Patients with type 2 diabetes having higher glomerular filtration rate showed rapid renal function decline followed by impaired glomerular filtration rate: Japan Diabetes Complications Study.

AIMS: The Japan Diabetes Complications Study (JDCS), a nation-wide, multicenter, prospective study of patients with type 2 diabetes, reported that hemoglobin A1c (HbA1c ), systolic blood pressure, and smoking were risk factors for the onset of macroalbuminuria. This study explored the risk factors for glomerular filtration rate (GFR) decline in the JDCS patients.

METHODS: We examined the 1407 JDCS patients (667 women, mean age 59years, 974 normoalbuminuria, 433 microalbuminuria) whose urinary albumin-to-creatinine ratio (UACR) and estimated GFR (eGFR) were determined at baseline with an 8-year follow-up. We divided all the patients into four groups according to baseline eGFR: G1 (120≤eGFR), G2 (90≤eGFR<120), G3 (60≤eGFR<90), G4 (eGFR<60).

RESULTS: The eGFRs in groups G1 and G2 decreased at follow-up compared to those at the baseline. The risk of annual eGFR decline rate≥3ml/min/1.73m2 (rapid decliners) increased as the baseline eGFR increased. Advanced age, high HbA1c , and UACR, or diabetic retinopathy at baseline were risk factors for the rapid decliners. Especially the G1 group had a significant risk for the rapid decliners. The frequency of the patients with GFR<60ml/min/1.73m2 at the follow-up amounted to 31.1% in the rapid decliners, which was higher than 12% in the non-rapid decliners.

CONCLUSIONS: In normo- and microalbuminuric patients with type 2 diabetes, extra careful attention should be paid to patients with eGFR ≥120ml/min/1.73m2 to detect cases with rapidly decreased GFR under the normal range.