Pre-diabetes and the risk for cardiovascular disease: a systematic review of the evidence.

OBJECTIVES Our objective was to estimate the magnitude of the relative risk (RR) for cardiovascular disease associated with impaired fasting glucose (IFG) and impaired glucose tolerance (IGT) from published prospective observational studies. BACKGROUND Hyperglycemia is a known risk factor for cardiovascular disease. However, the magnitude of the RR for cardiovascular disease associated with IFG and IGT is unclear. METHODS We searched PubMed from 1997 through 2008 for relevant publications and performed a meta-analysis. RESULTS In 18 publications with information about IFG (110 to 125 mg/dl) (IFG 110), estimates of RR ranged from 0.65 to 2.50. The fixed-effects summary estimate of RR was 1.20 (95% confidence interval [CI]: 1.12 to 1.28). In 8 publications with information about IFG (100 to 125 mg/dl) (IFG 100), estimates of RR ranged from 0.87 to 1.40. The fixed-effects summary estimate of RR was 1.18 (95% CI: 1.09 to 1.28). In 8 publications with information about IGT, estimates of RR ranged from 0.83 to 1.34. The fixed-effects summary estimate of RR was 1.20 (95% CI: 1.07 to 1.34). Five studies combined IFG and IGT, yielding a fixed-effects summary estimate of RR of 1.10 (95% CI: 0.99 to 1.23). No significant difference between the summary estimates for men and women were detected (IFG 110: men: 1.17 [95% CI: 1.05 to 1.31], women: 1.30 [95% CI: 1.10 to 1.54]; IFG 100: men: 1.23 [95% CI: 1.06 to 1.42], women: 1.16 [95% CI: 0.99 to 1.36]). CONCLUSIONS Impaired fasting glucose and IGT are associated with modest increases in the risk for cardiovascular disease.