Phentermine–topiramate extended-release plus lifestyle modification reduced weight and progression to type 2 diabetes mellitus in overweight or obese patients with prediabetes and/or the metabolic syndrome. In the 108-week, phase III trial of 475 patients, progression to type 2 diabetes mellitus was reduced by 71% and 79% in groups receiving two different doses of phentermine–topiramate extended-release, compared with that in the placebo group.