The proposed study uses a novel and rigorous randomized cross-over study design in youth (18-23y) with late and non-late chronotype (n=35 per group) to assess the glycemic effect of "aligning" an oral glucose tolerance test (OGTT) or first-meal of day to a subject's chronotype. Both groups will undergo 2 OGTTs (aligned and mis-aligned with chronotype) to compare glucose tolerance and insulin sensitivity within-subject (primary outcome) and between groups (Aim 1). Then, youth will also undergo two standardized meals (aligned and mis-aligned with chronotype) while wearing continuous glucose monitoring to compare post-prandial glucose excursions within-subject and between groups (Aim 2). A pilot Exploratory Aim 3 (n=12 per group) will investigate delayed melatonin patterns under dim-light as a potential pathophysiologic mechanism behind abnormal glucose tolerance in youth with late chronotype on morning OGTTs.
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AI-rewrites the medical criteria so a patient or caregiver can understand them. Always confirm with the trial site.
2-Hour Difference in Glucose
Timeframe: Day 4 and Day 11 of Aim 1 derived from OGTT
Insulin Sensitivity (by Oral Minimal Model)
Timeframe: Day 4 and Day 11 of Aim 1 derived from OGTT
2-hour Incremental Area Under the Curve (iAUC) for glucose
Timeframe: Day 1 and Day 8 of Aim 2 during post-prandial period following each standardized meal