XI. STRATEGIES FOR IMPROVING DIABETES CARE D iabetes is a chronic illness that requires continuing medical care and patient self-management education to prevent acute complications and to reduce the risk of long-term complications. Diabetes care is complex and requires that many issues, beyond glycemic control, be addressed. A large body of evidence exists that supports a range of interventions to improve diabetes outcomes. These standards of care are intended to provide clinicians, patients, researchers, payors, and other interested individuals with the components of diabetes care, treatment goals, and tools to evaluate the quality of care. While individual preferences, comorbidities, and other patient factors may require modification of goals, targets that are desirable for most patients with diabetes are provided. These standards are not intended to preclude more extensive evaluation and management of the patient by other specialists as needed. For more detailed information, refer to Bode (Ed.): Medical Management of Type 1 Diabetes (1), Burant (Ed): Medical Management of Type 2 Diabetes (2), and Klingensmith (Ed): Intensive Diabetes Management (3). The recommendations included are diagnostic and therapeutic actions that are known or believed to favorably affect health outcomes of patients with diabetes. A grading system (Table 1), developed by the American Diabetes Association (ADA) and modeled after existing methods, was utilized to clarify and codify the evidence that forms the basis for the recommendations. The level of evidence that supports each recommendation is listed after each recommendation using the letters A, B, C, or E.

Standards of Medical Care in Diabetes

The worldwide epidemic of obesity has brought considerable attention to research aimed at understanding the biology of adipocytes (fat cells) and the events occurring in adipose tissue (fat) and in the bodies of obese individuals. Accumulating evidence indicates that obesity causes chronic low-grade inflammation and that this contributes to systemic metabolic dysfunction that is associated with obesity-linked disorders. Adipose tissue functions as a key endocrine organ by releasing multiple bioactive substances, known as adipose-derived secreted factors or adipokines, that have pro-inflammatory or anti-inflammatory activities. Dysregulated production or secretion of these adipokines owing to adipose tissue dysfunction can contribute to the pathogenesis of obesity-linked complications. In this Review, we focus on the role of adipokines in inflammatory responses and discuss their potential as regulators of metabolic function.

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Adipokines in inflammation and metabolic disease

More than any other cytokine family, the interleukin (IL)-1 family is closely linked to the innate immune response. This linkage became evident upon the discovery that the cytoplasmic domain of the IL-1 receptor type I is highly homologous to the cytoplasmic domains of all Toll-like receptors (TLRs). Thus, fundamental inflammatory responses such as the induction of cyclooxygenase type 2, increased expression of adhesion molecules, or synthesis of nitric oxide are indistinguishable responses of both IL-1 and TLR ligands. Both families nonspecifically affect antigen recognition and lymphocyte function. IL-1β is the most studied member of the IL-1 family because of its role in mediating autoinflammatory diseases. Although the TLR and IL-1 families evolved to assist in host defense against infection, unlike the TLR family, the IL-1 family also includes members that suppress inflammation, both specifically within the IL-1 family but also nonspecifically for TLR ligands and the innate immune response.

Immunological and Inflammatory Functions of the Interleukin-1 Family

Components of the immune system are altered in obesity and type 2 diabetes (T2D), with the most apparent changes occurring in adipose tissue, the liver, pancreatic islets, the vasculature and circulating leukocytes. These immunological changes include altered levels of specific cytokines and chemokines, changes in the number and activation state of various leukocyte populations and increased apoptosis and tissue fibrosis. Together, these changes suggest that inflammation participates in the pathogenesis of T2D. Preliminary results from clinical trials with salicylates and interleukin-1 antagonists support this notion and have opened the door for immunomodulatory strategies for the treatment of T2D that simultaneously lower blood glucose levels and potentially reduce the severity and prevalence of the associated complications of this disease.

Type 2 diabetes as an inflammatory disease.

