secretion, but this is limited by its rapid degradation, primarily by dipeptidyl peptidase IV. Four analogues, N-terminally substituted with threonine, glycine, serine or alpha-aminoisobutyric acid, were synthesised and tested for metabolic stability. All were more resistant to dipeptidyl peptidase IV in porcine plasma in vitro, ranging from a t1/2 of 159 min (Gly8 analogue) to undetectable degradation after 6 h (Aib8 analogue; t1/2 for GLP-1 (7-36) amide, 28 min). During i. v. infusion in anaesthetised pigs, over 50% of each analogue remained undegraded compared to 22.7 % for GLP-1 (7-36) amide. In vivo, analogues had longer N-terminal t1/2 (intact peptides: means, 3.3-3.9 min) than GLP-1 (7-36) amide (0.9 min; p Gly8 > Ser8 > Thr8). N-terminal modification of GLP-1 confers resistance to dipeptidyl peptidase IV degradation. Such analogues are biologically active and have prolonged metabolic stability in vivo, which, if associated with greater potency and duration of action, may help to realise the potential of GLP-1 in diabetes therapy.

Angiotensin II and the endocrine pancreas: Effects on islet blood flow and insulin secretion in rats

Abstract: Angiotensin II and the endocrine pancreas: effects on islet blood flow and insulin secretion in rats

Missense mutations in the pancreatic islet beta cell inwardly rectifying K+ channel gene (KIR6.2/BIR): a meta-analysis suggests a role in the polygenic basis of Type II diabetes mellitus in Caucasians.

Abstract: The K+ inwardly rectifier channel (KIR) is one of the two sub-units of the pancreatic islet ATP-sensitive potassium channel complex (I(KATP)), which has a key role in glucose-stimulated insulin secretion and thus is a potential candidate for a genetic defect in Type II (non-insulin-dependent) diabetes mellitus. We did a molecular screening of the KIR6.2 gene by single strand conformational polymorphism (SSCP) and direct sequencing in 72 French Caucasian Type II diabetic families. We identified three nucleotide substitutions resulting in three amino acid changes (E23K, L270V and 1337V), that have also been identified in other Caucasian Type II diabetic subjects. These variants were genotyped in French cohorts of 191 unrelated Type II diabetic probands and 119 normoglycaemic control subjects and association studies were done. The genotype frequencies of the L270V and 1337V variants were not very different between Type II diabetic subjects and control groups. In contrast, analysis of the E23K variant showed that the KK homozygocity was more frequent in Type II diabetic than in control subjects (27 vs 14%, p = 0.015). Analyses in a recessive model (KK vs EK/EE) tended to show a stronger association of the K allele with diabetes (p = 0.0097, corrected p-value for multiple testing < 0.02). The data for the E23K variant obtained here and those obtained from three other Caucasian groups studied so far were combined and investigated by meta-analysis. Overall, the E23K variant was found to be significantly associated with Type II diabetes (0.001 < or = p < or = .00106, corrected p-values for multiple testing p < or = 0.01). This study shows that KIR6.2 polymorphisms are frequently associated with Type II diabetes in French Caucasians. Furthermore, a meta-analysis combining different Caucasian groups suggests an significant role of KIR6.2 in the polygenic context of Type II diabetes.

Insulin-induced vasodilatation: physiology or pharmacology?

Abstract: Ever since the pioneering studies performed by Andres, Rabinowitz and Zierler 40 years ago [1‐4], investigators interested in insulin action considered insulin resistance in obesity [3], hypertension [5], insulin-dependent (IDDM) [6] and non-insulin-dependent diabetes mellitus (NIDDM) [7] to be primarily a problem of glucose utilization in peripheral tissues, which was independent of glucose delivery. However, a series of studies published since 1990, notably by Alain Baron and his associates, demonstrated that under certain conditions insulin increased leg blood flow [8], and that defects in this action of insulin were likely to contribute significantly to insulin resistance of glucose uptake caused by obesity [8], hypertension [9], IDDM [10] and NIDDM [11]. These latter findings contradicted the vast majority of earlier data and created a controversy regarding the role, or lack thereof, of defects in insulin stimulated blood flow in the pathogenesis of insulin resistance of glucose uptake. It is the purpose of the ensuing review to try to discuss the reasons for the discrepant findings. We will first review a series of studies performed in our own laboratory, which were designed to resolve the “flow controversy”. These studies examined whether the blood flow response to insulin is influenced by: i) the method used to quantitate blood flow; ii) the anatomical location of the flow measurement; iii) dose and duration of the insulin exposure; iv) individual factors such as limb muscularity, physical fitness and endothelial function, defined as the ability to vasodilate in response to nitric oxide (NO) synthesis-dependent vasodilatators. We will try to establish whether this physiological knowledge helps to explain the discrepancies observed in the studies performed in various insulin resistant conditions. We will then review the studies directly testing the hypothesis that an increase in blood flow enhances glucose uptake, and discuss the possibility that various vasoactive agents may change total flow similarly but have distinct effects on flow distribution. Finally, we will review studies relating insulin’s vascular effects to endothelial function, which have opened up an entirely new perspective for understanding how insulin resistance might predispose to vascular disease.

