Showing papers by "Barbara V. Howard published in 1991"
TL;DR: The relations between insulinemia, insulin resistance, and blood pressure differ among racial groups and may be mediated by mechanisms active in whites, but not in Pima Indians or blacks.
Abstract: Background. Insulin resistance and the concomitant compensatory hyperinsulinemia have been implicated in the pathogenesis of hypertension. However, reports on the relation between insulin and blood pressure are inconsistent. This study was designed to investigate the possibility of racial differences in this relation. Methods. We studied 116 Pima Indians, 53 whites, and 42 blacks who were normotensive and did not have diabetes; the groups were comparable with respect to mean age (29, 30, and 31 years, respectively) and blood pressure (113/70, 111/68, and 113/68 mm Hg, respectively). Insulin resistance was determined by the euglycemic—hyperinsulinemic clamp technique during low-dose (40 mU per square meter of body-surface area per minute) and high-dose (400 mU per square meter per minute) insulin infusions. Results. The Pima Indians had higher fasting plasma insulin concentrations than the whites or blacks (176, 138, and 122 pmol per liter, respectively; P = 0.002) and lower rates of whole-body gl...
433 citations
TL;DR: Compared with children studied early in this century, present-day Pima children are much heavier for height, suggesting that the degree of obesity has increased since that time.
326 citations
TL;DR: In individuals having a wide range of obesity and glucose tolerance, substitution of complex carbohydrates for saturated fat has beneficial effects of lowering LDL cholesterol and possibly improving glucose tolerance and insulin secretion but without having any adverse effects on lipoprotein metabolism or energy expenditure.
Abstract: Dietary recommendations for diabetic patients now generally include the reduction of total and saturated fat and an increase in complex carbohydrates. We conducted two series of studies on individuals with obesity and/or non-insulin-dependent diabetes mellitus (NIDDM) to assess the effects of this dietary recommendation on both lipoproteins and their metabolism as well as on insulin secretion and action and energy expenditure. Both series compared a diet high in saturated fat with a diet high in complex carbohydrates and fiber. Calories and proportion of protein were constant. In the first set of studies, we sought to examine the effect of replacement of saturated fat with complex carbohydrate in a regimen with conventional foods that would closely approximate foods expected to be used and recommended to diabetic patients. In the second regimen, we examined a more extreme difference between carbohydrate content and fat content using a dietary change that would approximate the contrasts between traditional diets of Native Americans or other cultures and a modern westernized diet. The effects on lipoproteins included consistent decreases in total and low-density lipoprotein (LDL) cholesterol (av 10%), minimum to no change in high-density lipoprotein cholesterol, and insignificant changes in total or very-low-density lipoprotein (VLDL) triglycerides or 24-h triglyceride profiles. Changes in total and LDL cholesterol required 3-4 wk to reach equilibrium. Metabolic studies used to elucidate the reasons for the decrease in LDL cholesterol confirmed no stimulation of VLDL triglyceride or apolipoprotein B (apoB) production on the high-carbohydrate diet. The decrease in LDL appeared to be due to decreases in mechanisms that convert VLDL to LDL and increased activity of LDL apoB clearance. There were no changes in fasting and 2- or 24-h glucose profiles or in fasting and 2-h insulin concentrations in individuals consuming a diet of 30% fat and 55% carbohydrate. However, in the study with traditional foods, where dietary carbohydrate was 70% and fat only 15%, there was an improvement in glucose tolerance. It was accompanied by an improvement in glucose-mediated glucose disposal and insulin secretion. Finally, with a whole-body calorimeter, we found no difference between the high-fat and high-carbohydrate diets in terms of 24-h energy expenditure. In individuals having a wide range of obesity and glucose tolerance, substitution of complex carbohydrates for saturated fat has beneficial effects of lowering LDL cholesterol and possibly improving glucose tolerance and insulin secretion but without having any adverse effects on lipoprotein metabolism or energy expenditure.
48 citations
TL;DR: A lower metabolic rate was a determinant of future weight gain, and abnormalities in use of free fatty acids and cell insulin action were suggested, which emphasize the need for further studies in these areas.
44 citations
TL;DR: The middle-aged obese rhesus monkey is an animal model in which these defects can be separated in time during the development of diabetes, and can be used to study lipoprotein abnormalities as they occur both before and in noninsulin-dependent diabetes.
Abstract: Abnormalities in plasma lipoprotein concentrations commonly found in subjects with noninsulin-dependent diabetes may be related to insulin resistance, hyperinsulinemia, hyperglycemia, or other metabolic defects. The middle-aged obese rhesus monkey is an animal model in which these defects can be separated in time during the development of diabetes. It is, therefore, a model system for examining the sequence of metabolic changes which occur before and after the onset of diabetes. This sequence of changes was used in the present study to determine if lipoprotein changes occur in association with the development of diabetes in the rhesus monkey. Increases in plasma triglyceride, very low density lipoprotein (VLDL) triglyceride, and VLDL cholesterol, and decreases in high density lipoprotein cholesterol were observed across previously identified groups ranging from normal to diabetic. Plasma triglycerides increased from 0.54 ± 0.09 (normal) to 1.27 ± 0.50, 1.93 ± 0.79, and 4.28 ± 2.24 in three intermediate gr...
34 citations
TL;DR: Both micro-and macrovascular complications occur frequently in previously undiagnosed Chinese diabetics and the frequency of CHD is markedly increased compared to the low frequency among Chinese non-diabetics.
Abstract: In 1986, 110,660 of 281,589 residents aged 25-74 years in Da Qing, Hei Long Jiang Province of China, were surveyed. Based on the results of a 75-g oral glucose tolerance test, 630 subjects were found to have previously undiagnosed diabetes according to 1985 WHO criteria. Among them, 600 diabetics aged 35-74 years (288 men, 312 women) and 410 non-diabetics of similar age with normal glucose tolerance (207 men, 203 women) were examined to determine the prevalence of retinopathy and coronary heart disease (CHD) and to evaluate associated characteristics. Retinal examinations of 423 newly diagnosed diabetics showed that 15.4% had several microaneurysms and/or small intraretinal haemorrhage, 5.5% soft exudates, 7.1% hard exudates, and 2.3% proliferative retinopathy. Among 220 non-diabetics, 13.6% had one or two microaneurysms and/or small intraretinal haemorrhage, and only 1.4% had a few soft exudates; half of the non-diabetics with retinopathy had hypertension. CHD, according to Minnesota coding (1.1-1.3, 5.1-5.3 and 7.1) of resting electrocardiograms, was ten times more frequent in the diabetics (3.59%) than in the controls (0.32%), after adjusting for age and sex. Multiple regression analysis showed that plasma glucose concentration was a risk factor for retinopathy after adjusting for age, sex, body mass index (BMI), smoking and blood pressure. Two-hour plasma glucose concentration (after adjusting for age, sex, BMI, smoking and blood pressure) and blood pressure (after adjusting for age, sex BMI, smoking and 1-h or 2-h plasma glucose level) were associated with CHD among the diabetics and non-diabetics and among the diabetics alone. Thus, both micro- and macrovascular complications occur frequently in previously undiagnosed Chinese diabetics and the frequency of CHD is markedly increased compared to the low frequency among Chinese non-diabetics.
33 citations