Effects of bezafibrate on insulin sensitivity and glucose tolerance in subjects with combined hyperlipidemia

To investigate whether the lowering of triglyceride levels has beneficial effects on glucose metabolism, we studied 13 nondiabetic men with combined hyperlipidemia (phenotype IIB) before and after 2 months of treatment with a slow-release formulation of bezafibrate (400 mg daily). The rates of whole body glucose disposal were quantitated by the euglycemic hyperinsulinemic clamp technique (insulin infusion rate of 80 mU/m2/min). In an oral glucose tolerance test, fasting glucose level decreased slightly (5.0 +/- 0.2 versus 4.8 +/- 0.2 mmol/L; p < 0.05) during bezafibrate treatment. Glucose and insulin levels after an oral glucose load remained unchanged. Rates of whole body glucose disposal did not change during bezafibrate treatment (39.5 +/- 3.3 mumol/kg/min before treatment versus 40.6 +/- 2.7 mumol/kg/min after treatment; difference not significant). Basal hepatic glucose output also remained unchanged (8.2 +/- 0.2 mumol/kg/min before treatment versus 8.3 +/- 0.2 mumol/kg/min after treatment; difference not significant). Our findings show that bezafibrate has a triglyceride-lowering effect without any significant influence on insulin sensitivity.