Goldberg Rb

PATHOGENESIS OF NONKETOTIC HYPEROSMOLAR DIABETIC COMA

Two concepts are advanced to explain some fo the puzzling biochemical features found in nonketotic hyperosmolar diabetic coma. It is firstly suggested that an insulinised liver (reflecting residual beta-cell secretory activity) coexists with a diabetic periphery, thereby inactivating intrahepatic oxidation of incoming free fatty acids, which are directed largly along nonketogenic metabolic pathways such as triglyceride synthesis. This could account for the lack of hyperketonaemia. Secondly, it is hypothesised that within the liver enhanced neoglucogenesis occurs, due to the prevailing portal-vein into ratio of glucagon to insulin, and is mainly responsible for the development of massive hyperglycaemia.

Adipose cell size in obese Africans: evidence against the existence of insulin resistance in some patients

Aspects of adipose tissue cellularity were examined in 15 non-diabetic premenopausal African women with simple obesity living in Johannesburg. A smaller group of six non-obese Black women served as controls. Adipose tissue was obtained by biopsy from the deltoid, gluteal, and abdominal regions, and the mean fat cell size for each site was determined. Fasting plasma glucose, insulin, and lipid levels, and the glucose and insulin responses to a 100 g oral glucose load, in these subjects provided metabolic data for correlative analyses. As expected, the overall mean and regional adipocyte sizes were significantly larger in the overweight subjects. Significant regional variations in fat cell size were also seen, the gluteal region adipocytes being larger than those of other sites in both obese and non-obese women. A significant positive correlation was found between fat cell size and the percentage of ideal body weight. There was no significant relationship between adipocyte size, however, and any of the metabolic variables measured--notably basal or stimulated plasma insulin. Nearly half of the overweight women showed large adipocytes with normal plasma insulin concentrations. A proportion of African women with hypertrophic obesity do not appear to demonstrate any classical metabolic features of insulin resistance; this may be related partly to their high carbohydrate intake and unusual degree of physical activity. Our results do not, however, indicate that hyperinsulinaemia is completely absent in obese Black women.

Some metabolic relationships in young patients with ischemic heart disease

The interrelationships between body weight, insulin secretion and serum lipids were studied in 40 young white patients (mean age 37 years) with established ischemic heart disease (IHD), living in Johannesburg. None was severely obese, hypertensive or overtly diabetic. In general, strong positive correlations were found between body weight and insulin concentrations and between insulin levels and fasting serum triglycerides. However, insulin levels were relatively low in 4 patients with marked hypertriglyceridemia (above 350 mg/dl). These data are consistent with the postulate that insulin promotes (hepatic) triglyceride synthesis, but when there is gross hypertriglyceridemia peripheral triglyceride clearance becomes defective. Insignificant correlations were observed between body weight and serum lipids and between cholesterol and other metabolic variables. We conclude that there is a sequential link between increasing body weight, insulin secretion and triglyceride levels in young patients with IHD, but that cholesterolemia is independent of this axis.