The Effects of Hot Water Immersion on Fasting Blood Glucose and Lipids in a Prediabetic Population

Purpose: This was a proof of concept study designed to examine the effects of two weeks of hot water immersion, compared to exercise, on fasted blood glucose and lipids in a prediabetic population. It was hypothesized that hot water immersion would improve fasted blood glucose and lipids compared to baseline; although, it was uncertain how those effects would compare to exercise. Methods: Three participants volunteered to undergo a two-week intervention of either exercise plus hot water immersion (EXHWI) or exercise (EX). The exercise intervention consisted of moderate aerobic activity and strength exercises, three times per week. Subjects in the EXHWI intervention underwent a similar amount of exercise, as well as four hot water immersion sessions per week. Measures of fasted blood glucose, lipids, height, weight, BMI, and waist circumference were measured before and after the two-week intervention. Results: In the EXHWI intervention, there was a 14% decrease in fasted blood glucose, 17.6% decrease in total cholesterol, 5.1% increase in HDL, 4.6% decrease in LDL, and a 41.3% decrease in triglycerides. There was little change in weight, BMI, or waist circumference. In the EX intervention, there was a 2.8% decrease in fasted blood glucose, 13.3% decrease in total cholesterol, 6.5% decrease in HDL, 5.8% increase in LDL, and a 30.6% decrease in triglycerides. There was little change in weight, BMI, or waist circumference. Conclusion: HWI provided increased benefits when combined with an exercise program on fasted blood glucose and lipids, compared to an exercise intervention alone. HWI may provide new therapeutic or preventative approaches against metabolic diseases such as prediabetes or dyslipidemia.