Bezafibrate improves insulin resistance evaluated using the glucose clamp technique in patients with type 2 diabetes mellitus: a small-scale clinical study

BACKGROUND: Bezafibrate is mainly used to treat hypertriglyceridemia. Studies have reported that bezafibrate also improves type 2 diabetes mellitus, but the mechanism has not been fully elucidated. We performed euglycemic hyperinsulinemic clamps (glucose clamp) and meal tolerance tests (MTT) to examine the effects of bezafibrate on insulin resistance in patients with type 2 diabetes mellitus. METHODS: Twelve Japanese patients with type 2 diabetes mellitus and dyslipidemia (mean age: 59.5 years; fasting plasma glucose: 7.95 mmol/L; hemoglobin A1c [HbA1c]: 7.3%; body mass index: 26.5 kg/m(2)) underwent a glucose clamp and MTT before and after 12 weeks of treatment with 400 mg/day bezafibrate. The glucose infusion rate was measured during the glucose clamp. The patients took a test meal (460 kcal) in the MTT. Plasma glucose and immunoreactive insulin levels were measured at 0 (fasting), 30, 60, 120, and 180 min. Serum C-peptide immunoreactivity, serum lipids, and liver function markers were also measured during the MTT. RESULTS: Bezafibrate significantly increased the mean glucose infusion rate from 5.78 ± 1.94 to 6.78 ± 2.52 mg/kg/min (p < 0.05). HbA1c improved from 7.30 ± 0.55% to 7.02 ± 0.52% (p < 0.05). In the MTT, fasting plasma glucose decreased from 7.95 ± 1.15 to 6.98 ± 1.07 mmol/L (p < 0.05). The area under the plasma glucose curve from 0 to 180 min decreased significantly from 29.48 ± 5.07 to 27.12 ± 3.98 mmol/h/L (p < 0.05), whereas immunoreactive insulin was unchanged. Furthermore, bezafibrate also significantly improved serum lipids, with decreases in triglyceride levels from 1.84 ± 0.88 to 1.14 ± 0.41 mmol/L (p < 0.05), low-density lipoprotein cholesterol levels from 3.56 ± 0.83 to 2.92 ± 0.55 mmol/L (p < 0.05), and remnant-like particle cholesterol levels decreased from 0.25 ± 0.16 to 0.14 ± 0.06 mmol/L (p < 0.05), and increases in high-density lipoprotein cholesterol levels from 1.50 ± 0.24 to 1.66 ± 0.29 mmol/L (p < 0.05). CONCLUSIONS: Bezafibrate improved glucose intolerance and peripheral insulin resistance in these Japanese patients with type 2 diabetes mellitus and dyslipidemia. Therefore, bezafibrate could be used to treat insulin resistance in patients with type 2 diabetes mellitus and dyslipidemia. TRIAL REGISTRATION: University Hospital Medical Information Network (UMIN) Clinical Trials Registry, UMIN000012462.