Acute Whole Body Heat Lowers Postprandial Glucose & Glycemic Variability in Healthy Female and Male College Students

Significance: Elevated postprandial glucose (PPG) is a robust predictor of cardiometabolic disease risk. While physical activity reduces PPG, the effects of whole-body heat exposure remain poorly understood. Purpose: To determine the impact of whole body heat and immediate postprandial walking in high-heat conditions on glycemic control in healthy individuals. We hypothesized that acute whole-body heat exposure (40°C) would reduce PPG and glycemic variability, and that combining heat with postprandial walking would produce additive benefits compared to heat or walking alone. Methods: Fifteen healthy non-obese adults (11 Females and 4 Males, age 20-22; BMI 23.45 ± 3.9 kg/m 2 ) wore continuous glucose monitors (CGM; Abbott Freestyle Libre Pro) measuring interstitial glucose every 15 minutes. Following an overnight fast, participants consumed a standardized breakfast meal (547 kcal:, 65% carbohydrate, 25% fat, 10% protein; glycemic index 74) and randomly completed four 90-minute trials in 25% humidity: (1) Temp-SED: seated sedentary at 20°C, (2) Temp-PA: 20 minutes walking (2.5-3mph) followed by 70 mins seated recovery at 20°C. (3) Heat-SED: seated sedentary at 40°C, and (4) Heat-PA: 20 minutes walking (2.5-3 mph) followed by 70 mins seated recovery at 40°C. PPG was quantified as glucose area under the curve (AUC). Glycemic variability was assessed using coefficient of variation (CV). Results: Mixed-model analysis revealed a temperature × physical activity interaction for postprandial glucose AUC (p=0.031), indicating that the glucose-lowering effects of heat (40°C) and physical activity are non-additive. Compared to Temp-SED, main effects showed heat reduced PPG by 12.9% and physical activity reduced PPG by 13.2%. Glucose AUC was reduced in all interventions compared to Temp-SED (10,156 ± 1,050 mg/dL/min): Heat-SED 13.4% lower (8,795±1,759 mg/dL/min), Heat-PA 12.5% lower (8,892±1,712 mg/dL/min), and Temp-PA 13.9% lower (8,747±2,172 mg/dL/min), suggesting heat and physical activity achieve similar glucose reductions through independent mechanisms. Glycemic variability (CV) exhibited a main effect of heat (p=0.016), with Heat-PA producing the greatest reduction (39.1% lower than Temp-SED). Conclusions: Acute whole-body heat exposure (40°C) reduced postprandial glucose by ~13% and improved glycemic variability in healthy normoglycemic adults. Heat and physical activity produced similar, non-additive glucose reductions, demonstrating independent mechanisms of action. These findings suggest heat therapy may serve as an accessible alternative to improve glucose control in mobility-limited individuals and the 75% of U.S. adults who do not meet physical activity guidelines. Future research is warranted to explore the efficacy of heat therapy in populations with impaired glucose tolerance and metabolic disorders, where the therapeutic benefits of heat may be even more pronounced. This abstract was presented at the American Physiology Summit 2026 and is only available in HTML format. There is no downloadable file or PDF version. The Physiology editorial board was not involved in the peer review process.