The metabolic effects of once daily extended-release metformin in patients with type 2 diabetes: a multicentre study

Aim: To investigate the effects of extended-release metformin (MXR) compared with immediate-release metformin (MIR) on post-prandial glycaemic excursion, chronic glycaemia, lipid profiles, insulin resistance and islet function in type 2 diabetes. Methods: A randomised, open-labelled, positive-controlled multicentre study was conducted on 150 Chinese patients with type 2 diabetes. After 2 weeks of run-in period with MIR, 150 subjects were randomised into MXR group and MIR group. The patients in MXR group were assigned to take MXR 1500 mg once daily after dinner, while the patients in MIR group were assigned to continue MIR 500 mg thrice daily after meals for 12 weeks. Standard meal tests were carried out at baseline and at the end of this study. Plasma glucose, serum insulin, HbA1c and lipid profiles were measured. Homeostasis model assessment (HOMA) was used to evaluate insulin resistance index (HOMA-IR) and islet beta-cell function index (HOMA-B). Results: Either MIR or MXR modestly, but significantly decreased HbA1c levels and body mass index (BMI) after 12 weeks of treatment. However, there were no significant differences between two groups. The post-prandial glycaemia at 120 min after a standard meal in MXR group was higher than in MIR group (11.02 +/- 3.08 mmol/l vs. 9.74 +/- 2.61 mmol/l, p < 0.05). Moreover, no differences in the areas under curve of insulin release response, HOMA-B, HOMA-IR and lipid profiles were found within or between groups after 12 weeks of treatment. Conclusion: The effects of once daily MXR on chronic glycaemia, BMI, lipid profiles, insulin resistance and islet function are comparable with that of thrice daily MIR in oriental population.