Effects of biosynthetic human proinsulin on plasma lipids in type 2 diabetes mellitus.

Plasma cholesterol, triglycerides, HDL2-cholesterol, and HDL3-cholesterol were studied in 18 patients with Type 2 diabetes. Prior to entering the clinical trial, the study subjects were in stable control under a fixed mixture of 20% regular and 80% NPH (isophane) biosynthetic human insulin twice daily. The patients were randomized to treatment with either biosynthetic human proinsulin or biosynthetic human NPH insulin (controls) twice daily. Glucose control was kept constant in both groups throughout the study. Of the nine patients treated with proinsulin, eight exhibited a decrease of plasma triglycerides (median decrease by 0.13 mmol/l). In contrast, all nine controls showed a rise (median increase by 0.69 mmol/l) of plasma triglycerides (p<0.001). In keeping with the fall of plasma triglycerides, HDL2-cholesterol rose in all but one proinsulin-treated patients. Both treatment modalities reduced HDL3-cholesterol with a median decrease of 0.20 mmol/l (p<0.01) with proinsulin and 0.26 mmol/l with NPH insulin (p<0.05).