Deficiency of the insulin, glucose-mediated decrease in serum triglycerides in normolipidemic obese subjects.

The effects of a 6-h insulin, glucose infusion on lipid metabolism were compared in 29 normolipidemic obese and 20 control subjects. Alterations in serum triglycerides (TG), cholesterol, and high-density lipoprotein (HDL) cholesterol were similar within groups when either 40 or 120 mU/m2 per min of regular insulin were infused. Although changes in the HDL cholesterol responses to the insulin, glucose infusions were also similar in obese and control subjects, TG fell more in insulin, glucose-infused controls (35 +/- 4 mg/dl, means +/- s.e.m.) than obese subjects (23 +/- 3) (P less than 0.001). The rate and magnitude of the insulin, glucose-mediated fall in free fatty acids, however, were not different between the two groups. This diminished responsiveness of TG to an insulin, glucose infusion in normotriglyceridemic obese subjects is another manifestation of the insulin resistance of obesity.