Poor Glycemic Control a Major Factor in Overestimating GFR in Diabetics

In a Diabetes Care study of 40 diabetics and 40 non-diabetics, inulin clearance was not significantly different between the two groups, but each of three eGFR measures from the diabetic patients was significantly higher than that of the non-diabetic subjects. There were significant and positive correlations between the ratio of each eGFR/insulin clearance, hemoglobin A1c, and glycated albumin. New formulae for calculating eGFR corrected by the glycemic control indices were better than the original eGFR, particularly in diabetic patients. The findings suggest that eGFR overestimates insulin clearance as glycemic controls worsen, and eGFR corrected by hemoglobin A1c is clinically useful.