Objective To determine whether reducing triglyceride concentrations in humans reduces serum insulin levels and consider the implications of this for the insulin resistance of hypertriglyceridemia.

Research Design and Methods Insulin and glucose levels were determined during an oral glucose tolerance test (OGTT) in 14 volunteers who had a range of basal triglyceride levels. A double-blind crossover design was used to study active and placebo gemfibrozil and relate triglyceride changes to insulin and glucose levels. Diet and weight were kept constant.

Results Glucose concentrations during OGTT were the same in both treatment periods. Insulin concentrations were reduced in proportion to reductions in triglyceride.

Conclusions Triglyceride reduction in hypertriglyceridemic patients is associated with a decrease in serum insulin. This does not appear to be a direct effect of gemfibrozil, because it does not occur without a sufficient fall in triglyceride levels. Because glucose concentration remains the same despite the reduced insulin, the triglyceride reduction may result in greater sensitivity to insulin. Treatment of hypertriglyceridemia may break a vicious and potentially atherogenic cycle of hypertriglyceridemia and hyperinsulinemia.