The effects of oral hypoglycaemic drugs on serum lipids and lipoproteins in non-insulin-dependent diabetes (NIDDM)

Abstract

Coronary heart disease is a major cause of morbidity in NIDDM and is likely to be related to the abnormalities in serum lipids and lipoproteins commonly associated with it. The effects of treatment in general, and of oral hypoglycaemic drugs in particular, on serum lipids in NIDDM are not clear. In a cross-over study, the effects of 3 months treatment with metformin glibenclamide on body weight, blood glucose control, and serum lipoproteins were compared in 35 patients with NIDDM, inadequately controlled by diet alone. Glibenclamide alone increased body weight. Glibenclamide and metformin achieved equivalent blood glucose control, independent of initial body mass index. Neither drug affected serum triglyceride. Metformin significantly reduced low density lipoprotein cholesterol (mean change -0.34 mmol/1.95% confidence intervals -0.12 to -0.57 mmol/l, p less than 0.01). Neither drug altered high density lipoprotein or subfraction cholesterol. Changes in serum lipoproteins were also studied in 14 patients with NIDDM on long term metformin therapy, after 6 weeks placebo and again 6 weeks after restarting active drug therapy. Withdrawal of metformin resulted in a rise in fasting blood glucose, HbA1, serum total and low density lipoprotein (LDL) cholesterol. Restarting the drug reversed these changes. Multivariate analysis showed that serum total and LDL cholesterol varied with treatment, but not with glycaemic control. Metformin can therefore lower total and LDL cholesterol in NIDDM and this effect appears to be maintained long term.