Influence of body weight on the performance of glomerular filtration rate estimators in subjects with type 2 diabetes.

The American Diabetes Association recommends estimation of glomerular filtration rate (GFR) (1) by either the Cockcroft-Gault (2) or the Modification of Diet in Renal Disease (MDRD) (3) equation in all patients with diabetes. The implication is that these equations provide similar results. Body weight is a numerator in the CockcroftGault equation; however, it is absent from the MDRD equation. This may explain some of the difference in the ability of these equations to estimate GFR in patients with type 2 diabetes, over 80% of whom are obese (4), and may lead to discrepancies in reporting of chronic kidney disease stage (5). Our study was designed to identify whether body weight may explain variability in performance between the Cockcroft-Gault and MDRD equations in patients newly diagnosed with type 2 diabetes.