The assocations of specific dietary factors with measures of glycemia in obese adolescents
Prevalence rates of prediabetes and type 2 diabetes (T2D) are increasing in adolescents. Being overweight is a risk factor for T2D, however weight loss and maintenance have been proven difficult to attain in youth. Dietary behaviors are modifiable and may be targeted to improve glycemia independent of weight loss. However, key dietary factors that are responsible for reducing risk of developing T2D remains understudied in adolescents. Our first investigation was a retrospective, cross-sectional study conducted to evaluate associations between dietary factors and measures of glycemia in overweight adolescents who underwent 2-hour oral glucose tolerance tests (OGTT) in a clinical setting. Dietary habits were captured using a modified version of the Bright Futures Adolescent Supplemental Questionnaire, which is a common clinical assessment tool that includes nutrition-specific questions. Characteristics of this population (N=146) were, 13.7 ± 0.2 (standard error mean) years of age and body mass index (BMI) 33.9 kg/m2 (20.6 – 65.3 kg/m2, 95% confidence interval). Forty percent of adolescents were diagnosed with prediabetes. We found relationships between dietary behaviors and glycemic measures. A high daily intake of dessert food items was associated with higher concentrations of glucose at 2 hours (β = 0.23; P = 0.004) and a high intake of packaged snack foods was associated with higher blood concentrations of hemoglobin A1c (β = 0.04; P = 0.04). Relationships between diet and glycemic measures were independent of adiposity. Our findings suggest that snack foods that are presumably consumed by adolescents may have detrimental effects on glucose homeostasis and diabetes risk. However, more detailed dietary information is needed to determine the specific nutrients within the grouping of dessert items and packaged snack foods (e.g. solid fat, added sugar) that influence glycemia in obese adolescents. The second investigation used cross-sectional, pilot data, collected at baseline, which was obtained from an ongoing, randomized controlled intervention to prevent T2D in obese youth, to determine the associations between specific dietary macronutrients with measures of glucose and insulin dynamics. Daily dietary intake was assessed prospectively using mobile phone technology to create electronic food records for four days. Measures of glycemia as well as detailed measures of insulin action (whole body insulin sensitivity, insulin secretion and beta-cell function) were assessed using an OGTT. Fifteen obese youth were assessed: their age was 13.1 years ± 2.5 (standard deviation) and their BMI was 34.9 kg/m2 ±1.2. Approximately half (47%) of the study participants were diagnosed with prediabetes. Demographic measures were similar between youth with prediabetes and youth with normal glycemia. Youth with prediabetes tended to consume more saturated fat (27.4 vs 22.5 g, P=0.1) than youth with normal glycemia. We found associations among dietary macronutrients, measures of glycemia and insulin action. Total dietary fat intake was associated with concentrations of glucose at 2 hours (β=1.3, P= 0.006), insulin sensitivity (β=-1.5, P= 0.002), and beta-cell function (β=-1.6, P= 0.0009); and total fiber was negatively associated with concentrations of glycosylated hemoglobin (β=-0.57, P= 0.04). Adiposity was not controlled for in this analysis, however there was no difference in anthropometric measures between youth with prediabetes and youth with normal glycemia. Although our findings are preliminary, they demonstrate feasibility of the hypothesis that dietary variables are related to glucose and insulin action in obese youth. Collectively, our observations suggest that in overweight adolescents, dietary intake is uniquely associated with prevalence of glycemia and potential risk of developing T2D. In conclusion, our findings support the concept of modifying dietary habits by reducing dessert items, packaged snack foods, or total fat, or by increasing total fiber in interventions designed to prevent T2D in obese adolescents
Gletsu-Miller, Purdue University.
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