Triple therapy with glimepiride in patients with type 2 diabetes mellitus inadequately controlled by metformin and a thiazolidinedione: Results of a 30-week, randomized, double-blind, placebo-controlled, parallel-group study

Objective: This study evaluated the efficacy and tolerability of glimepiride in patients with type 2 diabetes mellitus that was inadequately controlled with a combination of immediate- or extended-release metformin and a thiazolidinedione. Methods: This was a multicenter, randomized, double-blind, placebo-controlled, parallel-group, 2-arm study consisting of a 4-week stabilization and eligibility period and a 26-week treatment period. Patients with a diagnosis of type 2 diabetes for a minimum of 1 year received glimepiride (titrated sequentially from 2 to 4 to 8 mg/d over 6 weeks, followed by 20 weeks of maintenance therapy) or placebo in combination with an established regimen of immediate- or extended-release metformin and rosiglitazone or pioglitazone. The primary efficacy outcome was the change in glycosylated hemoglobin (HbA(1c)) from baseline. The safety analysis was based on the incidence of hypoglycemia, adverse events, and laboratory abnormalities. Changes in lipid levels (high-density lipoprotein cholesterol, total cholesterol, low-density lipoprotein cholesterol, very low density lipoprotein cholesterol, and triglycerides) were evaluated, and health-related quality of life was assessed based on scores on the Diabetes Care Profile (DCP) and Health Utilities Index Mark 3 (HU13). Results: Of 170 randomized patients, 159 were included in the efficacy analysis and 168 were included in the safety analysis. Demographic variables were similar at baseline between the glimepiride and placebo groups (mean age, 56.5 and 56.4 years, respectively; percent men/women, 61.0%/39.0% and 62.3%/ 37.7%; weight, 100.9 and 96.3 kg). HbA(1c) was significantly improved at end point with glimepiride combination therapy compared with placebo (mean [SE], -1.31% [0.08] vs -0.33% [0.08], respectively; P < 0.001). The majority of patients (62.2%) who received glimepiride achieved an HbA(1c) val ue of .57%, compared with 26.0% of patients receiving placebo (P < 0.001 between groups). At end point, the adjusted mean differences between treatments significantly favored the glimepiride combination in terms of fasting plasma glucose (-37.4 [4.0] mg/dL; P < 0.001), fasting insulin (4.06 [1.691 mu IU/mL; P < 0.03), and C-peptide (124.5 [35.9] pmol/L; P < 0.001). The adjusted mean changes in body mass index from baseline to end point were 1.26 (0.16) kg/m(2) with glimepiride and 0.17 (0.16) kg/m(2) with placebo (P < 0.001). Similarly, the mean change in weight was greater with glimepiride than with placebo (3.76 [0.54] vs 0.45 [0.52] kg; P < 0.001). There were no significant differences in lipid levels between groups. Clinically significant adverse events, laboratory abnormalities, and rates of severe hypoglycemia were similar between treatment groups. The overall incidence of hypoglycemia, however, was 51.2% in the glimepiride group and 8.3% in the placebo group (P < 0.001). In general, there was no significant difference between treatment groups with respect to scores on the DCP or HU13 over the study period. Conclusions: In these patients with type 2 diabetes that was not adequately controlled by dual combination therapy with metformin and a thiazolidinedione, the addition of glimepiride improved glycemic control compared with placebo with an acceptable tolerability profile. Although there were significantly more episodes of hypoglycemia with triple therapy than with dual therapy and placebo, the risk for severe hypoglycemia was low.