Meta-analysis of the effects of statin therapy on endothelial function in patients with diabetes mellitus.

BACKGROUND

Controversies exist among trials reporting the effects of statins on endothelial dysfunction in patients with diabetes mellitus (DM). Therefore, we performed a meta-analysis to determine whether statin therapy could improve endothelial dysfunction in patients with DM.

METHODS

PubMed, Cochrane and Embase were searched for randomized controlled trials of statins. Only trials reporting changes in flow-mediated dilatation (FMD) were included in this analysis. A meta-analysis was performed to assess the relationship between statin therapy and improvements in endothelial dysfunction. Meta-regression and subgroup analyses were done to identify sources of heterogeneity.

RESULTS

Ten statin studies (845 patients) were included in this analysis. Statin therapy significantly improved FMD in patients with DM [weighted mean difference (WMD): 0.94%; 95% CI: 0.38%, 1.5%; P<0.001]. Although heterogeneity among trials was found (I(2): 67%), no significant publication bias was detected. Subgroup analyses showed that patients did not benefit from statin therapy if their body mass index (BMI) was>27.6 kg/m(2) (four trials; I(2): 0%; WMD: 0.11%; 95% CI: -0.47%, 0.70%; P=0.70). However, FMD was significantly improved among patients with BMI ≤27.6 kg/m(2) (five trials; I(2): 14%; WMD: 1.52%; 95% CI: 1.19%, 1.85%; P<0.001). Type 1 diabetes, younger age, lower baseline blood lipid levels and blood pressure were all associated with improvements in FMD. The meta-regression analysis yielded similar results.

CONCLUSION

Statins significantly improved the FMD only in patients with better endothelial functions. The use of FMD in evaluating therapeutic outcomes should be careful in populations at high risk.