Fasting glucose versus oral glucose tolerance test for detection of glucose intolerance in obese children

Recently, the cut-off point for normal fasting glucose (FG) level, was decreased to 100 mg/dl. To determine the frequency of abnormal carbohydrate abnormalities in children with obesity and evaluate if the fasting glucose level is a useful tool for the screening of glucose intolerance (GI). Children and adolescents, referred for evaluation of obesity were evaluated with an oral glucose tolerance test (OGTT) and FG. The sensitivity of FG for detection of GI, using the 100 and 110 mg/dl cut-off point, was evaluated. We studied 186 patients (125 females) aged 12.1 (range: 5.4-19.3) years with a body mass index (BMI) of 29.9 (18.3-44.6) kg/mt2 and a BMI Z score of 2.1 (1.7-3.2). Seven patients (3.8%) had abnormalities in the carbohydrate metabolism. The sensitivity of FG for the detection of GI using the 100 and 110 mg/dl cut-off values was 42.9 and 14.3%, respectively. Receiver operating characteristic (ROC) curves showed that the optimal diagnostic level for FG corresponds to 80 mg/dl (sensitivity: 85.7% and specificity of 74.9%). An abnormal carbohydrate metabolism was detected in 3.8% of the obese children and adolescents in this sample. FG of 100 mg/dl does not detect 57.1% of the patients with glucose intolerance. These data suggest that FG is not a useful screening tool for glucose intolerance in young patients.