Long-term effects of glimepiride or rosiglitazone in combination with metformin on blood pressure control in type 2 diabetic patients affected by the metabolic syndrome: a 12-month, double-blind, randomized clinical trial

Abstract

Background: Some evidence suggests that antihyperglycemic drugs might have a small but clinically significant beneficial effect on blood pressure in patients with diabetes mellitus. Based on a literature search, few direct comparisons of different antihyperglycemic treatments on blood pressure have been reported.

Objectives: The primary aim of the present study was to compare the effect of long-term (12-month) combination treatment with glimepiride or rosiglitazone plus metformin on blood pressure in patients with type 2 diabetes mellitus (DM-2) and the metabolic syndrome. Secondary end points were glycemic control and improvement in insulin sensitivity.

Methods: This randomized, double-blind study was conducted at 2 centers in Italy. Patients aged > or =18 years with DM-2 and the metabolic syndrome and poor glycemic control (insulin resistance) with monotherapy with the maximum tolerated dose of an antihyperglycemic agent (eg, a sulfonylurea, metformin) were enrolled. All patients received 12 months of oral treatment with metformin 500 mg TID plus glimepiride 2 mg QD (G + M) or rosiglitazone 4 mg QD (R + M). Blood pressure, heart rate (HR), and body mass index (BMI); plasma levels of fasting and postprandial glucose and insulin (FPG, PPG, FPI, and PPI, respectively) and glycosylated hemoglobin (HbA(1c)); and homeostasis model assessment (HOMA) index were determined at 0 (baseline), 3, 6, 9, and 12 months of treatment. Adverse effects (AEs) were assessed using spontaneous reporting, patient interview, and laboratory analysis.

Results: Ninety-nine patients were enrolled in the study; 95 completed it (48 men, 47 women; mean age, 54 years [range, 47-58 years]; G + M, 47 patients; R + M, 48 patients). Four patients did not complete the study due to noncompliance (2 patients in the R + M group), protocol violation (1 patient in the G + M group), and loss to follow-up (1 patient in the G + M group). Mean blood pressure values were not significantly improved in the G + M group at any time point, whereas these values were significantly improved at 12 months in the R + M group. Mean BMI, HbA(1c), FPG, and PPG were significantly decreased from baseline in both groups at 12 months (all, P < or = 0.05). Mean FPI, PPI, and HOMA index were significantly improved at 12 months only in the R + M group (all, P < or = 0.05 vs baseline); these changes were not found in the G + M group. No significant changes in HR were found. Headache and flatulence were reported in both groups (G + M, 2 patients each; R + M, 1 and 2 patients, respectively), but these AEs were mild and transient. In the R + M group, liver enzyme levels were increased to 1.5-fold the upper limit of normal in 3 patients, but were normalized by study end.

Conclusions: In this study in patients with DM-2 and the metabolic syndrome, long-term (12-month) combination treatment with R + M, but not G + M, was associated with a significant improvement in blood pressure control. Improvements in glycemic control and insulin resistance-related parameters were found at 9 months with R + M, compared with 12 months with G + M. Both treatments were well tolerated.