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.