ContextComplications of atherosclerosis cause most morbidity and mortality
in patients with diabetes mellitus. Despite the frequency and severity of
disease, proven medical therapy remains incompletely understood and underused.ObjectiveTo review the epidemiology, pathophysiology, and medical and invasive
treatment of atherosclerosis in patients with diabetes mellitus.Data SourcesUsing the index terms diabetes mellitus, myocardial infarction, peripheral vascular
diseases, cerebrovascular accident, endothelium, vascular smooth muscle, platelets, thrombosis, cholesterol, hypertension, hyperglycemia, insulin, angioplasty, and coronary artery bypass, we
searched the MEDLINE and EMBASE databases from 1976 to 2001. Additional data
sources included bibliographies of identified articles and preliminary data
presented at recent cardiology conferences.Study SelectionWe selected original investigations and reviews of the epidemiology,
pathophysiology, and therapy of atherosclerosis in diabetes. We selected randomized,
double-blind, controlled studies, when available, to support therapeutic recommendations.
Criteria for data inclusion (168 of 396) included publication in a peer-reviewed
journal or presentation at a national cardiovascular society–sponsored
meeting.Data ExtractionData quality was determined by publication in peer-reviewed literature.
Data extraction was performed by one of the authors.Data SynthesisDiabetes mellitus markedly increases the risk of myocardial infarction,
stroke, amputation, and death. The metabolic abnormalities caused by diabetes
induce vascular dysfunction that predisposes this patient population to atherosclerosis.
Blood pressure control, lipid-lowering therapy, angiotensin-converting enzyme
inhibition, and antiplatelet drugs significantly reduce the risk of cardiovascular
events. Although diabetic patients undergo revascularization procedures because
of acute coronary syndromes or critical limb ischemia, the outcomes are less
favorable than in nondiabetic cohorts.ConclusionsSince most patients with diabetes die from complications of atherosclerosis,
they should receive intensive preventive interventions proven to reduce their
cardiovascular risk.

Diabetes and atherosclerosis: epidemiology, pathophysiology, and management.

New drugs for diabetes.

The blood triacylglycerol level is one of the main determinants of blood Mg2+ concentration in individuals with type 2 diabetes. Hypomagnesaemia (blood Mg2+ concentration 27 kg/m2) who participated in the 300-Obesity study (an observational cross-sectional cohort study, as part of the Human Functional Genetics Projects), we investigated the association between serum Mg2+ with laboratory variables, including an extensive lipid profile. In a separate set of studies, hyperlipidaemia was induced in mice and in healthy humans via an oral lipid load, and blood Mg2+, triacylglycerol and NEFA concentrations were measured using colourimetric assays. In vitro, NEFAs harvested from albumin were added in increasing concentrations to several Mg2+-containing solutions to study the direct interaction between Mg2+ and NEFAs. In the cohort of overweight individuals, serum Mg2+ levels were inversely correlated with triacylglycerols incorporated in large VLDL particles (r = −0.159, p ≤ 0.01). After lipid loading, we observed a postprandial increase in plasma triacylglycerol and NEFA levels and a reciprocal reduction in blood Mg2+ concentration both in mice (Δ plasma Mg2+ −0.31 mmol/l at 4 h post oral gavage) and in healthy humans (Δ plasma Mg2+ −0.07 mmol/l at 6 h post lipid intake). Further, in vitro experiments revealed that the decrease in plasma Mg2+ may be explained by direct binding of Mg2+ to NEFAs. Moreover, Mg2+ was found to bind to albumin in a NEFA-dependent manner, evidenced by the fact that Mg2+ did not bind to fatty-acid-free albumin. The NEFA-dependent reduction in the free Mg2+ concentration was not affected by the presence of physiological concentrations of other cations. This study shows that elevated NEFA and triacylglycerol levels directly reduce blood Mg2+ levels, in part explaining the high prevalence of hypomagnesaemia in metabolic disorders. We show that blood NEFA level affects the free Mg2+ concentration, and therefore, our data challenge how the fractional excretion of Mg2+ is calculated and interpreted in the clinic.

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Increased NEFA levels reduce blood Mg2+ in hypertriacylglycerolaemic states via direct binding of NEFA to Mg2.

