Influence of obesity, impaired glucose tolerance, and NIDDM on LDL structure and composition. Possible link between hyperinsulinemia and atherosclerosis

The possible causes of the enhanced risk for coronary heart disease (CHD) were examined in morbidly obese women with normoglycemia, impaired glucose tolerance (IGT), and non-insulin-dependent diabetes mellitus (NIDDM) before and after gastric bypass surgery. Compared with age-matched lean women, plasma lipid and apolipoprotein concentrations of the obese women before surgery favored atherogenesis. The risk for CHD may further be exacerbated in the IGT and NIDDM groups by the prevalence of smaller and denser low-density-lipoprotein (LDL) particles. LDL size correlated negatively with plasma insulin levels independent of triglyceride levels, age, or body mass index (BMI). After surgery, BMI, plasma insulin, and triglyceride levels decreased, but LDL size increased, and LDL density decreased. Neither cholesterol nor LDL cholesterol levels were affected after surgery, but high-density-lipoprotein cholesterol was increased in all patients after surgery. Although the mechanisms underlying the changes in the properties of LDL could not be determined from this study, these changes appear to be of benefit in reducing CHD risk in these patients.

Hyperinsulinaemia and other metabolic disturbances in well-controlled hypertensive men and women: an epidemiological study of the Dalby population

Hypertensive subjects who have received no treatment have been found to be hyperinsulinaemic in previous studies using different populations. The present study was carried out to further examine the metabolic disturbances in carefully treated hypertensive subjects [diastolic blood pressure (DBP) less than 90 mmHg] of both sexes from the Dalby population. Three hundred and ten subjects who had been hypertensive for more than 5 years [DBP 88.1 +/- 0.5 (mean +/- s.e.m.)] were compared with 288 normotensive controls, matched for sex and age and chosen from the same population. After an overnight fast and with no medication for 24 h, an oral glucose tolerance test was carried out. P-insulin and P-C-peptide were analysed and insulin sum (P-insulin at start + after 2 h of oral glucose tolerance test) and C-peptide sum were calculated. Insulin and C-peptide sums were higher (P less than 0.001) in the hypertensive than in the normotensive subjects; 0.69 +/- 0.03, 3.36 +/- 0.08 and 0.41 +/- 0.02, 2.74 +/- 0.06, respectively. The diagnosis of hypertension, not the attained blood pressure level, correlated with insulin and C-peptide sums in multivariate analyses; F-values 20.96 (n = 598; P less than 0.001) and 6.68 (P less than 0.01), respectively. Hypertensive subjects under treatment, using calcium antagonists as monotherapy (n = 21), did not differ in age or body mass index from other hypertensives, but they had lower values for insulin and C-peptide sums; 0.45 +/- 0.05 and 2.63 +/- 0.18. Angiotensin converting enzyme inhibitors were not frequently used for monotherapy.(ABSTRACT TRUNCATED AT 250 WORDS)

Diabetes, hyperinsulinemia, and hyperlipidemia in small aboriginal community in northern Australia

A small rural Aboriginal community in northern Australia was surveyed for diabetes, impaired glucose tolerance (IGT), hyperinsulinemia, and lipid levels. Of the 122 adults greater than 17 yr of age who participated (95% response rate), 11.5% had diabetes, 7.4% had IGT, and the remaining 81.1% had normal glucose tolerance. Both diabetes and IGT were strongly age related. This high frequency of diabetes occurred, despite the population being relatively lean. Although the body mass index (BMI) increased with age in both men and women, only 25% of the population overall had BMI greater than 25 kg/m2. There were wide ranges of insulin responses to glucose, with the upper tertile of 2-h insulin levels being more than seven times higher than the lower tertile (144 +/- 13 vs. 19 +/- 1 mU/L). Hyperinsulinemia was associated with IGT, elevated triglycerides, and lower high-density lipoprotein cholesterol levels. Lipid abnormalities were much more frequent among men than women. Cholesterol levels were an average of 0.55 mM higher and triglycerides an average of 1.05 mM higher in men than in women, and both increased with age. In conclusion, this small isolated Aboriginal population from northern Australia had an unexpectedly high frequency of diabetes (in view of their relative leanness) in association with a high frequency of metabolic abnormalities indicative of insulin resistance (hyperinsulinemia, IGT, hypertriglyceridemia).

