Efficacy of once- or twice-daily extended release metformin compared with thrice-daily immediate release metformin in type 2 diabetes mellitus.

ABSTRACT

BACKGROUND: The extended-release formulation of metformin (MXR) prolongs drug absorption in the upper gastrointestinal tract and permits once-daily dosing in patients with type 2 diabetes mellitus (T2DM). This newer formulation may enhance patient compliance with oral therapy compared to conventional immediate-release metformin (MIR) in T2DM. OBJECTIVES: To analyse whether a switch from thrice daily MIR to once or twice daily MXR wouldachieve comparable degrees of glycemic control in patients with type 2 diabetes mellitus (T2DM). METHODS: We conducted an open study of the efficacy and tolerability of MXR in 40 patients with T2DM who had achieved moderate or good glycemic control with MIR alone or in combination with other antihyperglycemic agents. After a lead in period of 3 months patients were switched over to a specific brand of MIR at baseline (Visit 0). Patients were subsequently followed for 4 more visits. These visits were done monthly, after taking MIR in a dose of 1-2 g/day (Visit 1); MXR as a single dose at dinner but 0.5 g less than baseline dose of MIR (Visit 2); MXR, 1-2 g/day as a single dose at bedtime, with strength same as that of baseline dose of MIR (Visit 3); and MXR, 1-2 g/day in two divided doses keeping dose same as baseline MIR (Visit 4). Glycemic control was assessed by a four-point glucose profile (fasting and three postprandial levels) at each visit. RESULTS: At visit 2, when patients had been on 500 mg lesser dose of MXR for 1 month, glucose profile worsened. However, glycemic control, at visit 3, returned to earlier levels when dose of MXR was increased back to original dose. Overall the MXR formulation was well tolerated with minor gastrointestinal adverse effects, reported by only 3 patients. CONCLUSION: Patients with T2DM who had been receiving thrice-daily MIR achieved comparable glycemic control when therapy was switched to once- or twice-daily MXR at the same total daily dose.