Mortality in adults with and without diabetes in a national cohort of the U.S. population, 1971-1993

Abstract

Objective: To examine 22-year mortality (1971-1993), causes of death, life expectancy, and survival in a national sample of diabetic and nondiabetic adults according to age, sex, and race.

Research design and methods: A representative national cohort of 14,374 adults aged 25-74 years was identified in 1971-1975 in the First National Health and Nutrition Examination Survey (NHANES I). Diabetes was ascertained by medical history interview. The cohort was followed for mortality through 1992-1993, with verification of vital status for 96.2% (n = 13,830). Causes of death were determined from death certificates.

Results: Diabetic subjects comprised 5.1% of the cohort and accounted for 10.6% of the deaths. Mortality for diabetic subjects increased from 12.4 per 1,000 person-years for those aged 25-44 years at baseline to 89.7 per 1,000 person-years for those aged 65-74 years. The age-adjusted mortality rate was 57% higher for diabetic men than for diabetic women; the rate was 27% higher for diabetic non-Hispanic blacks than for diabetic non-Hispanic whites. Mortality rates were highest for insulin-treated subjects and for those with > or = 15 years' duration of diabetes. Diabetes was listed on the death certificate as the underlying cause of death for only 7.7% of diabetic men and 13.4% of diabetic women. Considering multiple causes of death, heart disease was listed the most frequently and was present on 69.5% of death certificates of people with diabetes. Death rates were higher for diabetic than for nondiabetic subjects in all age, sex, and race groups. The relative risk of death (diabetic versus nondiabetic subjects) declined with age from a value of 3.6 for those aged 25-44 years at baseline to 1.5 for those aged 65-74 years. The relative risk was elevated in diabetic subjects for all major causes of death except malignant neoplasms. Survival of diabetic subjects was lower than that of nondiabetic subjects in all age, sex, and race groups. Median life expectancy was 8 years lower for diabetic adults aged 55-64 years and 4 years lower for those aged 65-74 years.

Conclusions: In this representative national sample of adults, mortality rates were higher for diabetic men than for diabetic women and for diabetic blacks than for diabetic whites. The study confirms the substantially higher risk of death, lower survival, and lower life expectancy of diabetic adults compared with nondiabetic adults.