[Mechanisms of hypoglycemic action of benfluorex]

Benfluorex is a hypolipidemic agent with biguanide-like properties. Its action on glucose metabolism was evaluated in 6 NIDDM patients previously treated with diet alone. Before and after 1 month of benfluorex therapy (450 mg/day p.o.), an euglycemic (100 mg/dl) insulin (40 mU/m2/min) clamp was performed along with 3-3H-glucose infusion and indirect calorimetry. Benfluorex did not affect body weight, while it reduced fasting plasma glucose (144 +/- 16 vs 119 +/- 8 mg/dl; P < 0.05), glycosylated hemoglobin (6.8 +/- 0.8 vs 6.4 +/- 0.4 percent) and fructosamine (2.9 +/- 0.6 vs 2.4 +/- 0.2 mmol/l; P < 0.05). Both triglycerides (2.3 +/- 0.6 vs 1.9 +/- 0.5 mmol/l) and total cholesterol (5.7 +/- 0.7 vs 5.2 +/- 0.6 mmol/l) declined. No changes occurred in plasma fatty acid, insulin, and C-peptide. Basal hepatic glucose production did not change and it was completely suppressed during the clamp studies both before and after benfluorex. Basal oxidation rates of carbohydrates and lipids did not change significantly. During the insulin clamp study, insulin-mediated glucose disposal increased after benfluorex (5.7 +/- 0.3 vs 4.8 +/- 0.2 mg/kg/min; P < 0.01). Lipid oxidation was equally suppressed before and after therapy with benfluorex. Glucose oxidation was not enhanced after benfluorex while non-oxidative glucose metabolism was significantly improved (2.2 +/- 0.7 vs 3.4 +/- 0.4 mg/kg/min; P < 0.05).

short-term benfluorex administration a) improves glucose and lipid control, b) improves insulin action by enhancing non-oxidative glucose metabolism, c) does not affect basal insulin secretion. The long-term effect of benfluorex treatment remains to be evaluated.