Aims/hypothesis: Microvascular complications are a common feature of diabetes but additional research is needed regarding diabetic nephropathy endpoints in type 1 and type 2 diabetes.
Methods: We compared 277 type 1 diabetes patients with 942 type 2 diabetes patients, with clinical proteinuria and no endstage renal disease (ESRD) at baseline, prospectively followed for death, ESRD and decline in estimated glomerular filtration rate (eGFR, all available measures).
Results: The incidence rate of death was 67.0 (95% CI 59.2, 74.8) vs. 24.6 (95% CI, 19.0, 30.2) per 1,000 patient-years, in type 2 diabetes and type 1 diabetes, respectively. Unadjusted risk for death was greater for type 2 diabetes patients (HR 3.423; 95% CI, 2.501, 4.683; p<0.0001), but the difference did not persist after adjustment for age (HRage-adj 0.859; 95% CI 0.581, 1.269; p=0.445). The incidence rate of ESRD was 18.4 (95% CI 14.2, 22.5) vs. 47.1 (95%CI 38.4, 55.9) per 1,000 patient-years, in type 2 diabetes and type 1 diabetes, respectively. Unadjusted risk for ESRD was lower in type 2 diabetes (HR 0.399; 95% CI 0.287, 0.554; p<0.0001), but the difference did not persist after adjustment for sex, age and baseline serum creatinine (HRadj 0.989; 95% CI 0.597, 1.639; p=0.965). In a mixed linear model, eGFR decline was not significantly different in type 2 vs. type 1 diabetes (difference in slope −0.19 [0.28] ml min(−1) 1.73 m(−2) year(−1); p=0.512).
Conclusions/interpretation: In diabetic nephropathy, once baseline risk factors were taken into account the risk for death, ESRD and renal function decline did not significantly differ between type 1 diabetes and type 2 diabetes.