Several lines of evidence indicate a significant association between insulin and cardiovascular disease. This association might be explained by direct (cardio) vascular effects of insulin. Two hemodynamic actions of insulin are discussed in this review; it induces direct vasodilation in skeletal muscle and stimulation of the sympathetic nervous system. These closely linked effects normally offset each other. Although more insight has been obtained into responses in insulin-resistant individuals and possible mechanisms, direct evidence to support a causative role for insulin is not yet available.

Haemodynamic actions of insulin

Context It has been suggested that stimulation of lipolysis by diazoxide (DZX)-mediated insulin suppression may be useful in treating obesity. However, the optimal dose to promote lipolysis without causing hyperglycemia is unknown. Objective To assess the effects of DZX in nondiabetic obese men on lipid and glucose metabolism. Design Double-blind, placebo (PL)-controlled, 6-month trial in men with a body mass index of 30 to 37.5 kg/m2 treated with a combination of caloric restriction, a standardized exercise program, and DZX or PL dose escalation. Results The mean maximal tolerated dose of DZX was 422 ± 44 mg/d (range, 200 to 700 mg/d). Dose-limiting events were edema (n = 11), hyperglycemia (n = 6), and nausea (n = 2). After dose reduction to a level free of clinical side effects, DZX treatment was associated with a markedly greater decrease in fasting insulin levels than PL (-72.3 ± 3.5% vs -23.0 ± 12.6%; P < 0.001) and a significant improvement of blood pressure and plasma lipid levels. The decline in insulin levels occurred at the cost of a small increase in plasma glucose (0.6 ± 0.2 mmol/L vs -0.1 ± 0.1 mmol/L; P = 0.04) and hemoglobin A1C (0.2 ± 0.1% vs 0.0 ± 0.1%; P = 0.17). Conclusion In nondiabetic obese men, insulin levels can be reduced up to 70% without major metabolic side effects. The marked intersubject variation in maximal tolerated dose indicates that DZX dose titration needs to be individualized.

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Effects of Diazoxide-Mediated Insulin Suppression on Glucose and Lipid Metabolism in Nondiabetic Obese Men.

BACKGROUND: By stimulating sympathetic afferents, repetitive myocardial ischemia induces a state of increased sympathetic tone. HYPOTHESIS: Removing the ischemic trigger by revascularization using percutaneous coronary intervention (PCI) might thus reduce central sympathetic activity in symptomatically stable angina patients. METHODS: A total of 20 patients with stable angina > or = New York Heart Association (NYHA) class II with persistent symptoms despite maximal pharmacological therapy and a clinical indication for PCI, were included in our study. Sympathetic nervous system activity was measured before and 1 month after PCI by a combination of techniques: direct muscle sympathetic nerve activity (MSNA), neurochemical (plasma catecholamine levels), and heart rate variability (HRV). RESULTS: All patients completed the study. After PCI there was a significant reduction in MSNA (pre-PCI 72 +/- 4 to post-PCI 53 +/- 4 burst/100 beats, P < .05) and low frequency/high frequency (LF/HF) ratio (3.7 +/- 0.6 vs 2.4 +/- 0.4, P < .05) consistent with a decline in sympathetic activity. Plasma norepinephrine levels were reduced after PCI, but this difference did not reach statistical significance (1.84 +/- 0.17 vs 1.73 +/- 0.13 nmol/L, P = not significant). CONCLUSION: Coronary revascularization by PCI reduces sympathetic activity in patients with established myocardial ischemia.

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Cees J. Tack

Papers

New drugs for diabetes.

Increased NEFA levels reduce blood Mg2+ in hypertriacylglycerolaemic states via direct binding of NEFA to Mg2.

Haemodynamic actions of insulin

Effects of Diazoxide-Mediated Insulin Suppression on Glucose and Lipid Metabolism in Nondiabetic Obese Men.

Improving myocardial perfusion by percutaneous coronary intervention reduces central sympathetic activity in stable angina.