ESTIMATION OF GLOMERULAR-FILTRATION RATE IN TYPE-II (NON-INSULIN-DEPENDENT) DIABETES-MELLITUS PATIENTS

The aim of this research was to develop an estimation of glomerular fi ltration rates (GFRs) from a combination of simple parameters in a lar ge group of type II diabetic patients. We selected 122 newly presentin g, previously untreated, type II patients whose GFR was determined fro m the plasma clearance of Cr-51-ethylenediamine tetraacetic acid (Cr-5 1-EDTA) and simultaneous measurements of demographic variables, includ ing fasting plasma glucose concentration, HbA(1c), blood pressure, lip ids, age, weight, body-mass index, body surface area, urea, and plasma creatinine concentration. The actual GFR values were compared with es timated values obtained from multiple regression and the Cockroft-Gaui t equations. Out of all the demographic variables, only plasma creatin ine concentration (r = -0.56, p < 0.001), age (r = -0.50, p < 0.001), urea (r = -0.28, p < 0.01), and systolic blood pressure (r = -0.21, p < 0.05) showed significant correlations with the actual GFR values, fo r which the mean and standard deviation were 117.5 +/- 22.0 ml min(-1) x 1.73 m(-2). The estimated values are highly correlated with the act ual values (r = 0.70), having an identical mean value of 117 +/- 15.3 and an unbiased regression relation (y = 0.000 + 1.000x). As standard measurements of the GFR are very time consuming and expensive, the use of the simple equation GFR(1) = 218.1 -0.916 x Age -0.635 x Creatinin e is recommended. The classification of GFR values into three ranges h as also revealed the nonlinear characteristics of GFR in relation to o ther demographic variables: age and creatinine are the dominant variab les in the middle GFR range, while the body-mass index and urea are do minant in the high and low ranges, respectively.