Association between poor glucose tolerance and rapid post natal weight gain in seven-year-old children

Abstract: A number of studies have shown that glucose tolerance falls with decreasing birth weight and that people with low birth weight and high body mass index (BMI) as adults are those at greatest risk of developing Type II (non-insulin-dependent) diabetes mellitus. No such studies have been carried out in African populations. Therefore we investigated the relation between glucose tolerance and birth weight in a group of 7-year-old black South Africans for whom longitudinal anthropometric data were available. Oral glucose tolerance tests (OGTTs) were carried out on 152 subjects and inverse correlations were found between birth weight and the total amount of insulin secreted during the first 30 min (r = –0.19, p = 0.04) and last 90 min (r = –0.19, p = 0.04) of the oral glucose tolerance test and also between birth weight and the 30 min glucose concentrations (r = –0.20, p = 0.02). Children born with low birth weights but who had high weights at 7 years had higher insulin concentrations and indices of obesity compared with those with low birth weights and low weights at 7 years. There were also positive correlations between weight velocity and BMI (r = 0.24, p = 0.02) and weight velocity and insulin resistance (r = 0.18, p = 0.04) as measured using homeostasis model assessment (HOMA). Thus, low birth weight in conjunction with rapid childhood gains in weight especially as subcutaneous fat, produces poor glucose tolerance in 7-year-old children and can make them susceptible to the development of Type II diabetes later in life. [Diabetologia (1998) 41: 1163–1167]

Meta-analysis of association of insertion/deletion polymorphism of angiotensin I-converting enzyme gene with diabetic nephropathy and retinopathy.

Abstract: An insertion/deletion (I/D) polymorphism in the angiotensin-converting enzyme (ACE) gene has repeatedly been shown to be associated with ischaemic heart disease, but the association of this genetic marker with diabetic microangiopathy is controversial. To assess the association of the genotypes with the development of diabetic nephropathy or retinopathy, we performed a meta-analysis of data from the literature, using Mantel-Haenszel method followed by the Breslow-Day test for assessing homogeneity among data. In a total of 4773 diabetic patients from 18 studies with (n = 2495) and without (n = 2278) renal complications, the D allele was significantly associated with diabetic nephropathy (p < 0.0001) in a dominant model (summary odds ratio 1.32, 95 % confidence interval: 1.15 to 1.51). There was no significant evidence against homogeneity of the odds ratios (χ2 = 18.9, 20 df; p = 0.53). The association was significant both in non-insulin-dependent (p < 0.005) and in insulin-dependent diabetes mellitus (p < 0.05). Likewise, in a total of 2010 diabetic patients with (n = 1008) and without (n = 1002) retinopathy, there was no association of the I/D polymorphism with diabetic retinopathy. These data suggest that the ACE I/D polymorphism affects the risk for diabetic nephropathy, but not for diabetic retinopathy. [Diabetologia (1998) 41: 47–53]

Beta-cell mass and proliferation following late fetal and early postnatal malnutrition in the rat.

Abstract: We have recently shown that maternal food restriction during late pregnancy in rats decreased beta-cell mass in the offspring at birth, without altering beta-cell proliferation. The aim of the present work was to determine: 1) whether sustained maternal undernutrition until weaning (R group) more dramatically alters beta-cell mass in the offspring and if normal food supply from weaning until adulthood could reverse the deleterious effects and; 2) if altered beta-cell proliferation was responsible for the decreased beta-cell mass. Beta-cell fraction and proliferative capacity were determined during the suckling period and at adult age after ad libitum feeding from weaning in the R animals and in age-matched controls (C group). At day 21, the offspring born and nursed by food-restricted mothers (R animals) showed a 66 % reduction in beta-cell mass and number, which did not increase from birth to weaning, although beta-cell proliferation remained normal. At 3 months of age, R animals had 35 % decreased beta-cell fraction, with a 50 % decrease in the head of the pancreas. In that area, beta-cell proliferation was similar to that of the controls. In the tail of the pancreas, beta-cell fraction was only slightly impaired but beta-cell proliferation was increased by 37 %, as compared with the controls. This increase was associated with a shift in islet size distribution towards medium and large islets compared with the head of pancreas from these R animals. No regional variations of beta-cell fraction, proliferation or islet size distribution were observed in adult control animals. In conclusion, prolonged malnutrition until weaning impairs beta-cell development but not beta-cell proliferation. Subsequent re-nutrition is followed by increased beta-cell proliferation but this is insufficient to fully restore beta-cell mass. [Diabetologia (1998) 41: 1114–1120]

Regional difference in insulin inhibition of non-esterified fatty acid release from human adipocytes: relation to insulin receptor phosphorylation and intracellular signalling through the insulin receptor substrate-1 pathway.

Abstract: Increased mobilization of non-esterified fatty acids (NEFA) from visceral as opposed to peripheral fat depots can lead to metabolic disturbances because of the direct portal link between visceral fat and the liver. Compared with peripheral fat, visceral fat shows a decreased response to insulin. The mechanisms behind these site variations were investigated by comparing insulin action on NEFA metabolism with insulin receptor signal transduction through the insulin receptor substrate-1 (IRS-1) pathway in omental (visceral) and subcutaneous human fat obtained during elective surgery. Insulin inhibited lipolysis and stimulated NEFA re-esterification. This was counteracted by wortmannin, an inhibitor of phosphaditylinositol (PI) 3-kinase. The effects of insulin on antilipolysis and NEFA re-esterification were greatly reduced in omental fat cells. Insulin receptor binding capacity, mRNA and protein expression did not differ between the cell types. Insulin was four times more effective in stimulating tyrosine phosporylation of the insulin receptor in subcutaneous fat cells (p < 0.001). Similarly, insulin was two to three times more effective in stimulating tyrosine phosphorylation of IRS-1 in subcutaneous fat cells (p < 0.01). This finding could be explained by finding that IRS-1 protein expression was reduced by 50 ± 8 % in omental fat cells (p < 0.01). In omental fat cells, maximum insulin-stimulated association of the p85 kDa subunit of PI 3-kinase to phosphotyrosine proteins and phosphotyrosine associated PI 3-kinase activity were both reduced by 50 % (p < 0.05 or better). Thus, the ability of insulin to induce antilipolysis and stimulate NEFA re-esterification is reduced in visceral adipocytes. This reduction can be explained by reduced insulin receptor autophosphorylation and signal transduction through an IRS-1 associated PI 3-kinase pathway in visceral adipocytes. [Diabetologia (1998) 41: 1343–1354]

