Review: Lifestyle or pharmacological interventions prevent or delay type 2 diabetes in impaired glucose tolerance.

M e t h o d s Data sources: MEDLINE (1966 to July 2006), EMBASE/Excerpta Medica (1980 to July 2006), Cochrane Central Register of Controlled Trials, Cochrane Database of Systematic Reviews (Issue 2, 2006), references of relevant articles, and experts in the field. Study selection and assessment: Randomized controlled trials (RCTs) that evaluated an intervention to delay or prevent type 2 DM in persons with impaired glucose tolerance and had an outcome measurement of diabetes. 21 RCTs met the selection criteria, and 17 RCTs (n = 8084, mean age range 39 to 57 y, mean body mass index range 24 to 36 kg/m2, average follow-up range 0.4 to 4.6 y) were included in the meta-analysis. Among the 17 RCTs, 8 had quality scores ≥ 3 out of 5 on the Jadad scale, and 2 had allocation concealment. Outcomes: Development of type 2 DM and adverse events. M a i n r e s u l t s Meta-analysis using a random-effects model showed that both lifestyle interventions (diet, exercise, or both) and pharmacologic interventions (oral diabetes drugs [acarbose, flumamine, glipizide, metformin, or phenformin] or an antiobesity drug [orlistat]) reduced the incidence of type 2 DM (Table); 2 RCTs assessing troglitazone were excluded from the meta-analysis because the drug had been removed from several markets worldwide because of liver toxicity. In 1 RCT, jiangtang bushen (a Chinese herb) did not reduce DM (Table). Adverse events related to the pharmacologic interventions (gastrointestinal and hypoglycemic symptoms) were more common in the treatment groups (no statistical tests reported).