Low association between fasting and OGTT stimulated glucose levels with HbA1c in overweight children and adolescents

Background Diabetes and prediabetes are defined based on different methods such as fasting glucose, glucose at 2-hour in oral glucose tolerance test (OGTT), and glycated hemoglobin A1c (HbA1c). These parameters probably describe different deteriorations in glucose metabolism limiting the exchange between each other in definitions of diabetes. Objective To investigate the relationship between OGTT and HbA1c in overweight and obese children and adolescents living in Germany. Methods Study population: Overweight and obese children and adolescents (n = 4848; 2668 female) aged 7 to 17 years without known diabetes. The study population was stratified into the following subgroups: normal glucose tolerance, prediabetes, diabetes according to OGTT and/or HbA1c categories, confirmed diagnosis of diabetes. Results In the entire study group fasting plasma glucose (FPG) correlated weakly to 2-hour glucose (r = 0.26), FPG correlated weakly to HbA1c (r = 0.18), and 2-hour glucose correlated weakly to HbA1c (r = 0.17, all P