title: A systematic review of drug therapy to delay or prevent type 2 diabetes.
abstract: OBJECTIVE
  To systematically review the evidence for the prevention of type 2 diabetes by pharmacological therapies.
  
  
  METHODS
  Randomized controlled trials and cohort studies examining the effect of oral hypoglycemic agents, antiobesity agents, antihypertensive agents, statins, fibrates, and estrogen on the incidence of type 2 diabetes were identified from MEDLINE, EMBASE, the Cochrane Controlled Trials Registry, and searches of reference lists. Two reviewers independently assessed studies for inclusion and performed data extraction.
  
  
  RESULTS
  Ten studies of oral hypoglycemic agents and 15 studies of nonoral hypoglycemic agents were found. Oral hypoglycemic agents and orlistat are the only drugs that have been studied in randomized controlled trials with diabetes incidence as the primary end point. In the largest studies of 2.5-4.0 years' duration, metformin (relative risk [RR] 0.69, 95% CI 0.57-0.83), acarbose (0.75, 0.63-0.90), troglitazone (0.45, 0.25-0.83), and orlistat (hazard ratio [HR] 0.63, 95% CI 0.46-0.86) have all been shown to decrease diabetes incidence compared with placebo; however, follow-up rates varied from 43 to 96%. Current evidence for statins, fibrates, antihypertensive agents, and estrogen is inconclusive. In addition, the critical question of whether drugs are preventing, or simply delaying, onset of diabetes remains unresolved.
  
  
  CONCLUSIONS
  Currently, no single agent can be definitively recommended for diabetes prevention. Future studies should be designed with diabetes incidence as the primary outcome and should be of sufficient duration to differentiate between genuine diabetes prevention as opposed to simple delay or masking of this condition.
authors.affiliation: Department of Medicine, 2E3.22 Walter C. Mackenzie HSC, University of Alberta Hospital, 8440-112th St., Edmonton, AB, Canada, T6G 2B7. rpadwal@ualberta.ca
authors.forename: Raj
authors.initials: R
authors.lastname: Padwal
authors.forename: Sumit R
authors.initials: SR
authors.lastname: Majumdar
authors.forename: Jeff A
authors.initials: JA
authors.lastname: Johnson
authors.forename: Janice
authors.initials: J
authors.lastname: Varney
authors.forename: Finlay A
authors.initials: FA
authors.lastname: McAlister
mesh_terms: D019440:Anti-Obesity Agents / Q000627:therapeutic use; D000959:Antihypertensive Agents / Q000627:therapeutic use; D003924:Diabetes Mellitus, Type 2 / Q000517:prevention & control*; D006801:Humans; D007004:Hypoglycemic Agents / Q000627:therapeutic use*; D007783:Lactones / Q000627:therapeutic use; D000077403:Orlistat; D016032:Randomized Controlled Trials as Topic; D015203:Reproducibility of Results
chemical_list: D019440:Anti-Obesity Agents; D000959:Antihypertensive Agents; D007004:Hypoglycemic Agents; D007783:Lactones; D000077403:Orlistat