Metabolic effects of pioglitazone and rosiglitazone in patients with diabetes and metabolic syndrome treated with glimepiride: a twelve-month, multicenter, double-blind, randomized, controlled, parallel-group trial

Abstract

Background: Glimepiride is approved as monotherapy and in combination with metformin or with insulin, whereas the combination of glimepiride with other antihyperglycemic drugs is under investigation.

Objective: The aim of this study was to assess the differential effect on glucose and lipid variables and tolerability of the combination of glimepiride plus pioglitazone or rosiglitazone in patients with type 2 diabetes mellitus (DM) and metabolic syndrome.

Methods: This 12-month, multicenter, double-blind, randomized, controlled, parallel-group trial was conducted at 3 study sites in Italy. We assessed patients with type 2 DM (duration, > or =6 months) and with metabolic syndrome. All patients were required to have poor glycemic control with, or to have experienced > or =1 adverse effect (AE) with, diet and oral hypoglycemic agents such as sulfonylureas or metformin, both given up to the maximum tolerated dose. All patients received a fixed oral dose of glimepiride, 4 mg/d divided into 2 doses, self-administered for 12 months. Patients also were randomized to receive oral pioglitazone (15 mg once daily) (G + P group) or oral rosiglitazone (4 mg once daily) (G + R group), self-administered for 12 months. We assessed body mass index (BMI), glycemic control (glycosylated hemoglobin [HbA(1c)], fasting and postprandial plasma glucose and insulin levels [FPG, PPG, FPI, and PPI, respectively], and homeostasis model assessment index), lipid profile (total cholesterol [TC], low-density lipoprotein cholesterol [LDL-C], high-density lipoprotein cholesterol [HDL-C], and triglycerides [TG]), and lipoprotein variables (apolipoprotein [apo] A-I and apo B) at baseline and at 3, 6, 9, and 12 months of treatment. Treatment tolerability was assessed at each study visit using a thorough interview of patients, and comparisons of clinical and laboratory values to baseline levels.

Results: A total of 91 patients were enrolled in the study; 87 patients completed it (G + P group: 24 women, 21 men; mean [SD] age, 53 [6] years; G + R group: 20 women, 22 men; mean [SD] age, 54 [5] years). Patients in the G + P and G + R groups experienced significant increases in mean BMI at 12 months compared with baseline (4.92% and 6.17%, respectively; both, P < 0.05). The combination of glimepiride with pioglitazone or rosiglitazone significantly improved glycemic control in the study patients. At 12 months, we observed a 1.3% improvement in mean values for plasma HbA(1c) concentration (P < 0.01) 19.3% in FPG (P < 0.01), 16.3% in PPG (P < 0.01), 42.4% in FPI ), and 23.3% in PPI (P <0.05); no significant differences were found between treatment groups. Although the G + P group experienced a significant improvement at 12 months in almost all variables of lipid metabolism from baseline (TC, - 11%; LDL-C, -12%; HDL-C, 15%; and apo B, - 10.6% [all, P , 0.05]), the G + R group experienced a significant increase in mostly the lipid risk factors for cardiovascular disease (TC, 14.9%; LDL-C, 16.5%; TG, 17.9%; and apo B, 10.3% [all, P , 0.05]). Overall, no statistically significant changes in plasma aminotransferase activities were observed. Of the 87 patients who completed the study, 6.7% (3/45) of patients in the G + P group and 11.9% (5/42) of patients in the G + R group had transient, mild to moderate AEs that did not cause withdrawal from the trial.

Conclusion: In this study of patients with type 2 DM and metabolic syndrome who did not respond adequately to, or experienced AEs with, diet and either a sulfonylurea or metformin previously, the combination of glimepiride plus pioglitazone was associated with a significant improvement in lipid and lipoprotein variables, whereas the combination of glimepiride plus rosiglitazone appears to not have had any clinically significant effect on lipid metabolism.