HbA_1c and the risks for all-cause and cardiovascular mortality in the general Japanese population: NIPPON DATA90

Objective - Associations between HbA_1c and cardiovascular diseases (CVD) have been reported mainly in Western countries. It is not clear whether HbA_1c measurements are useful for assessing CVD mortality risk in East Asian populations. Research Design and Methods - The risk for cardiovascular death was evaluated in a large cohort of participants selected randomly from the overall Japanese population. A total of 7,120 participants (2,962men and 4,158 women; mean age 52.3 years) free of previous CVD were followed for 15 years. Adjusted hazard ratios (HRs) and 95% CIs among categories of HbA_1c (<5.0%, 5.0-5.4%, 5.5-5.9%, 6.0-6.4%, and ≥6.5%) for participants without treatment for diabetes and HRs for participants with diabetes were calculated using a Cox proportional hazards model. Results - During the study, there were 1,104 deaths, including 304 from CVD, 61 from coronary heart disease, and 127 from stroke (78 from cerebral infarction, 25 from cerebral hemorrhage, and 24 from unclassified stroke). Relations to HbA_1c with all-cause mortality and CVD death were graded and continuous, and multivariate-adjusted HRs for CVD death in participants with HbA_1c 6.0-6.4% and ≥6.5%were 2.18 (95% CI 1.22-3.87) and 2.75 (1.43-5.28), respectively, compared with participants with HbA_1c <5.0%. Similar associations were observed between HbA_1c and death from coronary heart disease and death from cerebral infarction. Conclusions - High HbA_1c levels were associated with increased risk for all-cause mortality and death from CVD, coronary heart disease, and cerebral infarction in general East Asian populations, as in Western populations.