Browsing by Author "Chen, Melinda E."

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    Comparison of β-Cell Function Between Overweight/Obese Adults and Adolescents Across the Spectrum of Glycemia
    (American Diabetes Association, 2018-02) Chen, Melinda E.; Chandramouli, Aaditya G.; Considine, Robert V.; Hannon, Tamara S.; Mather, Kieren J.; Pediatrics, School of Medicine
    OBJECTIVE: Type 2 diabetes is a growing health problem among both adults and adolescents. To better understand the differences in the pathogenesis of diabetes between these groups, we examined differences in β-cell function along the spectrum of glucose tolerance. RESEARCH DESIGN AND METHODS: We evaluated 89 adults and 50 adolescents with normal glucose tolerance (NGT), dysglycemia, or type 2 diabetes. Oral glucose tolerance test results were used for C-peptide and insulin/glucose minimal modeling. Model-derived and direct measures of insulin secretion and insulin sensitivity were compared across glycemic stages and between age-groups at each stage. RESULTS: In adolescents with dysglycemia, there was marked insulin resistance (insulin sensitivity index: adolescents, median [interquartile range] 1.8 [1.1-2.4] × 10-4; adults, 5.0 [2.3-9.9]; P = 0.01). The nature of β-cell dysfunction across stages of dysglycemia differed between the groups. We observed higher levels of secretion among adolescents than adults (total insulin secretion: NGT, 143 [103-284] × 10-9/min adolescent vs. 106 [71-127], P = 0.001); adults showed stepwise impairments in static insulin secretion (NGT, 7.5 [4.0-10.3] × 10-9/min; dysglycemia, 5.0 [2.3-9.9]; type 2 diabetes, 0.7 [0.1-2.45]; P = 0.003), whereas adolescents showed diabetes-related impairment in dynamic secretion (NGT, 1,905 [1,630-3,913] × 10-9; dysglycemia, 2,703 [1,323-3,637]; type 2 diabetes, 1,189 [269-1,410]; P = 0.001). CONCLUSIONS: Adults and adolescents differ in the underlying defects leading to dysglycemia, and in the nature of β-cell dysfunction across stages of dysglycemia. These results may suggest different approaches to diabetes prevention in youths versus adults.
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    Methods for Measuring Risk for Type 2 Diabetes in Youth: the Oral Glucose Tolerance Test (OGTT)
    (Springer, 2018-08) Chen, Melinda E.; Aguirre, Rebecca S.; Hannon, Tamara S.; Pediatrics, School of Medicine
    Purpose of Review The oral glucose tolerance test (OGTT) is used both in clinical practice and research to assess glucose tolerance. In addition, the OGTT is utilized for surrogate measures of insulin sensitivity and the insulin response to enteral glucose and has been widely applied in the evaluation of β-cell dysfunction in obesity, prediabetes, and type 2 diabetes. Here we review the use of the OGTT and the OGTT-derived indices for measurement of risk markers for type 2 diabetes in youth. Recent Findings Advantages of using the OGTT for measures of diabetes risk include its accessibility and the incorporation of physiological contributions of the gut-pancreas axis in the measures of insulin response to glucose. Mathematical modeling expands the potential gains from the OGTT in physiology and clinical research. Disadvantages include individual differences in the rate of glucose absorption that modify insulin responses, imperfect control of the glycemic stimulus, and poor intraindividual reproducibility. Summary Available research suggests the OGTT provides valuable information about the development of impaired glycemic control and β-cell function in obese youth along the spectrum of glucose tolerance.