Diabetes, mortality and coronary heart disease in the prospective Dubbo study of Australian elderly

Background: A prospective study of Australian elderly living in Dubbo has shown that diabetes is a significant predictor of all-causes mortality and coronary heart disease (CHD). Aim: To examine and contrast clinical and socio-demographic predictors of these outcomes in those with and without diabetes. Methods: The data are derived from a community-based sample of subjects 60 years and older followed over 62 months since 1988. Of 1155 men and 1472 women, 9.2% and 6.9% respectively manifested diabetes at baseline, based on history or fasting hyper-glycaemia. Results: In the presence of diabetes, all-causes mortality was increased twofold in both sexes, CHD incidence was increased twofold in men and threefold in women, stroke incidence was increased twofold in women but little changed in men. Proportional hazards models were derived separately for persons with and without diabetes and risk factors differentially predictive in diabetes were sought. Significant predictors of death in diabetes were old age and current smoking. Those factors differentially predictive were ‘being married’ (Relative Risk RR] 1.60 with diabetes and 0.69 without diabetes) and higher body mass index (BMI) (RR 1.03 with diabetes and 0.79 without diabetes). Significant predictors of CHD in diabetes were old age, prior CHD, severe hypertension, low HDL cholesterol and self-rated health. Those factors differentially predictive were higher body mass index (RR 1.14 vs 0.83) and physical disability (RR 0.69 vs 1.55). Differential predictions with regard to BMI may relate in part to excess CHD and mortality at low BMI in non-diabetic subjects. Conclusion: The vascular disease burden of diabetes in the elderly has been confirmed, especially in women. A number of conventional risk factors are contributing to this burden and may be amenable to treatment.