Association of Daily Home-Based Hot Water Bathing and Glycemic Control in Ambulatory Japanese Patients with Type 2 Diabetes Mellitus During the COVID-19 Pandemic: A Multicenter Cross-Sectional Study

PURPOSE: To clarify the relationship between daily hot water bathing (HWB) at home and glycemic control in middle-aged and elderly ambulatory patients with type 2 diabetes mellitus (T2DM). METHODS: We defined hemoglobin A1c (HbA1c) as the main outcome. We set 7.0% based on the mean value of the dependent variable as the cut-off point for analysis. Frequency of HWB was an explanatory variable. A two-sample t-test was used to compare between groups with continuous variables. Multiple logistic regression analysis was performed for frequency, adjusted age, sex, BMI, T2DM duration (Model 1), and other confounding factors (Model 2). Odds ratio (OR) and 95% confidence interval (95% CI) were calculated. RESULTS: Among 838 patients, there was a significant difference (p<0.001) in age between males (n=528, 62.8±8.7 years) and females (n=310, 65.0±8.1 years). In Model 1, compared with participants who used HWB more than seven times a week, those with poorly controlled HbA1c were significantly associated with low frequency of HWB: four to six times a week (OR 1.32, 95% CI 0.87–1.99) and less than three times a week (OR 1.43, 95% CI 0.98–2.10); p-value for overall trend was 0.041. In Model 2, p-value for overall trend was 0.138. CONCLUSION: A higher frequency of HWB was moderately associated with a decreased risk of poor glycemic control in middle-aged and elderly ambulatory patients with T2DM.