Association between glycosylated hemoglobin level and cardiovascular and all-cause mortality in type 1 diabetes

Hyperglycemia is implicated in the development and progression of microvascular complications in type 1 diabetes. In contrast, the association between hyperglycemia and macrovascular complications or mortality in type 1 diabetes is not clear. The authors studied a population-based cohort of 879 individuals with type 1 diabetes from Wisconsin, free of cardiovascular disease and end-stage renal disease at the baseline examination (1980-1982). The main outcome of interest was all-cause (n = 201) and cardiovascular (n = 132) mortality as of December 31, 2001. Elevated glycosylated hemoglobin levels were associated with all-cause and cardiovascular mortality, independent of duration of diabetes, smoking, hypertension, and proteinuria. The multivariable relative risks comparing the highest quartile of glycosylated hemoglobin (>= 12.1%) with the lowest quartile (<= 9.4%) were 2.42 (95% confidence interval: 1.54, 3.82; p-trend = 0.0006) for all-cause mortality and 3.28 (95% confidence interval: 1.77, 6.08; p-trend < 0.0001) for cardiovascular mortality. This association was present among both sexes and persisted in subgroup analyses by categories of diabetes duration, smoking, body mass index, proteinuria, and retinopathy. These data suggest that hyperglycemia is associated with all-cause and cardiovascular mortality among individuals with type 1 diabetes.