Background: The increased prevalence of type 2 diabetes mellitus is a major concern for health providers. We therefore assessed whether voglibose, an alpha-glucosidase inhibitor, could prevent the development of type 2 diabetes in high-risk Japanese individuals with impaired glucose tolerance.
Methods: 1780 eligible patients on a standard diet and taking regular exercise with impaired glucose tolerance were randomly assigned to oral voglibose 0.2 mg three times a day (n=897) or placebo (n=883) in a multicentre, double-blind, parallel group trial. Treatment was continued until participants developed type 2 diabetes (primary endpoint) or normoglycaemia (secondary endpoint), or for a minimum of 3 years, subject to the findings of an interim analysis. Analysis was by full analysis set. This trial is registered with the University Hospital Medical Information Network (UMIN) clinical trials registry, number UMIN 000001109.
Findings: In the interim analysis, voglibose was better than placebo (p=0.0026) in individuals treated for an average of 48.1 weeks (SD 36.3). Patients treated with voglibose had a lower risk of progression to type 2 diabetes than did those on placebo (50 of 897 vs 106 of 881; hazard ratio 0.595, 95% CI 0.433-0.818; p=0.0014). More people in the voglibose group achieved normoglycaemia than did those in the placebo group (599 of 897 vs 454 of 881; 1.539, 1.357-1.746; p<0.0001). 810 (90%) of 897 patients in the voglibose group had adverse events versus 750 (85%) of 881 in the placebo group. Serious adverse events (all one each) in the voglibose group were cholecystitis, colonic polyp, rectal neoplasm, inguinal hernia, liver dysfunction, and subarachnoid haemorrhage, and in the placebo group were cerebral infarction and cholecystitis.
Interpretation: Voglibose, in addition to lifestyle modification, can reduce the development of type 2 diabetes in high-risk Japanese individuals with impaired glucose tolerance.