Estimated glomerular filtration rate, albuminuria and mortality in type 2 diabetes: the Casale Monferrato Study

AIMS/HYPOTHESIS: Estimated glomerular filtration rate (eGFR) predicts mortality in non-diabetic populations, but its role in people with type 2 diabetes is unknown. We assessed to what extent a reduction in eGFR in people with type 2 diabetes predicts 11-year all-cause and cardiovascular mortality, independently of AER and other cardiovascular risk factors. MATERIALS AND METHODS: The study population was the population-based cohort (n = 1,538; median age 68.9 years) of the Casale Monferrato Study. GFR was estimated by the abbreviated Modification of Diet in Renal Disease Study equation. RESULTS: At baseline, the prevalence of chronic kidney disease (eGFR <60 ml min(-1) 1.73 m(-2)) was 34.3% (95% CI 33.0-36.8). There were 670 deaths in 10,708 person-years of observation. Hazard ratios of 1.23 (95% CI 1.03-1.47) for all-cause mortality and 1.18 (95% CI 0.92-1.52) for cardiovascular mortality were observed after adjusting for cardiovascular risk factors and AER. When five levels of eGFR were analysed we found that most risk was conferred by eGFR 15-29 ml min(-1) 1.73 m(-2), whereas no increased risk was evident in people with eGFR values between 30 and 59 ml min(-1) 1.73 m(-2). In an analysis stratified by AER categories, a significant increasing trend in risk with decreasing eGFR was evident only in people with macroalbuminuria. CONCLUSIONS/INTERPRETATION: Our study suggests that in type 2 diabetes macroalbuminuria is the main predictor of mortality, independently of both eGFR and cardiovascular risk factors, whereas eGFR provides no further information in normoalbuminuric people.