Keilah Vaughan, Abigail Marmurowicz, Andre Canino, Pedro Chung, Gabe Wilner, Robert Buresh, FACSM, Cherilyn McLester, Brian Kliszczewicz, FACSM. Kennesaw State University, Kennesaw, GA.

Background: An oral glucose tolerance test (OGTT) is a standard marker used to indicate glucose regulation and metabolic health. Often, these are performed at a single time point. However it is not known if there are natural variations that may occur independent of physiological changes or adaptations. Therefore, the purpose of this project was to evaluate the variation between 2-hour OGTT.Methods: Ten (6 males, 4 females) healthy participants (ages 23±2 yrs), volunteered for this study. Participants visited the lab on three separate occasions over a 10-day span. During each visit, participants’ body composition (BF%) via bioelectrical impedance analysis (BIA), and hydration status via urine specific gravity (USG), were collected upon arrival. Immediately following, participants underwent a two-hour OGTT, consuming a 75g glucose (GLU) beverage. Plasma GLU measurements were taken via finger stick at resting (PRE), 30-minute post (30-P), 1 hour post (1h-P), and 2-hour post (2h-P) using a glucometer (Contour Next One). Area under the curve (AUC) was calculated for visit 1 (AUC1), visit 2 (AUC2) and visit 3 (AUC3). SPSS version 28.0 was used for all calculations and alpha was set to 0.05. Results: Average body mass (77 ± 15 kg), BF% (22 ± 11%), and USG (1.023 ± 0.02). A 3 (trial) by 4 (time) Repeated Measures Analysis of Variance (RM-ANOVA) was performed and found no significant trial differences (p = 0.132), but there was a significant time difference (p = <.001), and a trending time by trial interaction (p = 0.078). A one-way repeated-measures ANOVA found a significant difference among AUC measures (p = 0.027). A post hoc paired samples t-test reported that AUC1 was significantly different from AUC2 (p = 0.022), but there were no differences between AUC1 and AUC3 (p = 0.055), or between AUC2 and AUC3 (p = 0.461). Conclusions: The primary finding of this study suggest that OGTT results show deviations within a 10-day period that are independent of physiological alterations known to alter metabolic regulation (i.e., BF%). Interestingly, AUC1 was larger than AUC2, and trended larger than AUC3. Therefore, multiple OGTTs may be necessary to avoid an artificially elevated score.

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