Diabetes duration and cause-specific mortality in the Verona Diabetes Study

OBJECTIVE - To examine the 10-year mortality and effect of diabetes duration on overall and cause-specific mortality in diabetic subjects in the Verona Diabetes Study (VDS). RESEARCH DESIGN AND METHODS - Records from diabetes clinics, family physicians, and a drug consumption database were used to identify 5,818 subjects greater than or equal to 45 years of age with type Z diabetes who were alive and residing in Verona, Italy on 31 December 1986. Vital status of each subject was ascertained on 31 December 1996. Underlying causes of death were determined from death certificates. Death rates and death rate ratios (DRRs) were computed and standardized to the population of Verona in 1991. RESULTS- During the study, 2,328 subjects died; 974 deaths were attributable to cardiovascular disease, 517 to neoplasms, 324 to diabetes-related diseases, 134 to digestive diseases, 250 to other natural causes, and 48 to external causes. There were 81 subjects who died of unknown causes. Death rates from natural causes were higher in men than in women (DRR 1.4, 95% CI 1.2-1.5) and rose in both sexes with increasing duration of diabetes (P = 0.001). Among the natural causes of death, those for diabetes-related diseases were strongly related to diabetes duration (P = 0.001); a modest relationship with duration was also found for ischemic heart disease in men (P = 0.07). CONCLUSIONS - Cardiovascular disease was the principal cause of death among people with type 2 diabetes in the VDS. Rates for natural causes of death rose with increasing duration of diabetes. Deaths from diabetes-related diseases in both sexes and from ischemic heart disease in men were largely responsible for this increase.