['To investigate the efficacy and safety of miglitol vs. placebo in type 2 diabetic outpatients insufficiently controlled (HbA1c between 7.5 and 10.5%) with diet and metformin.', 'Patients treated with diet and metformin (1500-2250 mg/day) were randomized to receive additional treatment with either miglitol or placebo for 32 weeks. The dosages were force-titrated: 4 weeks at 25 mg miglitol t.i.d., 12 weeks at 50 mg miglitol t.i.d., and 16 weeks at 100 mg miglitol t.i.d. or matching placebo. If the highest dosage could not be tolerated, patients could be down-titrated to 50 mg t.i.d. The primary efficacy criterion was the change in glycated haemoglobin (HbA1c). Secondary efficacy parameters included fasting and 1 h postprandial blood glucose, serum insulin, and fasting and 1 h postprandial triglyceride levels. Safety and tolerability were evaluated by the incidence of adverse events and changes in vital signs or routine biochemical and haematological parameters.', 'One hundred and fifty-two patients were valid for the intent-to-treat (ITT) analysis. There was a significant decrease in HbA1c on adding miglitol to metformin compared to adding placebo (miglitol treatment effect, - 0.21%; placebo treatment effect, + 0.22%; p = 0.011). Postprandial blood glucose declined in both the miglitol/metformin and placebo/metformin groups with a statistically significant difference in favour of miglitol/metformin (end of treatment adjusted means 13.8 mmol/l for miglitol vs. 15.8 mmol/l for placebo, p = 0.0007). Adverse events (AEs) were reported by only 8% more patients in the miglitol/metformin group than placebo/metformin. No cases of hypoglycaemia were reported.'] Does miglitol combined with metformin improve glycaemic control in type 2 diabetes?