The effects of administration of an alpha-glucosidase inhibitor and a sulphonylurea compound on lipid profile were investigated in patients with non-insulin-dependent diabetes mellitus, (NIDDM) previously treated with sulphonylurea compounds alone, but in whom metabolic control was inadequate. A group of patients (n = 10) were treated with the alpha-glucosidase inhibitor at a dose of 0.2 mg, three times daily, for 4 weeks. Treatment significantly reduced the post-prandial glucose level and the serum total cholesterol level. In addition, there were non-significant reductions in the triglyceride and very low density lipoprotein levels. These preliminary results suggest that administration of alpha-glucosidase inhibitors might improve the lipid profile of patients with NIDDM.