Adipose tissue secretion of plasminogen activator inhibitor-1 in non-obese and obese individuals

Abstract: High plasma plasminogen activator inhibitor-1 (PAI-1) activity is a frequent finding in obesity, and both PAI-1 and obesity are risk factors for cardiovascular disease. To study the mechanisms underlying increased PAI-1 levels in obese individuals, gene expression and secretion of PAI-1 were measured in human abdominal subcutaneous adipose tissue. A total of 32 obese, otherwise healthy subjects and 10 never-obese healthy subjects with a body mass index (BMI) of 42.6 ± 1.2 and 24.3 ± 1.9 kg/m2 (mean ± SEM), respectively, were investigated. Plasma PAI-1 activity, adipose tissue PAI-1 secretion and adipocyte PAI-1 mRNA levels were increased sevenfold (p < 0.0001), sixfold (p < 0.0001) and twofold (p < 0.05), respectively, in the obese group. There were clear associations between adipose tissue secretion of PAI-1 and PAI-1 mRNA levels on the one hand and fat cell volume on the other (r = 0.68, p < 0.0001 and r = 0.51, p < 0.01, respectively, in the obese group). PAI-1 mRNA levels were also related to the amount of PAI-1 secreted among obese individuals (r = 0.31, p = 0.09). It is concluded that adipose tissue secretes significant amounts of PAI-1, that PAI-1 secretion from adipose tissue is increased in obesity, and that PAI-1 secretion is related to the lipid content and cell volume of fat cells. Plasma PAI-1 activity is elevated in obesity, at least in part due to increased gene expression in adipocytes, which, in turn, enhances PAI-1 secretion from adipose tissue. [Diabetologia (1998) 41: 65–71]

Regulation by cytokines of the inducible nitric oxide synthase promoter in insulin-producing cells

Abstract: Cytokines could contribute to beta-cell damage in Type I diabetes mellitus. The radical nitric oxide, generated by the inducible form of nitric oxide synthase (iNOS), is a potential mediator of cytokine-induced beta-cell dysfunction. In rat pancreatic islets and insulin-producing cell lines, interleukin-1beta (IL-1beta) induces expression of iNOS mRNA and increases NO production, an effect potentiated by interferon-gamma (IFN-gamma). In human islet cells both IL-1beta and IFN-gamma are required for iNOS expression. We have shown previously that both the transcription factors nuclear factor-kappaB (NF-kappaB) and interferon regulatory factor-1 (IRF-1) are activated by cytokines in rodent and human islets but there is no direct information on the regulation of the iNOS promoter in insulin-producing cells. We presently investigated the effects of cytokines on iNOS transcriptional regulation in both rat insulin-producing RINm5F cells and in primary FACS-purified rat beta cells. Transient transfection experiments with the 1.5-kb rat promoter region and 5' deletants of it showed that a distal region extending up to -1002 bp, and containing a distal and a proximal nuclear factor-kappaB (NF-kappaB) binding site, a gamma-interferon activated site (GAS) and two adjacent IFN-stimulated response elements (ISRE), is required for IL-1beta induction and IFN-gamma potentiation of iNOS activation. Site-mutation analysis showed that both the distal and proximal NF-kappaB and GAS are necessary for IL-1beta-induced iNOS expression in RINm5F cells. In these cells IFN-gamma potentiation is mostly mediated by GAS and ISRE, suggesting a role for the IFN-gamma-induced transcription factors Stat1alpha (which binds GAS) and IRF-1 (which binds ISRE), which may cooperate with NF-kappaB induced by IL-1beta for iNOS activation. In primary beta cells both NF-kappaB binding sites are required for IL-1beta-induced iNOS promoter activation. In these cells IFN-gamma neither increased IL-1beta-induced iNOS promoter activity nor iNOS mRNA expression but it induced a twofold increase in NO production. The present results unveiled the nature of the promoter binding sites necessary for iNOS expression in rodent beta cells. This information could be relevant for the development of new strategies aimed at preventing cytokine-induced iNOS expression and consequent beta-cell damage.

Incidence of cardiovascular disease in Type 1 (insulin-dependent) diabetic subjects with and without diabetic nephropathy in Finland.

Abstract: This study evaluates the impact of diabetic nephropathy on the incidence of coronary heart disease, stroke and any cardiovascular disease in the Finnish population, which has a high risk of Type 1 (insulin-dependent) diabetes mellitus and cardiovascular disease. We performed a prospective analysis of the incidence of coronary heart disease, stroke and cardiovascular disease in all Type 1 subjects in the Finnish Type I diabetes mellitus register diagnosed before the age of 18 years between 1 January 1965 and 31 December 1979 nationwide. The effect of age at onset of diabetes, attained age at the end of follow-up, sex, diabetes duration and of the presence of diabetic nephropathy on the risk for cardiovascular disease was evaluated. Cases of nephropathy, coronary heart disease, stroke and all cardiovascular diseases were ascertained from the nationwide Finnish Hospital Discharge Register and National Death Register using computer linkage with the Type I diabetes mellitus register. Of the 5148 Type 1 diabetic patients followed up, 159 had a cardiovascular event of which 58 were coronary heart diseases, 57 stroke events and 44 other heart diseases. There were virtually no cases of cardiovascular disease before 12 years diabetes duration. The cumulative incidence of cardiovascular disease by the age of 40 years was 43% in Type 1 diabetic patients with diabetic nephropathy, compared with 7% in patients without diabetic nephropathy, similarly in men and women. The relative risk for Type 1 diabetic patients with diabetic nephropathy compared with patients without diabetic nephropathy was 10.3 for coronary heart disease, 10.9 for stroke and 10.0 for any cardiovascular disease, similarly in men and women. The presence of nephropathy in Type I diabetic subjects increases not only the risk of coronary heart disease, but also of stroke by tenfold.

Extra-insular beta cells associated with ductules are frequent in adult human pancreas.

