Review: lifestyle or pharmacological interventions prevent or delay type 2 diabetes in people with impaired glucose tolerance.

In people with impaired glucose tolerance, do lifestyle or pharmacological interventions prevent or delay type 2 diabetes?METHODSData 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.Study selection and assessment: randomised controlled trials (RCTs) in any language that evaluated an intervention to delay or prevent type 2 diabetes in people with impaired glucose tolerance and assessed development of diabetes as an outcome. 21 RCTs met the selection criteria, and 17 RCTs (n =8084, mean age range 39-57 y, mean body mass index range 24-36 kg/ m[2], average follow up range 0.4-4.6 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 diabetes and adverse events.MAIN RESULTSMeta-analysis using a random effects model showed that both lifestyle interventions (diet, exercise, or both) and pharmacological interventions (oral diabetes drugs [acarbose, flumamine, glipizide, metformin, or phenformin] or an anti-obesity drug [orlistat] ) reduced the incidence of type 2 diabetes (table); 2 trials assessing troglitazone were excluded from the meta-analysis because the drug had been removed from several markets worldwide because of liver toxicity. In 1 trial, jiangtang bushen (a Chinese herbal) did not reduce diabetes (table). Adverse events related to pharmacological interventions (gastrointestinal and hypoglycaemic symptoms) were more common in the treatment groups (no statistical tests reported).CONCLUSIONIn people with impaired glucose tolerance, lifestyle or pharmacological interventions prevent or delay type 2 diabetes.