Correlation Level of HbA1с and postprandial glycemia in type 2 diabetes in the oral glucose tolerance test

Abstract

A number of today's analytical methods for postprandial glycemia in the oral glucose tolerance test (OGTT) still remain to be substantiated. The standard OGTT using 75 g of glucose was performed in 42 type 2 diabetes mellitus (DM-2) patients who received diet therapy. The concentration of Hb A1c has been found to correlate with absolute levels of glycemia during 1- and 2-hour OGTT. However, exclusion of fasting glycemia from the level of glycemia at 1 and 2 hours of OGTT leads to cession of the correlation of HbA1c with these values of the test. Only 7 out of the 8 today's parameters for calculating the areas under the glycemic curve in OGTT correlate with the level of HbA1c. Moreover, 5 out of these 7 parameters are equivalent (r - 1; p < 0.05). The recently proposed two new parameters for calculating the areas under the glycemic curve in OGTT, one of which is constant 6.1, have proved to be equivalent (r= 1; p < 0 05) and to be actually reduced to one. The correlation with Hb Ah holds if any other constants from 5 to 11 mmоl/l are inserted instead of the constant 6.1 for calculating the area, the highest coefficient correlation with Hb A1c is achieved at the constant equal to 6.1. The correlation usually detectable at DM-2 between the concentration of Hb A,c and the absolute level of postprandial glycemia (glycemic spike in particular) Is mainly determined by its implicit inclusion of fasting glycemia. A set of 4 nonequivalent OGTT parameters should be used when the relationship of diabetes mellitus complications to the OGTT parameters that correlate with HbA,cis studied. The constants 5.6 and 6.1 reflect different aspects of the development of complications in diabetes mellitus when they are included in the calculation of an area in OGTT.