Abstract: Routine immunohistochemical analysis of human donor pancreata indicated the frequent occurrence of single insulin-immunoreactive cells. In a quantitative analysis of nine organs consecutively recruited from adult donors, 15 percent of all beta cells were found in units with a diameter less than < 20 μm and without associated glucagon-, somatostatin-, or pancreatic polypeptide cells. These single beta-cell units are located in or along ductules, from which they appear to bud as previously noticed in fetal and neonatal organs. They contain significantly smaller beta cells than endocrine aggregates with a larger diameter. The use of ductal cell markers such as cytokeratin 19, carbonic anhydrase-II and carbohydrate antigen 19.9 identified a close topographical association between ductal cells and budding beta cells; it also indicated that pancreatic lobules are composed of nearly one third ductal cells. The presence of Ki67 proliferation marker-immunoreactive ductal cells (0.05 %) and absence of Ki67-immunoreactive budding beta cells is compatible with the view that beta-cell neogenesis depends on ductal cell proliferation and differentiation. The high proportion of budding beta cells in the adult human pancreas suggests the presence of numerous loci with a potential for beta-cell neogenesis. [Diabetologia (1998) 41: 629–633]

Plasma homocysteine is related to albumin excretion rate in patients with diabetes mellitus: a new link between diabetic nephropathy and cardiovascular disease?

Abstract: The high risk of cardiovascular disease in patients with diabetes mellitus, particularly in those with nephropathy, is not completely explained by classical risk factors. A high plasma homocysteine concentration is an independent risk factor for cardiovascular disease but information on its association with diabetes is limited. Fasting homocysteine concentrations were measured in the plasma of 165 diabetic patients (75 with insulin-dependent [IDDM]; 90 with non-insulin-dependent diabetes [NIDDM]) and 56 non-diabetic control subjects. Other measurements included the prevalence of diabetic complications, glycaemic control, lipid and lipoprotein levels, vitamin status and renal function tests. Patients with NIDDM had higher homocysteine levels than control subjects, whereas IDDM patients did not (9.2 ± 4.5 vs 7.7 ± 2 μmol/l, p < 0.01; and 7.0 ± 3 vs 7.4 ± 2 μmol/l, NS). Univariate correlations and multiple regression analysis showed albumin excretion rate to be the parameter with the strongest independent association with homocysteine. Patients with both types of diabetes and nephropathy had higher plasma homocysteine concentrations than those without nephropathy. Increases of homocysteine in plasma were related to increases in the severity of the nephropathy. Fasting hyperhomocysteinaemia was considered as the mean of the plasma homocysteine for all control subjects (7.5 ± 2.1 μmol/l) + 2 SD (cut-off =11.7 μmol/l). Nephropathy was present in 80 % of diabetic patients with fasting hyperhomocysteinaemia. In conclusion, increases in fasting homocysteine in diabetic patients are associated with increased albumin excretion rate, especially in those with NIDDM, thus providing a potential new link between microalbuminuria, diabetic nephropathy and cardiovascular disease. [Diabetologia (1998) 41: 684–693]

The prevalence of clinical diabetic polyneuropathy in Spain: a study in primary care and hospital clinic groups

Abstract: A multiregional cross-sectional study of clinical diabetic polyneuropathy (DPN) was carried out among Spanish diabetes patients using a standard system for scoring symptoms and signs of polyneuropathy. The main patient sample comprised 2 644 patients (54.7 % women) aged 15–74 years (mean 57.2 ± 0.3 years), 86.9 % of whom had Type II (non-insulin-dependent) diabetes mellitus and 29.4 % were attending hospital clinics. Mean duration of diabetes since diagnosis was 10.2 ± 0.2 years. The prevalence of DPN was 22.7 % (95 % confidence interval 21.2–24.3 %) in the whole sample, 12.9 % (9.4–16.5 %) among patients with Type I (insulin-dependent) diabetes mellitus and 24.1 % (22.4–25.9 %) among patients with Type II diabetes; there was no significant difference in prevalence between men and women. Prevalence increased with age (from 30 years). In a supplementary sample of 161 diabetic patients aged 75 to 79 years (excluded from the main sample to prevent confusion between diabetes-induced and ageing-induced neuropathies), prevalence was 37.8 %. Ninety-three patients (3.3 %) had or had had foot ulcers and 21 of these 93 (0.7 %) had undergone amputation; 90.8 % of ulcerated patients had Type II diabetes, and 54 % had DPN (in most cases with loss of perception of vibration), as against a prevalence of DPN of 19.9 % among patients without ulcers. We conclude that nearly a quarter of Spanish diabetic patients have DPN; that over 90 % of DPN patients have Type II diabetes; that the prevalence of DPN increases with age and with the duration of the disease, and that the risk of foot ulcers among DPN patients is about three times the risk among diabetic patients without DPN. We accordingly emphasize the responsibility of primary care physicians to try to prevent diabetic foot lesions by early diagnosis of DPN. [Diabetologia (1998) 41: 1263–1269]

No excess 12-year mortality in men with impaired glucose tolerance who participated in the Malmö Preventive Trial with diet and exercise.

