Independent risk factors of rapid glomerular filtration rate decline in patients with type 2 diabetes with preserved kidney function and normoalbuminuria: A multicenter cohort study

Aims/introduction: Research on the incidence and underlying mechanisms of rapid renal function decline in patients with type 2 diabetes mellitus with preserved renal function and normoalbuminuria is limited. This study aimed to investigate the involvement of hemoglobin level as a risk factor for rapid decliners among patients with type 2 diabetes with preserved renal function and normoalbuminuria.

Materials and methods: This was a retrospective observational study of 242 patients with type 2 diabetes with a baseline estimated glomerular filtration rate of ≥60 mL/min/1.73 m² and normoalbuminuria (<30 mg/gCr), followed up for >1 year. The annual rate of estimated glomerular filtration rate decline during the follow-up period was calculated using least square regression analysis; rapid decliners defined at ≥3.3%/year. Risk factors associated with rapid decliners were identified using a logistic regression analysis of variables previously identified as risk factors of rapid decliners.

Results: The median follow-up period was 6.7 years, and 34 patients showed rapid decliners. On multivariate analysis, lower baseline hemoglobin level was a risk factor of rapid decliners (odds ratio 0.69, 95% confidence interval 0.47-0.99; P = 0.045). Furthermore, the baseline hemoglobin levels were correlated positively with iron and ferritin levels, implying that an impaired iron metabolism might cause lower hemoglobin levels in rapid decliners.

Conclusions: In patients with type 2 diabetes with preserved renal function and normoalbuminuria, lower hemoglobin levels were a risk factor for rapid decliners, where disturbed iron metabolism might precede the development of diabetic kidney disease.