An inconsistent relationship between insulin and blood pressure in three Pacific island populations

The evidence linking insulin to blood pressure is controversial, and results for groups similarly categorized by body mass, glucose tolerance and hypertensive status are often contradictory. We have investigated the relationship in three population-based samples of Micronesian (Nauru), Polynesian (Western Samoa) and Melanesian (New Caledonia) Pacific islanders, who are known to be susceptible to obesity, non-insulin-dependent diabetes mellitus (NIDDM), hyperinsulinaemia and hypertension. After controlling for age and body mass index (BMI), mean fasting and 2-hr (post 75 g glucose) insulin levels were not significantly different between hypertensive and non-hypertensive subjects, in any population or glucose tolerance sub-group, excepting 2-hr insulin in New Caledonians with normal glucose tolerance. Similarly, there were no strong trends for a higher prevalence of hypertension amongst those with insulin levels in the upper quartile of the distribution of each population, although it was apparent in some BMI/glucose tolerance sub-groups of two populations. Multiple linear regression analyses also showed an inconsistent and where present, weak, independent association between insulin and blood pressure in models predicting both systolic and diastolic blood pressure. We therefore conclude that the hypothesis implicating insulin as a major determinant of blood pressure and as the pathophysiological link between obesity, NIDDM and hypertension is not strongly supported either by the literature or the present data.

Persistent neonatal hyperinsulinism

Over a 3-year period, the diagnosis of persistent neonatal hyperinsulinism (PNH) was made in seven infants, from an unselected cohort of 18,726 births, all of Saudi Arabian origin. Thus the incidence of PNH was one in 2,675 births. The high incidence, associated consanguinity, and occurrence in siblings suggest that PNH may be inherited as an autosomal recessive disorder.

Comparison of body composition, adipocyte size, and glucose and insulin concentrations in Pima Indian and Caucasian children

Pima Indian adults with normal glucose tolerance have higher plasma glucose and insulin concentrations than Caucasian adults. To estimate the age of onset of these differences, and to assess their relationship to abdominal and gluteal adipocyte size, we measured adiposity, adipocyte size, and glucose and insulin concentrations during a glucose tolerance test in lean (less than 20% body fat), prepubertal children from each race. The Pima (n = 13) and Caucasian (n = 10) groups were of similar age, percent body fat, and weight. Pima Indian children had higher fasting glucose (101 +/- 2 v 94 +/- 2 mg/dL, P = .01) and insulin (22 +/- 2 v 15 +/- 2 microU/mL, P less than .01) concentrations and larger abdominal adipocytes (0.49 +/- 0.03 v 0.37 +/- 0.04 microgram lipid/cell, P less than .05) than the Caucasian children. Postprandial glucose and insulin concentrations and gluteal adipocyte size were similar in the two races. The higher plasma glucose and insulin concentrations found in Pima adults are present in lean Pima children, and are associated with increased abdominal adipocyte size. These increases may precede the development of obesity in this racial group.

The newborn of diabetic mothers. Observations on 154 cases, 1958-1972

The authors report their observations on 154 newborns of diabetic mothers from 1958 to 1973. The total neonatal mortality is 14.28%. In fact, in a first period from 1958 to January 1971 the mortality was 19.23% and from January 1971 to January 1973 it was only 4%. The improvement was caused by the prolongation of the pregnancy (average duration 36 weeks in the first period, 37 in the second), decreasing the number of hyaline membranes. The authors study the dangers confronting this newborn; they stress the importance of hypoglycaemia observed in 89 cases. They prove that this hypoglycaemia is in correlation with an hyperinsulinism of the newborn, observed even taking into account the presence of anti-insulin antibodies checked in the patients. The authors also study the future of these infants: 97 infants of more than 2 years of age have been reviewed on one or more occasions; only one of them became diabetic.