Abstract: Impaired glucose tolerance (IGT) is associated with increased mortality due to ischaemic heart disease (IHD), but as it is not known whether this excess mortality can be reduced by preventing or delaying the development of non-insulin-dependent diabetes mellitus (NIDDM), a long-term NIDDM prevention trial of dietary counselling and physical exercise was launched at Malmo, Sweden, the 12-year follow-up of which is reported here. At 12-year follow-up of 6956 men who underwent health screening at 48 years of age, an IGT intervention group (n = 288) who participated in a long-term NIDDM prevention programme were compared with an IGT non-randomised routine treatment group (n = 135), a diabetic group (n = 144), and the remainder, the normal glucose tolerance (NGT) group (n = 6389). The variables studied included the levels of blood glucose, plasma insulin, blood pressure, blood lipids, lung function and maximum oxygen uptake. Subjects with IGT were characterised by overweight, poor vital capacity, hypertension, hypertriglyceridaemia and hyperinsulinaemia. The mortality rate in the IGT intervention group was similar to that in the NGT group (6.5 vs 6.2 per 1000 person years at risk) and lower than that in the IGT routine treatment group (6.5 vs 14.0, p = 0.009). In the two IGT groups taken together, intervention but not body mass index, systolic blood pressure, smoking, cholesterol or the 2-h glucose level predicted mortality. Systolic blood pressure was a predictor of IHD mortality among IGT subjects; and in the cohort as a whole, body mass index, systolic blood pressure, hypercholesterolaemica, diabetes and smoking were predictors of IHD mortality. The findings suggest that a long-term intervention programme, with an emphasis on lifestyle changes, including dietary counselling and physical exercise, will reduce mortality in subjects with IGT who are at an increased risk of both developing NIDDM and of premature death due to IHD and other causes. [Diabetologia (1998) 41: 1010–1016]

IA-2 antibodies - a sensitive marker of IDDM with clinical onset in childhood and adolescence

Abstract: To study the relationship of IA-2 antibodies (IA-2A) to other autoantibodies and genetic risk markers in insulin-dependent diabetes mellitus (IDDM), 758 children and adolescents younger than 15 years of age (mean age 8.4 years) with newly diagnosed diabetes were analysed for IA-2A, GAD antibodies (GADA) and insulin autoantibodies (IAA) with radiobinding assays, for islet cell antibodies (ICA) with immunofluorescence and for HLA DR alleles by serology. IA-2A were detected in 85.9% of cases with no association with gender or age. An overwhelming majority of the patients (71.3%) tested positive for three or more antibodies, and 90.7% for at least two. Fifty-four subjects (7.1%) had one antibody detectable, whereas only 2.1% of the patients tested negative for all four. A higher proportion of patients was positive for IA-2A and/or GADA than for ICA alone (95.5 vs 84.2%, p < 0.001). The prevalence and level of IA-2A were increased in cases carrying HLA DR4/non-DR3 compared with other DR combinations. The results indicate that almost all patients with newly diagnosed childhood IDDM can be identified by screening with these four autoantibodies. The combination of IA-2A and/or GADA had a higher sensitivity for IDDM than ICA alone. The close association between IA-2A and HLA DR4, the strongest single allele predisposing to IDDM, suggests that IA-2A may be a more specific marker of beta-cell destruction than GADA, which have been shown to associate with the DR3 allele and thyroid autoimmunity.

Obesity, diabetes and the central nervous system

Abstract: Nearly 25 years ago, one of us wrote a collaborative review entitled “Obesity and Diabetes, the Odd Couple” [1]. At that time we pointed out that obesity was a risk factor for diabetes mellitus, despite the fact that most obese people do not have and never will develop diabetes. We also pointed out that obesity is associated with insulin resistance and hyperinsulinaemia, whereas in the non-obese, diabetes is characterized by hypoinsulinaemia and hyperglycaemia. We asked, how is it that such different syndromes interact so closely? We concluded that while these two syndromes are likely to have independent risk factors and mechanisms, their known interactions made it likely that shared metabolic defects are involved in their pathogenesis. We concluded that further studies into the pathophysiology of these syndromes were needed to explain this apparently paradoxical asso

Oxidative stress measurement by in vivo electron spin resonance spectroscopy in rats with streptozotocin-induced diabetes

Abstract: Enhanced oxidative stress in diabetic patients may contribute to the pathogenesis of diabetic angiopathy. We have recently developed a method to determine the electron spin resonance (ESR, electron paramagnetic resonance; EPR) of reactive oxygen species and free radicals in vivo, using the nitroxide derivative, carbamoyl-PROXYL as a probe. In this study, diabetes was induced in Wistar rats by streptozotocin (STZ) injection (65 mg/kg, body weight, intravenously). Two, 4, and 8 weeks later, the animals received carbamoyl-PROXYL (300 nmol/g, intravenously), and ESR was measured at the upper abdominal level at a frequency of 300 MHz. The intensity of the carbamoyl-PROXYL ESR signal decreased gradually after the injection, and the spin clearance rate was determined over the first 5 min. At all time points, the spin clearance rate was significantly greater in the diabetic rats than in control rats. Moreover, the spin clearance rate in the diabetic rats was significantly correlated with urinary malondialdehyde (MDA) levels, which serve as a marker for lipid peroxidation. Daily treatment with 4 units neutral protamin Hagedorn (NPH) insulin for 4 weeks reduced the spin clearance rate in the diabetic rats. Simultaneous injection of carbamoyl-PROXYL and superoxide dismutase reduced the spin clearance rate in the diabetic rats in a dose-dependent manner. Injection of the antioxidant alpha-tocopherol (40 mg/kg, intraperitoneally) for 2 weeks restored the spin clearance rate in the diabetic rats without concomitant glycaemic restoration. These results suggest that a diabetic state enhances the generation of free radicals in vivo, and that both glycaemic control and antioxidant treatment can reduce this oxidative stress. Non-invasive in vivo ESR measurement may be useful for evaluating oxidative stress in diabetes.

Advanced glycation endproducts inhibit prostacyclin production and induce plasminogen activator inhibitor-1 in human microvascular endothelial cells.

