Reproducibility of the Oral Glucose Tolerance Test in Overweight Children

• Published in: The journal of clinical endocrinology and metabolism 2008-11, Vol.93 (11), p.4231-4237
• Main Authors: Libman, I. M., Barinas-Mitchell, E., Bartucci, A., Robertson, R., Arslanian, S.
• Format: Article
• Language: English
• Subjects: Administration, Oral; Adolescent; Biological and medical sciences; Blood Glucose - metabolism; Body Mass Index; C-Peptide - blood; Child; Endocrinopathies; Fasting; Feeding. Feeding behavior; Female; Fundamental and applied biological sciences. Psychology; Glucose - administration & dosage; Glucose Intolerance - blood; Glucose Intolerance - diagnosis; Glucose Tolerance Test - standards; Humans; Insulin - blood; Insulin - metabolism; Insulin Resistance; Insulin Secretion; Male; Medical sciences; Obesity - blood; Original; Overweight - blood; Puberty; Reproducibility of Results; Vertebrates: anatomy and physiology, studies on body, several organs or systems; Vertebrates: endocrinology
• ISSN: 0021-972X; 1945-7197
• DOI: 10.1210/jc.2008-0801

Objective: We examined the reproducibility of the oral glucose tolerance test (OGTT) in overweight children and evaluated distinguishing characteristics between those with concordant vs. discordant results. Design: Sixty overweight youth (8–17 yr old) completed two OGTTs (interval between tests 1–25 d). Insulin sensitivity was assessed by the surrogate measures of fasting glucose to insulin ratio, whole-body insulin sensitivity index, and homeostasis model assessment of insulin resistance, and insulin secretion by the insulinogenic index with calculation of the glucose disposition index (GDI). Results: Of the 10 subjects with impaired glucose tolerance (IGT) during the first OGTT only three (30%) had IGT during the second OGTT. The percent positive agreement between the first and second OGTT was low for both impaired fasting glucose and IGT (22.2 and 27.3%, respectively). Fasting blood glucose had higher reproducibility, compared with the 2-h glucose. Youth with discordant OGTTs, compared with those with concordant results, were more insulin resistant (glucose/insulin 2.7 ± 1.4 vs. 4.1 ± 1.8, P = 0.006, whole-body insulin sensitivity index of 1.3 ± 0.6 vs. 2.2 ± 1.1, P = 0.003, and homeostasis model assessment of insulin resistance 10.6± 8.1 vs. 5.7 ± 2.8, P = 0.001), had a lower GDI (0.45 ± 0.58 vs. 1.02 ± 1.0, P = 0.03), and had higher low-density lipoprotein cholesterol (117.7 ± 36.6 vs. 89.9 ± 20.1, P = 0.0005) without differences in physical characteristics. Conclusions: Our results show poor reproducibility of the OGTT in obese youth, in particular for the 2-h plasma glucose. Obese youth who have discordant OGTT results are more insulin resistant with higher risk of developing type 2 diabetes mellitus, as evidenced by a lower GDI. The implications of this remain to be determined in clinical and research settings.