Objective This study evaluated the lifestyle changes in patients with diabetes and their independent associations with glycemic and body weight control. In addition, the correlation between changes in mental health and lifestyles was evaluated.

Methods This single-center cross-sectional study included 340 patients with diabetes who periodically visited our department. Changes in dietary habits, activities of daily living, and mental health before and during approximately six months after the onset of the coronavirus disease 2019 (COVID-19) pandemic were evaluated using a questionnaire, including the International Physical Activity Questionnaire-Short Form.

Results Approximately 20%, 30%, and over 50% of patients had worsened dietary habits, decreased activities of daily living, and deteriorated mental health, respectively. A multiple regression analysis showed that irregular meal timing was significantly associated with change in HbA1c (β=0.328, p=0.001), and decreased walking time was significantly associated with changes in body weight (β=-0.245, p=0.025). The change in fear and anxiety was positively associated with changes in meal timing regularity (r=0.129, p=0.019) and carbohydrate consumption (r=0.127, p=0.021). Subsequently, the change in depressed mood was positively associated with changes in carbohydrate (r=0.142, p=0.010) and alcohol (r=0.161, p=0.037) consumption, and the change in psychological stress was positively associated with changes in carbohydrates (r=0.183, p=0.001) and snack (r=0.151, p=0.008) consumption as well as sedentary time (r=0.158, p=0.004).

Conclusions The COVID-19 pandemic has had a considerable medium-term impact on the lifestyle and mental health of patients with diabetes. Lifestyle changes were associated with glycemic and body weight control, and mental health changes were associated with lifestyle changes. These findings may provide important information on diabetes care during the pandemic.