Abstract: Several thrombogenic abnormalities are associated with diabetes. To investigate the underlying molecular mechanisms, we examined the effects of advanced glycation endproducts (AGE), non-enzymatically glycated protein derivatives, on the production of prostacyclin (PGI2), an anti-thrombogenic prostanoid, and of plasminogen activator inhibitor-1 (PAI-1), a fast-acting serine protease inhibitor of fibrinolysis, in human microvascular endothelial cells (EC). Firstly, AGE-bovine serum albumin (BSA) but not non-glycated BSA, was found to considerably decrease the production of PGI2 to about two-thirds of the control value. Secondly, quantitative reverse transcription-polymerase chain reaction showed that AGE-BSA increased the EC levels of mRNA coding for PAI-1, this being associated with a concomitant increase in the immunoreactive PAI-1 contents and the anti-fibrinolytic activity. Thirdly, the effects of AGE on PGI2 and PAI-1 syntheses in EC were found to be mediated by a receptor for AGE (RAGE) because antisense DNA against RAGE mRNA could reverse the AGE effects. Further, it was found that AGE decreased the intracellular cyclic AMP concentrations in EC and that cyclic AMP agonists such as dibutyryl cyclic AMP, forskolin and PGI2 analogue reduced the AGE-stimulated PAI-1 production, suggesting the involvement of cyclic AMP in the AGE-signalling pathway. The results thus suggest that AGE have the ability to cause platelet aggregation and fibrin stabilization, resulting in a predisposition to thrombogenesis and thereby contributing to the development and progression of diabetic vascular complications. [Diabetologia (1998) 41: 1435–1441]

Insulin-induced vasodilatation and endothelial function in obesity/insulin resistance. Effects of troglitazone.

Abstract: Insulin resistance is associated with a decreased vasodilator response to insulin. Because insulin's vasodilator effect is nitric oxide dependent, this impairment may reflect endothelial dysfunction. Troglitazone, an insulin-sensitiser, might thus improve insulin-dependent and/or endothelium-dependent vascular function in insulin resistant obese subjects. For 8 weeks, fifteen obese subjects were treated with either 400 mg troglitazone once daily or placebo, in a randomised, double-blind, cross-over design. At the end of each treatment period, we measured forearm vasodilator responses (plethysmography) to intra-arterial administered acetylcholine and sodium nitroprusside; insulin sensitivity and insulin-induced vascular and neurohumoral responses (clamp); vasoconstrictor responses to NC-monomethyl-L-arginine (L-NMMA) during hyperinsulinaemia; and ambulatory 24-h blood pressure (ABPM). Baseline data (placebo) of obese subjects were compared with those obtained in lean control subjects. Obese subjects were insulin resistant compared with leans (whole-body glucose uptake: 26.8+/-3.0 vs. 53.9+/-4.3 [tmol kgl min-, p < 0.001). Troglitazone improved whole-body glucose uptake (to 31.9+/-3.3 micromol x kg(-1) x min(-1) , p=0.028), and forearm glucose uptake (from 1.09+/-0.54 to 2.31+/-0.69 micromol dL(-1) x min(-1), p=0.006). Insulin-induced vasodilatation was blunted in obese subjects (percent increase in forearm blood flow (FBF) in lean 66.5+/-23.0%, vs. 10.1+/-11.3% in obese, p=0.04), but did not improve during troglitazone. Vascular responses to acetylcholine, sodium nitroprusside and L-NMMA did not differ between the obese and lean group, nor between both treatment periods in the obese individuals. In conclusion, in insulin resistant obese subjects, endothelial vascular function is normal despite impaired vasodilator responses to insulin. Troglitazone improved insulin sensitivity but it had no effects on endothelium-dependent and -independent vascular responses. These data do not support an association between insulin resistance and endothelial function.

Glucose tolerance and resistance to insulin-stimulated glucose uptake in men aged 70 years in relation to size at birth.

Abstract: Although several studies have shown that reduced size at birth predicts glucose intolerance and insulin resistance in adult life, the relation has been inconsistent and usually stronger for ponderal index than for birthweight. We examined glucose tolerance and insulin sensitivity (by the euglycaemic clamp method) in relation to size at birth in 709 men aged 69–73 years in Uppsala, Sweden. After adjusting for adult body mass index, prevalence of glucose intolerance (defined as diabetes or impaired glucose tolerance) was inversely related to birthweight. In men born at term, there was a positive monotonic relation of insulin sensitivity with birthweight, strongest in those who were overweight at age 70. This relation was reversed in men born before term (p = 0.005 for interaction between pre-term birth and birthweight effect). Glucose intolerance and insulin resistance showed inverted U-shaped relations with ponderal index, in contrast with the monotonic inverse relation seen in this cohort at earlier ages. This change in form of the relations was partly accounted for by selective loss to follow-up between ages 60 and 70 years. These results confirm that the association between reduced fetal growth and glucose intolerance is mediated through insulin resistance and depends upon an interaction with obesity in adult life. This relation is obscured when pre-term births are included. Failure to stratify by gestational age in previous studies could account for inconsistencies in the relations of insulin resistance and glucose intolerance to size at birth and for the detection of stronger associations with ponderal index than with birthweight. [Diabetologia (1998) 41: 1133–1138]

Implantation of standardized beta-cell grafts in a liver segment of IDDM patients: graft and recipient characteristics in two cases of insulin-independence under maintenance immunosuppression for prior kidney graft

