Clinical Question: In patients with type 2 diabetes, what is the effect on cardiovascular outcomes of aiming for intensive blood glucose control?
Bottom Line: Tight control of blood glucose does not protect patients from dying prematurely, whether by any cause or by cardiovascular disease. Tight control might confer some protection against the development of cardiovascular disease, but even this likelihood is tenuous. Aiming for tight control doubles the likelihood a patient will experience hypoglycemia severe enough to require medical intervention.
Reference: Kelly TN, Bazzano LA, Fonseca VA, Thethi TK, Reynolds K, He J. Systematic review: Glucose control and cardiovascular disease in type 2 diabetes. Ann Intern Med 2009;151(6):394-403.
Study Design: Meta-analysis (randomized controlled trials)
Funding: Foundation Setting:Various (meta-analysis)
Synopsis: To conduct this study, the researchers searched only one database to find randomized controlled trials of treatment of type 2 diabetes in adults. Two reviewers independently selected studies for inclusion and abstracted the data. The identified the 5 large trials (N = 27,802) that evaluated the role of tight blood glucose control. One problem: They excluded the University Group Diabetes Project study, which found increased cardiovascular mortality associated with treatment with sulfonylureas. The tight control of type 2 diabetes does not decrease the risk of mortality or cardiovascular-related mortality, though it may have an effect on slightly reducing the risk of cardiovascular disease (relative risk = 0.90; 95% CI 0.83 - 0.98). Including only the 3 newer studies, which enrolled older patients who had longstanding diabetes, found no benefit to tight control. Aiming for tight control doubled the likelihood that patients would experience severe hypoglycemia requiring medical attention. This analysis included enough patients to demonstrate even small benefits in intense blood glucose control, if they exist.