Background: Little evidence exists on the role of homocysteine as a predictor of mortality in patients with type 2 diabetes. The aim of this study was to investigate whether elevated plasma homocysteine levels are independently associated with all-cause or cardiovascular mortality in patients with type 2 diabetes and coronary artery disease.
Methods: This is a prospective cohort study that included 507 patients with type 2 diabetes and angiographically proven coronary artery disease. Patients were divided into 2 groups according to homocysteine level above or below median value (12.4 micromol/L): the high homocysteine group (255 patients) and the low homocysteine group (252 patients). The primary end-point of the study was all-cause mortality.
Results: There were 103 deaths during a 4-year follow-up: 62 deaths in the high homocysteine group and 41 deaths in the low homocysteine group (Kaplan-Meier estimates of mortality 25.6% and 17.4%, respectively (odds ratio [OR] 1.53, 95% confidence interval [CI] 1.03-2.27, P=0.031). Sixty-two of 103 deaths (60.2%) were of cardiovascular origin: 37 deaths (14.5%) occurred in the high homocysteine group and 25 deaths (9.9%) occurred in the low homocysteine group (P=0.115). Cox proportional hazards model showed that plasma homocysteine was not an independent correlate of all-cause (adjusted hazard ratio [HR] 1.10, 95% CI 0.89-1.33; P=0.397 for 5 micromol/L increase in concentration) or cardiovascular (adjusted HR 1.04, 95% CI 0.80-1.36, P=0.753, for 5 micromol/L increase in concentration) mortality.
Conclusion: In patients with type 2 diabetes and coronary artery disease, elevated level of homocysteine is an associate of increased cardiovascular risk but not an independent predictor of cardiovascular mortality.