Diabetes mellitus as a cause or comorbidity of chronic kidney disease and its outcomes: the Gonryo study

Background Diabetes mellitus (DM) is a major cause of end-stage kidney disease (ESKD). However, the difference in renal outcomes between DM patients with non-diabetic renal disease (DM and NDRD) and those with diabetic nephropathy (DN) is controversial. The aim of the present study was to evaluate the differences among patients with DN, DM, and NDRD, and non-DM chronic kidney disease (CKD) in a prospective observational study. Methods We extracted the data of 2484 patients from 11 nephrology care centers and categorized into three groups as described above. The primary outcome was ESKD requiring renal replacement therapy. Results During the median follow-up of 4.44 years, 281 patients (11.3%) developed ESKD. Renal outcomes of DM and NDRD patients were similar to those of non-DM patients ( p ≥ 0.05). At CKD stage G3b, the hazard ratios (95% confidence intervals) of ESKD were 7.10 (2.46–20.49) in DN patients and 0.89 (0.19–4.24) in DM and NDRD. The annual change in the estimated glomerular filtration rate (eGFR) in DN patients was significantly larger than that in other groups at stage G3b (−9.7%/year). Conclusions We found that DN patients have a higher risk for ESKD than DM and NDRD or non-DM patients. In particular, GFR rapidly declined in DN at stage G3b. DM and NDRD patients can accomplish equally beneficial renal outcomes as non-DM CKD, regardless of their similar metabolic profiles as DN. In conclusion, we should prudentially consider the risk stratification of DM whether cause or comorbidity of CKD.