Abstract: Islet allografts in insulin-dependent diabetic (IDDM) patients exhibit variable survival lengths and low rates of insulin-independence despite treatment with anti-T-cell antibodies and maintenance immunosuppression. Use of poorly characterized freshly isolated preparations makes it difficult to determine whether failures are caused by variations in donor tissue. This study assesses survival of standardized beta-cell allografts in C-peptide negative IDDM patients on maintenance immunosuppression following kidney transplantation and without receiving anti-T-cell antibodies or additional immunosuppression. Human islets were isolated from pancreatic segments after maximal 20 h cold-preservation. During culture, preparations were selected according to quality control tests and combined with grafts with standardized cell composition (≥ 50 % beta cells), viability ( ≥ 90 % ), total beta-cell number (1 to 2 · 106/kg body weight) and insulin-producing capacity (2 to 4 nmol · graft–1· h–1). Grafts were injected in a liver segment through the repermeabilized umbilical vein. After 2 weeks C-peptide positivity, four out of seven recipients became C-peptide negative; two of them were initially GAD65-antibody positive and exhibited a rise in titre during graft destruction. The other three patients remained C-peptide positive for more than 1 year, two of them becoming insulin-independent with near-normal fasting glycaemia and HbA1 c; they remained GAD65- and islet cell antibody negative. The three patients with surviving grafts presented a history of anti-thymocyte globulin therapy at kidney transplantation. Long-term surviving grafts increased C-peptide release following intravenous glucagon or oral glucose but not following intravenous glucose. Thus, cultured human beta-cells can survive for more than 1 year in IDDM patients on maintenance anti-rejection therapy for a prior kidney graft and without the need for an increased immunosuppression at the time of implantation. The use of functionally standardized beta-cell grafts helps to identify recipient and graft factors which influence their survival and metabolic effects. Insulin-independence can be achieved by injection of 1.5 million beta-cells per kg body weight in a liver segment. These beta-cell implants respond well to adenylcyclase activators but poorly to glucose. [Diabetologia (1998) 41: 452–459]

Chronic diabetic complications in patients with MODY3 diabetes

Abstract: MODY3 diabetes, which is caused by a mutation in the hepatocyte nuclear factor-1α gene (HNF-1α) on chromosome 12, represents a relatively common monogenic form of diabetes in Finland Age at onset of the disease can vary from 10 to 60 years, but little is known about the natural course of the disease, particularly the development of diabetes-related chronic complications The availability of genetic markers now allows description of the clinical course of the disease In order to examine the prevalence of chronic diabetic complications in MODY3, we examined 57 carriers with HNF-1α mutations for the presence of micro- and macrovascular complications Thirty-four percent of the MODY patients had mild and 13 % had severe non-proliferative or proliferative retinopathy; this figure did not differ from the figures in insulin-dependent diabetes mellitus (IDDM) and non-insulin-dependent diabetes mellitus (NIDDM) patients matched for duration and glycaemic control but not for age Neither did the prevalence of microalbuminuria differ between MODY3 and IDDM or NIDDM patients (19 vs 24 and 23 %) Neuropathy was observed with the same frequency as previously reported in IDDM Hypertension was less frequent in MODY3 and IDDM than in NIDDM (245 and 19 vs 537 %; p < 0001) Coronary heart disease was more common in MODY3 than in IDDM (16 vs 45 %; p < 002) but less common than in the older NIDDM patients (333 %; p < 002) In a multiple logistic regression analysis, poor glycaemic control was an independent risk factor for retinopathy (p = 003), microalbuminuria (p < 004) and neuropathy (p = 003) In conclusion, microangiopathic complications are observed with the same frequency in patients with MODY3 diabetes as in IDDM and NIDDM and are strongly related to poor glycaemic control [Diabetologia (1998) 41: 467–473]

Autoantibodies associated with Type I diabetes mellitus persist after diagnosis in children

Abstract: To study the persistence of Type I (insulin-dependent) diabetes mellitus associated autoantibodies and their relation to genetic risk markers and clinical characteristics of the disease after clinical manifestation, serum samples were obtained from 90 children and adolescents at diagnosis and 2, 5 and 10 years later. The samples were analysed for islet cell antibodies (ICA) by immunofluorescence and for antibodies to glutamic acid decarboxylase (GADA), intracellular portion of the protein tyrosine phosphatase related IA-2 antigen (IA-2A) and insulin autoantibodies by specific radiobinding assays. Of the subjects tested 79 % were positive for IA-2A at diagnosis, 62 % for GADA, 81 % for ICA and 28 % for insulin autoantibodies, but the prevalence of IA-2A, GADA and ICA decreased substantially as a function of increasing duration of the disease (p < 0.05 or less), their levels following the same pattern (p < 0.001 for all three autoantibodies). Two thirds of the subjects still tested positive for at least one autoantibody specificity after the first 10 years of the disease and 42 % had two or three antibodies detectable. An increase over the initial antibody concentrations after the diagnosis was seen more often for GADA than for ICA (p < 0.001) or IA-2A (p < 0.05). In conclusion, autoantibodies associated with Type I diabetes appear to persist longer than expected after manifestation of the clinical disease, possibly due to small scale continuous beta-cell regeneration after diagnosis or to structural and/or functional mimicry between exogenous proteins and beta-cell antigens or both. [Diabetologia (1998) 41: 1293–1297]

Increased expression of endothelial cell nitric oxide synthase (ecNOS) in afferent and glomerular endothelial cells is involved in glomerular hyperfiltration of diabetic nephropathy

Abstract: The overproduction of nitric oxide (NO) is reported in the diabetic kidney and considered to be involved in glomerular hyperfiltration. The precise mechanism of NO production in the diabetic kidney is, however, not known. In this report, we compare the localization of endothelial cell nitric oxide synthase (ecNOS) isoform expression in the kidney tissue of streptozotocin (STZ)-induced diabetic rats and 5/6 nephrectomized rats and clarify the pivotal role of ecNOS for the glomerular hyperfiltration in the early stages of diabetic nephropathy. In diabetic rats, the diameters of afferent arterioles, the glomerular volume, creatinine clearance, and urinary NO2/NO3 were increased after the induction of diabetes. Efferent arterioles were, however, not altered. Insulin or L-NAME treatment returned the diameters of afferent arterioles, glomerular volume, creatinine clearance, and urinary NO2/NO3 to normal. The expression of ecNOS in afferent arterioles and glomeruli of diabetic rats increased during the early stages of the disease, but was not altered in efferent arterioles. Treatment with either insulin or L-NAME decreased ecNOS expression in afferent arterioles and in glomeruli. In contrast, the ecNOS expression was upregulated in both afferent and efferent arterioles and in the glomeruli of 5/6 nephrectomized rats, where the dilatation of afferent and efferent arterioles and glomerular enlargement were observed. Treatment with L-NAME ameliorated the ecNOS expression and dilatation of arterioles. We conclude that enhanced NO synthesis by ecNOS in afferent arterioles and glomerular endothelial cells in response to the hyperglycaemic state could cause preferential dilatation of afferent arterioles, which ultimately induces glomerular enlargement and glomerular hyperfiltration. [Diabetologia (1998) 41: 1426–1434]

