Relationship between HbA1c and mortality in a Japanese population

Abstract

Aim/hypothesis: HbA1c concentrations are known to be associated with all-cause excess mortality risk in Caucasians. However, the relationship has not been clarified well in the Japanese. In addition, studies of the relationship between HbA1c and mortality from malignant neoplasms are scarce. Methods: HbA1c was measured for 3,710 people of a cohort composed of A-bomb survivors and controls. At baseline they were divided into five groups: a normal HbA1c group of 1,143 individuals with HbA 1c of <5.5%, a slightly high but normal HbA1c group of 1,341 individuals with HbA1c ≥5.5% to <6.0%, a slightly high HbA1c group of 589 individuals with HbA1c ≥6.0% to <6.5%, a high HbA1c group of 259 individuals with HbA1c ≥6.5%, and a group of 378 individuals known to have type 2 diabetes. Using a Cox proportional hazards model, hazard ratios based on comparisons with the normal HbA1c group were obtained. Results: During the observation period there were 754 deaths. For all-cause and cardiovascular disease mortality, a significant increase of the hazard ratio was observed for the slightly high HbA1c group. A similar increase in malignant neoplasm-related mortality was observed for both the high HbA1c group and the diabetes group. Conclusions/interpretation: Our results suggest that individuals in the Japanese population with HbA1c levels of 6% or more might have increased mortality risk. The results indicate that HbA 1c measurements should be sought even for people who have not been diagnosed with diabetes. © Springer-Verlag 2005.