Derivation of a new equation for estimating creatinine clearance by using fat-free mass and serum creatinine concentration in Korean patients with type 2 diabetes mellitus.

Aims: Equations to predict creatinine clearance (Ccr) or glomerular filtration rate have limitations in applying to a wide range of ethnicities with different fat-free mass (FFM). We aimed to determine the serum creatinine (Scr) concentrations that indicate renal insufficiency and formulate a new equation to estimate Ccr by a function of FFM in Korean type 2 diabetic patients.

Methods: Ccr was measured in 283 type 2 diabetic patients by 24-h urine collection. Receiver operating characteristic (ROC) curve was used to determine the Scr concentration corresponding to a Ccr of 60 mL min(-1) x 1.73 m(-2). A new equation to predict Ccr was derived by using Scr and FFM.

Results: The Scr concentration corresponding to a Ccr of 60 mL min(-1) x 1.73 m(-2) was 1.15 mg/dL in men and 0.95 mg/dL in women. The regression equation estimating the Ccr was expressed as (1.72 x FFM-0.23 x age)/Scr, and it showed a good correlation with the measured Ccr (r=0.718, P<0.001).

Conclusions: Scr concentrations indicating renal insufficiency in the Korean patients were considerably lower than those in Caucasians. The equation derived in this study would be more useful in Korean or other Asian type 2 diabetic patients.