Hyperinsulinaemia, dyslipaemia and cardiovascular risk in girls with a history of premature pubarche

Abstract: Girls with a history of premature pubarche, i. e. appearance of pubic hair before 8 years of age, show hyperinsulinism in response to an oral glucose tolerance test. As hyperinsulinaemia has a major role in dyslipaemia, and is considered an independent risk factor for cardiovascular disease, we assessed the patterns of plasma insulin concentration after a standard oral glucose tolerance test as well as fasting serum lipid, lipoprotein, and sex hormone-binding globulin concentrations in girls (n = 81) with premature pubarche compared with girls (n = 55) matched with them for stage and bone age to ascertain their metabolic states to identify those potentially at risk for the development of premature cardiovascular disease. Mean serum insulin concentrations were higher in patients at all pubertal stages, and associated with elevated serum triglyceride, very low density cholesterol and very low density triglyceride concentrations (p value range 0.04 to < 0.0001) but reduced sex hormone-binding globulin. Premature pubarche patients also displayed higher low density to high density lipoprotein cholesterol ratios compared with control subjects (p = 0.004 to 0.008). In conclusion, hyperinsulinaemia, decreased sex hormone-binding globulin concentrations and an unfavourable lipid pattern are common features in premature pubarche girls supporting the contention that atherogenic abnormalities composing the metabolic syndrome could start in childhood. To determine the clinical sequelae of such clustering of metabolic deviations, girls who were identified need to be followed up for the potential development of premature cardiovascular disease. [Diabetologia (1998) 41: 1057–1063]

Exaggerated secretion of glucagon-like peptide-1 (GLP-1) could cause reactive hypoglycaemia

Abstract: The plasma concentrations of the insulinotropic incretin hormone, glucagon-like peptide-1 (GLP-1) are abnormally high after oral glucose in partially gastrectomised subjects with reactive hypoglycaemia, suggesting a causal relationship. Because of the glucose-dependency of its effects, it is impossible to induce hypoglycaemia in normal subjects in the basal state by exogenous GLP-1, regardless of dose. To further assess the role of the incretin hormones in reactive hypoglycaemia, we reproduced the glucose and hormone profiles of the patients with reactive hypoglycaemia in 8 healthy volunteers in 4 separate protocols: 1) i. v. infusion of glucose (25 g) alone, 2) glucose together with i. v. GLP-1 infusion, and 3) and 4) glucose together with i. v. infusion of the other incretin hormone, glucose-dependent insulinotropic polypeptide (GIP), at two different infusion rates. The plasma glucose, GLP-1 and GIP concentrations (low dose) obtained were comparable with those of the patients. With GLP-1, infusion of a total of 33.4 ± 1.3 g glucose was required to obtain plasma glucose concentrations similar to those obtained by glucose infusion alone; with low GIP, 28.0 ± 1.2 g and with high GIP 38.4 ± 3.5 g. Insulin concentrations increased 10-fold with GLP-1 compared with i. v. glucose alone, but less with high and low GIP. In contrast, C-peptide concentrations were similar after GLP-1 and high GIP. After termination of i. v. glucose the lowest glucose concentrations were 4.5 (3.7–4.9) (median, range) for glucose alone; 2.4 (1.9–2.8) mmol/l with GLP-1; 3.7 (2.6–4.0) with low GIP and 3.3 (2.1–4.2 ) with high GIP. Thus, the exaggerated GLP-1 response to nutrients in patients with accelerated gastric emptying could be responsible for their high incidence of postprandial reactive hypoglycaemia. [Diabetologia (1998) 41: 1180–1186]

Effects of α-lipoic acid on neurovascular function in diabetic rats : interaction with essential fatty acids

Abstract: Elevated oxidative stress and impaired n-6 essential fatty acid metabolism contribute to defective nerve conduction velocity (NCV) and perfusion in diabetic rats, which may be corrected by free radical scavenger and γ-linolenic acid (GLA) treatments. α-Lipoic acid (LPA) has antioxidant actions and both LPA racemate (racLPA) and GLA treatments produced benefits in clinical neuropathy trials. The aims were to study LPA action on neurovascular function in diabetic rats and to investigate potential interactions for co-treatment with GLA and other essential fatty acids. After 6 weeks of diabetes, 2 weeks of racLPA treatment corrected 20 % sciatic motor and 14 % saphenous sensory NCV deficits. The ED50 for motor NCV restoration was approximately 38 mg kg–1 day–1. racLPA also corrected a 49 % diabetic deficit in sciatic endoneurial blood flow. R and S-LPA enantiomers were equipotent in correcting NCV and blood flow deficits. Treatment of diabetic rats with low doses (20 mg kg–1 day–1) of racLPA and GLA, while having modest effects on their own, showed evidence of marked synergistic action in joint treatment, completely correcting motor NCV and blood flow deficits. This was also noted for the novel compound, SOC0150, which contains equimolar proportions of LPA and GLA (ED50 9.3 mg kg–1 day–1, containing 3.5 mg LPA). NCV effects also showed marked synergism when racLPA:GLA ratios were varied over a 1:3–3:1 range. In contrast, a compound containing LPA and the n-3 component, docosahexaenoic acid, showed similar activity to LPA alone. Thus, LPA-GLA interactions yield drug combinations and compounds with an order of magnitude increase in efficacy against experimental diabetic neuropathy and are worthy of consideration for clinical trials. [Diabetologia (1998) 41: 390–399]