THE EVALUTION ON HbA1c ON THE BASIS OF FASTING PLASMA GLUCOSE AND ORAL GLUCOSE TOLERANCE TEST TO DIAGNOSE DIABETES MELLITUS

Objective: To examine the relationship between fasting plasma glucose (FPG) and postprandial plasma glucose (PPG) and HbA1c which is used to monitore the efficacy of diabetes' treatment and to find the best cut-off value of HbA1c for Turkish people to diagnose diabetes. Material and Method: 150 women and 94 men who have applied to the internal medicine clinic were included to the study Oral glucose tolerance test (OGTT) was applied to patients with 75 g glucose. Finding cut-off points for HbA1c was performed by receiver operating characteristic ROC analysis. Results: On the basis of IFG and OGTT results, 33 patients were diagnosed with DM. Best cut off value of HbA1c for IFG was found to be 6.15%, sensitivity was 75% and specificity was 89.1% according to ROC analysis. For 2-hour OGTT plasma glucose levels best cut-off value of HbA1c was found to be 6.35%, sensitivity was 65.4% and specificity was 95%. Conclusion: It was found that using an HbA1c cut-off value (>= 6.5%) shows statistically significant correlation with high level of specificity in diagnosing DM. In predicting DM diagnosis, best cut-off value of HbA1c was found to be 6.15% for IFG and 6.35% for 2-hour OGTT plasma glucose levels.