Fasting Plasma Glucose (FPG) and the Risk of Impaired Glucose Tolerance in Obese Children and Adolescents

Abstract

A timely diagnosis of impaired glucose tolerance (IGT) is desirable in obesity. The oral glucose tolerance test (OGTT), the gold standard to diagnose this condition, may not be realistically performed in all patients due to discomfort, labor, and cost. The aim of this study was to assess whether one or more biochemical indexes measured in fasting conditions could be used to identify obese children at risk of IGT. A cohort of 563 white obese children and adolescents (M/F: 315/248; aged 4–17 years) was recruited and underwent anthropometric evaluation and OGTT. Anthropometric parameters, fasting plasma glucose (FPG), fasting serum insulin (FSI), and homeostasis model assessment of insulin resistance (HOMAIR) were tested in pursuit of a possible threshold to be used as a predictor of IGT. Thirty‐seven children (6.9%) had IGT and one child (0.1%) had type 2 diabetes (T2D). FPG, FSI, and HOMAIR were all significantly higher in children with IGT than in children without IGT. Receiver‐operating characteristic (ROC) curve analyses run for gender and puberty‐adjusted FPG, FSI, and HOMAIR were all significant: area under the curve (95% confidence interval) equaled 0.68 (0.59–0.76), 0.66 (0.56–0.76), and 0.68 (0.59–0.78), respectively. The three parameters did not show significantly different sensitivity/specificity in the pooled population or in the gender/puberty subgroups. Thresholds varied among gender/puberty subgroups for FSI and HOMAIR, but not for FPG, which showed a fixed threshold of 86 mg/dl. A gender/puberty independent cutoff of FPG may be considered a screening tool to narrow clinical indication to OGTT in obese white children and adolescents.

Prevalence of Prediabetes and Type 2 Diabetes in Children With Nonalcoholic Fatty Liver Disease

“…Because type 2 diabetes occurs predominantly among the 20% of youth with obesity, an estimated diabetes rate among obese youth of 0.42 per 200 remains well below 1%, much less than 6.5% prevalence observed in our cohort of children with NAFLD. Although the NASH CRN enrollment does not aim to represent the population, the findings suggest that youth with NAFLD have substantially higher risk of type 2 diabetes than obese youth in general 22, 23 . It is possible we over-diagnosed type 2 diabetes based on using single measurements of fasting glucose and HbA1C to classify glucose status in this study.…”

Insulin resistance in type 2 diabetic youth

“…It remains unclear whether the same cutoffs should apply to youth, and whether mild elevations during the increased insulin resistance of puberty will persist [41 ▪ ,52,53 ▪ ,54,55 ▪ ]. Both fasting and OGTT-based measures can be problematic for early diagnosis [17 ▪▪ ,26,56 ▪ ,57 ▪ ,58,59], HbA1c and OGTT values are poorly correlated [41 ▪ ], repeated OGTT’s have poor reproducibility in youth [60] and HbA1 can vary substantially depending on method, making diagnosis of prediabetes and early T2DM difficult. One recent proposal was to conduct OGTTs in children with a HbA1c more than 5.5% [61], whereas others recently proposed an algorithm including glucose, triglycerides and BMI; HbA1c did not add to the predictive value of this method [62 ▪▪ ].…”

Predictors of Metabolic Risk in Childhood Obesity

“…The American Diabetes Association's criteria for selecting children to test for T2DM and criteria specifically designed for screening obese children for IGT in European populations, such as a clinical score issued from a German cohort or the fasting glucose cut-off of 86 mg/dl issued from an Italian cohort [56,57], have recently shown sub-optimal accuracy in identifying IGT when tested in different populations [58]. Also, a clinical score based on data from a multi-ethnic American cohort showed only moderate accuracy [39].…”