One-Year Glycemic Control With a Sulfonylurea Plus Pioglitazone Versus a Sulfonylurea Plus Metformin in Patients With Type 2 Diabetes

Abstract

OBJECTIVE—The goal was to assess the 1-year efficacy and safety of the addition of pioglitazone or metformin to existing sulfonylurea (SU) therapy in patients with inadequately controlled type 2 diabetes. RESEARCH DESIGN AND METHODS—In this multicenter, double-blind study, patients were randomized to receive either pioglitazone 15 mg (n = 319) or metformin 850 mg (n = 320) and up to 45 mg/day and 2,550 mg/day, respectively. The primary efficacy endpoint was HbA1c at week 52. Fasting plasma glucose, insulin, and lipid profiles were also measured. RESULTS—HbA1c was reduced by 1.20% in the SU plus pioglitazone group and 1.36% in the SU plus metformin group, and fasting plasma glucose was reduced by 2.2 and 2.3 mmol/l in the respective groups. Fasting insulin levels were also reduced (pioglitazone arm −1.3 μIU/ml; metformin arm −0.8 μIU/ml). There were no significant between-treatment differences in these three parameters. Pioglitazone addition to SU significantly reduced triglycerides (−16 vs. −9%; P = 0.008) and increased HDL cholesterol (14 vs. 8%; P < 0.001) compared with metformin addition. LDL cholesterol was increased 2% by the addition of pioglitazone and decreased 5% by the addition of metformin to SU (P < 0.001). Urinary albumin-to-creatinine ratio was reduced by 15% in the SU plus pioglitazone group and increased 2% in the SU plus metformin group (P = 0.017). Both combinations were well tolerated with no evidence of hepatic or cardiac toxicity in either group. CONCLUSIONS—Clinically equivalent improvements in glycemic control were observed for both combinations. Compared with metformin plus SU, addition of pioglitazone to SU resulted in a reduction of the urinary albumin-to-creatinine ratio, a small but significant rise in LDL cholesterol, and significantly greater improvements in triglyceride levels and HDL cholesterol levels. Metformin plus SU was associated with a significant reduction in LDL cholesterol. SU plus pioglitazone is an effective and well-tolerated combination regimen that may provide additional beneficial effects for patients with type 2 diabetes.