Metabolic Variations with Oral Antidiabetic Drugs in Patients with Type 2 Diabetes: Comparison Between Glimepiride and Metformin

Patients with Type 2 diabetes (T2DM) are at high risk of morbidity and mortality from cardiovascular complications, and hypoglycaemia increases this risk. Furthermore, other metabolic parameters exacerbate cardiovascular risk in these patients. The aim of the study was to compare the metabolic effects of glimepiride and metformin in patients with T2DM. We evaluated 164 patients with T2DM (80 males, 84 females) in a multicentre, randomised, controlled, open, parallel group study comparing glimepiride with metformin. Eighty-one patients (aged 56+/-10 yr) received glimepiride (3+/-1 mg/d); 83 patients (aged 58+/-9 yr) received metformin (2500+/-500 mg/d). Patients had been diagnosed for < or = 6 months; they were non-smokers; had no hypertension or coronary heart disease; were not taking hypolipidaemic drugs, diuretics, beta-blockers or thyroxin; and had normal renal function. Metabolic parameters were measured after 6 and 12 months of treatment. Glimepiride significantly lowered lipoprotein(a) [Lp(a)] and homocysteine levels (HCT) at 6 and 12 months. Both glimepiride and metformin lowered plasminogen activator inhibitor Type 1 (PAI-1) at 12 months and significantly improved levels of glycosylated haemoglobin, fasting plasma glucose and post-prandial plasma glucose after 6 and 12 months. Metformin significantly lowered fasting plasma insulin and postprandial plasma insulin. Glimepiride and metformin also reduced levels of other metabolic parameters in patients with T2DM. In particular, glimepiride significantly reduced HCT, Lp(a), and PAI-1 levels, important metabolic risk factors for atherosclerotic vascular disease. These reductions may be owing to improved glucose metabolism, but it cannot be excluded that these drugs have a direct effect on additional metabolic parameters.