Renal damage in patients with Type 2 diabetes: a strong predictor of mortality.

Aims: (i) To compare mortality rates in a cohort of Type 2 diabetic patients with those of the general population; (ii) to assess the prognostic role of pre-existing chronic conditions; (iii) to evaluate the impact of different severity of renal damage on mortality.

Methods: All 3892 patients with Type 2 diabetes attending our Diabetic Clinic during 1995 and alive on 1 January 1996 were identified and followed for 4.5 years. Information on vital status (100% complete) and causes of death (98.5% complete) for 599 deceased subjects was derived from death certificates.

Results: In comparison with the general population, standardized mortality ratios (x 100) were: 125 (95% confidence interval 104-148) in patients aged < 75 and 85 (75-95) in patients > or = 75 years. Cardiovascular diseases and diabetes were responsible for most of the excess deaths. In a Cox-proportional hazard model, renal damage was a powerful predictor of death (hazard ratio = 2.39; 95% confidence intervals = 2.00-2.85). The severity of renal damage was associated with increasing hazard ratios for death from all-cause mortality and from specific causes (especially coronary artery disease, other cardiovascular causes and diabetes) after multiple adjustments. Other significant predictors of death were: greater age, glycated haemoglobin, smoking, lower body mass index, pre-existing coronary and peripheral artery disease and known co-morbidity (cirrhosis and cancer).

Conclusions: Renal damage of any severity is significantly associated with subsequent mortality from all causes and from cardiovascular diseases. These associations are not confounded by pre-existing co-morbidity or coronary diseases.