Estimation of glomerular filtration rate in type II (non-insulin dependent) diabetes mellitus patients

Abstract

The aim of this research was to develop an estimation of glomerular filtration rates (GFRs) from a combination of simple parameters in a large group of type II diabetic patients. We selected 122 newly presenting, previously untreated, type II patients whose GFR was determined from the plasma clearance of ⁵¹Cr-ethylenediamine tetraacetic acid (⁵¹Cr -EDTA) and simultaneous measurements of demographic variables, including fasting plasma glucose concentration, HbA_1c, blood pressure, lipids, age, weight, body-mass index, body surface area, urea, and plasma creatinine concentration. The actual GFR values were compared with estimated values obtained from multiple regression and the Cockroft–Gault equations. Out of all the demographic variables, only plasma creatinine 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, for which the mean and standard deviation were 117.5± 22.0 ml min⁻¹ × 1.73 m⁻². The estimated values are highly correlated with the actual values (^r = 0.70), having an identical mean value of 117±15.3 and an unbiased regression relation (y = 0.000 + l.000x). As standard measurements of the GFR are very time consuming and expensive, the use of the simple equation GFR₁ =218.1− 0.916 × Age − 0.635 − Creatinine is recommended. The classification of GFR values into three ranges has also revealed the nonlinear characteristics of GFR in relation to other demographic variables: age and creatinine are the dominant variables in the middle GFR range, while the body-mass index and urea are dominant in the high and low ranges, respectively.

glomerular filtration rate, creatinine, multiple regression, Cockroft-Gault equation, renal function.