Acarbose (Bay g 5421, Glucobay; CAS 56180-94-0) inhibits alpha-glucosidases of the small intestine and thus delays glucose release from complex carbohydrates. It is therefore efficient as a first-line drug in the treatment of noninsulin-dependent diabetics (NIDDM) insufficiently treated with diet alone. Information is scarce whether under acarbose treatment the lipid metabolism can also be improved. Therefore the changes of triglycerides, cholesterol and HDL-cholesterol were analyzed in a randomized double-blind placebo-controlled trial. In brief, 94 NIDDM aged 43 to 70, after a pretreatment period of at least 3 months, were treated with 100 mg acarbose t.i.d. or placebo for 24 weeks. The patients were recruited after a 4-week screening phase with reinforcement of diet. The most impressive results of acarbose treatment were lowering of blood glucose and insulin, especially in the postprandial state, and of HbA1 (glycosylated hemoglobin). Results on lipids: The initial serum cholesterol levels showed a broad spectrum. Low concentrations remained unchanged under acarbose, while high concentrations (the upper tercile) decreased from 273 to 251 mg/dl. This effect was statistically significant compared to placebo. HDL-cholesterol levels increased continuously under acarbose and placebo as well thus indicating some study effect. Similarly, fasting triglycerides leveled down under acarbose and placebo. However, drastic differences appeared in postprandial triglycerides which were checked 1 and 5 h after a test meal given at entry and at finish of the study. The lowering by acarbose compared to placebo was highly significant for the 1 h postprandial concentrations. It is concluded that acarbose treatment can reduce elevated cholesterol concentrations and postprandial triglyceride concentrations.(ABSTRACT TRUNCATED AT 250 WORDS)