Lipid but not glycaemic parameters predict total mortality from type 2 diabetes mellitus in Canterbury, New Zealand

A cohort of 447 subjects with Type 2 diabetes mellitus (208 male, 239 female; age range 30-82, median 62 years; and of predominantly European origin) was characterized in a clinic survey in 1989. Individual status (dead or alive) at 1 June 1995 was ascertained. Mortality rates were compared with the general New Zealand population by calculating standardized mortality ratios (SMR) and the hazard ratio (HR) of prognostic factors evaluated with Cox's proportional hazards model. At 6 years, 289 subjects were confirmed as alive and 133 as dead; only 25 were untraceable. Six-year survival for the cohort was 70% (95% CI 66-74). SMR was 2.53 (95% CI 1.99-2.68) for the female cohort and 2.03 (95% CI 1.60-2.59) for the male cohort. Factors assessed at baseline (1989) that were independently prognostic of total mortality included age, male sex, pre-existing coronary artery disease (CAD) (HR 2.2, 95% CI 1.5-3.3) and plasma cholesterol (HR for 1.4 mmol l(-1) change: 1.49, 95% CI 1.2-1.9). HDL-cholesterol was protective in women (HR for 0.4 mmol l(-1) change: 0.72, 95% CI 0.51-1.00) but not men. Glycated haemoglobin was not a significant predictor of total mortality. Predictors of CAD mortality (in those subjects free of CAD in 1989) included plasma cholesterol (HR for 1.4 mmol l(-1) change: 1.86 95% CI 1.20-2.89), glycated haemoglobin (HR for 1.8% change: 1.9 95% CI 1.04-3.47), male sex, peripheral vascular disease, and smoking. There is therefore increased mortality in Type 2 diabetic subjects in Canterbury, New Zealand. HDL-cholesterol is protective against total mortality in females.