Screening for dysglycemia in overweight youth presenting for weight management

OBJECTIVE

To examine the performance of current screening recommendations for detecting dysglycemia in children and adolescents with obesity.

RESEARCH DESIGN AND METHODS

In a cross-sectional study, an oral glucose tolerance test and demographic (age, sex, family history of diabetes, and ethnicity), clinical (BMI z score, waist circumference, and pubertal stage), and laboratory variables used in current pediatric screening criteria for type 2 diabetes mellitus were measured in 259 overweight or obese youth aged 5–17 years. Glycemic status was based on American Diabetes Association (ADA) thresholds. The performance (sensitivity and specificity) of current screening criteria and newly developed models to identify isolated IGT were compared.

RESULTS

Dysglycemia was present in 20.8% of the cohort. Of the 54 participants with dysglycemia, 68% had a normal fasting glucose and were identified with the 2-h glucose test. Current ADA criteria had low sensitivity (41.7% 95% CI 25.6–57.8]) and moderate specificity (69.5% 63.5–75.6]) to identify IGT. In receiver operating characteristic (ROC) analysis, the addition of hemoglobin A_1c (HbA_1c) or FPG did not improve the ROC area under the curve (AUC) (HbA_1c: 0.64 vs. 0.63; P = 0.54; HbA_1c + FPG: 0.66; P = 0.42), but adding triglyceride level did (AUC 0.72 vs. 0.63; P = 0.03). A simple model with fasting triglyceride level >1.17 mmol/L improved AUC compared with ADA screening criteria (0.68 vs. 0.57; P = 0.04).

CONCLUSIONS

The prevalence of IGT is high among obese children and youth. Current screening criteria have low sensitivity to detect isolated IGT. Although adding nonfasting laboratory values to history and physical measures does not improve diagnostic accuracy, adding fasting lipid profile improves predictive value.Obesity-related metabolic abnormalities are common in children and adolescents with obesity. Impaired glucose tolerance (IGT), an important predictor of progression to type 2 diabetes mellitus (T2DM) in youth (1), is identified in overweight and obese children, although the prevalence varies considerably with the population studied. Although 20–25% of overweight youth presenting to a weight management program in the northeastern U.S. were diagnosed with IGT (2), clinical cohorts in other countries have had much lower prevalence (5–17%) (3–5). In adults, IGT is a strong predictor for progression to T2DM (6) and increased risk of cardiovascular disease, independent of the development of T2DM (7). Randomized controlled trials of lifestyle or medication interventions in adults with IGT have demonstrated that T2DM can be prevented (8,9). Because the detection of IGT requires the performance of a cumbersome oral glucose tolerance test (OGTT), strategies to minimize the number of people requiring such a test have been studied in adults (10,11). Few such studies have been done in children and adolescents.Current American Diabetes Association (ADA) guidelines recommend screening high-risk populations with a fasting plasma glucose (FPG) test (12,13), although they acknowledge that the best screening test and the population of obese children and youth that should be screened require further investigation (14). The majority of children with IGT have a normal fasting glucose (2), suggesting that FPG alone may be inadequate to identify prediabetes and that an OGTT be considered for screening in at-risk youth. Because the OGTT is costly, it should be performed on those at highest risk only, but little evidence evaluating the risk prediction properties of current screening criteria is available.This study examines the clinical usefulness of current screening recommendations in identifying dysglycemia (T2DM, impaired fasting glucose IFG], or IGT) in a cohort of 259 children and youth (aged 5–17 years) presenting to a weight management program and identifies a potential new screening tool for identification of obese youth with dysglycemia.