title: Meta-analysis: metformin treatment in persons at risk for diabetes mellitus.
abstract: OBJECTIVE
  We performed a meta-analysis of randomized controlled trials to assess the effect of metformin on metabolic parameters and the incidence of new-onset diabetes in persons at risk for diabetes.
  
  
  METHODS
  We performed comprehensive English- and non-English-language searches of EMBASE, MEDLINE, and CINAHL databases from 1966 to November of 2006 and scanned selected references. We included randomized trials of at least 8 weeks duration that compared metformin with placebo or no treatment in persons without diabetes and evaluated body mass index, fasting glucose, fasting insulin, calculated insulin resistance, high-density lipoprotein cholesterol, low-density lipoprotein cholesterol, triglycerides, and the incidence of new-onset diabetes.
  
  
  RESULTS
  Pooled results of 31 trials with 4570 participants followed for 8267 patient-years showed that metformin reduced body mass index (-5.3%, 95% confidence interval [CI], -6.7--4.0), fasting glucose (-4.5%, CI, -6.0--3.0), fasting insulin (-14.4%, CI, -19.9--8.9), calculated insulin resistance (-22.6%, CI, -27.3--18.0), triglycerides (-5.3%, CI, -10.5--0.03), and low-density lipoprotein cholesterol (-5.6%, CI, -8.3--3.0%), and increased high-density lipoprotein cholesterol (5.0%, CI, 1.6-8.3) compared with placebo or no treatment. The incidence of new-onset diabetes was reduced by 40% (odds ratio 0.6; CI, 0.5-0.8), with an absolute risk reduction of 6% (CI, 4-8) during a mean trial duration of 1.8 years.
  
  
  CONCLUSIONS
  Metformin treatment in persons at risk for diabetes improves weight, lipid profiles, and insulin resistance, and reduces new-onset diabetes by 40%. The long-term effect on morbidity and mortality should be assessed in future trials.
authors.affiliation: Santa Clara Valley Medical Center, San Jose, CA 95128, USA. salpeter@stanford.edu
authors.forename: Shelley R
authors.initials: SR
authors.lastname: Salpeter
authors.forename: Nicholas S
authors.initials: NS
authors.lastname: Buckley
authors.forename: Justin A
authors.initials: JA
authors.lastname: Kahn
authors.forename: Edwin E
authors.initials: EE
authors.lastname: Salpeter
mesh_terms: D000328:Adult; D001786:Blood Glucose / Q000187:drug effects; D015992:Body Mass Index; D003920:Diabetes Mellitus / Q000097:blood / Q000453:epidemiology / Q000517:prevention & control*; D006801:Humans; D007004:Hypoglycemic Agents / Q000627:therapeutic use*; D007333:Insulin Resistance; D008074:Lipoproteins / Q000097:blood / Q000187:drug effects; D008687:Metformin / Q000627:therapeutic use*; D008875:Middle Aged; D015995:Prevalence; D012307:Risk Factors; D016896:Treatment Outcome
chemical_list: D001786:Blood Glucose; D007004:Hypoglycemic Agents; D008074:Lipoproteins; D008687:Metformin