Daily brief whole-body immersion in 14 °C water temporarily decreases glucose tolerance and insulin sensitivity

Despite growing popularity, experimental evidence regarding the impact of daily cold exposure as an intervention for metabolic health has been lacking, especially with brief cold exposures. Thus, we aimed to investigate the effects of brief repeated whole-body immersion in 14 degrees C water on glucose tolerance, insulin sensitivity, and resting energy expenditure (REE) in young, nonobese adults. Twelve participants completed sixteen daily 10-min sessions involving whole-body immersion in 14 degrees C water. Changes in resting catecholamines, REE, and substrate oxidation were assessed in the overnight fasting state, while changes in glucose and insulin were assessed both in the overnight fasting state and during an oral glucose tolerance test before and 24 h after the intervention, and 1 week after the end of the intervention. The findings showed that daily brief cold water immersion (CWI) did not affect adrenaline, noradrenaline, REE, and substrate oxidation rate. However, daily CWI significantly decreased (p < 0.05) glucose tolerance as indicated by increased glucose area under the curve and insulin sensitivity as indicated by decreased Matsuda insulin sensitivity index. However, these effects were temporary and, after 1 week, the values returned to baseline. In conclusion, 16 daily sessions of brief 10-min whole-body immersion in 14 degrees C water temporarily decreased insulin sensitivity and glucose tolerance.