: • Canadian Family Physician • Le Médecin de famille canadien ratiqu cliniqu linica ra ic

J Med 2002;346(6):393-403. Research question Does lifestyle intervention or treatment with metfor-min prevent or delay onset of type 2 diabetes in high-risk patients (ie, overweight people with high fasting glucose levels and impaired glucose tolerance)? Do these two interventions diff er in eff ectiveness? Type of article and design Randomized, double-blind (for the placebo and metformin intervention), placebo-controlled trial. Relevance to family physicians Type 2 diabetes is extremely common in our prac-tices, as are obese people. In 2002, we reviewed the Finnish Diabetes Prevention Trial1 that was simi-lar to this trial, but looked only at lifestyle. It had very promising results.2 Briefl y, participants made four changes: they reduced total and saturated fat intake, were active 150 minutes weekly, lost 5 % of their weight, and consumed more fi bre. In that and this trial, progression to type 2 diabetes was pre-vented in 58 % of participants during the 3 years of the trial. We know that patients struggle with dys-glycemia before they meet current criteria for type 2 diabetes and that some patients are incapable of making lifestyle changes at a given time. Would medications also help “prevent ” diabetes, and to what degree compared with lifestyle changes? Overview of study and outcomes This clinical trial in 27 centres looked at over-weight people (mean age 50 years, mean body mass index [BMI] 34) who had impaired glucose tolerance (plasma glucose concentration of 7.8 to 11.0 mmol/L 2 hours after a 75-g oral glucose load) and impaired fasting glucose (plasma glucose con-centration of 5.3 to 6.9 mmol/L fasting). About 45% of participants were African-American, Hispanic, Native American, or Asian; 68 % were women. The 3234 participants were assigned to one of three interventions: standard lifestyle recommenda-tions plus 850 mg of metformin twice daily, standard lifestyle recommendations plus placebo twice daily, or an intensive program of lifestyle modification. Standard lifestyle recommendations were provide