Risk of Type 2 Diabetes According to Body Mass Index, Television Viewing Time, and Their Combination in the Japanese Population: Findings From the Japan Collaborative Cohort Study

Objective This study aimed to investigate the associations of body mass index (BMI), television viewing time, and their combination with the risk of Type 2 diabetes among Japanese individuals using data from a large Japanese prospective cohort study. Methods This prospective cohort study included 23,604 Japanese participants (9,284 males and 14,320 females) aged 40–79 years. Baseline data were collected between 1988 and 1990 using a self‐administered questionnaire. In the 5‐year follow‐up survey, Type 2 diabetes was identified through self‐reported physician diagnoses. We used a logistic regression model to analyze the associations of BMI and television viewing time, and their combination with the risk of Type 2 diabetes. Results During the 5‐year follow‐up, 5.9% of participants developed incident Type 2 diabetes. BMI and prolonged TV viewing time were independently associated with an increased risk of developing Type 2 diabetes. Individuals with obesity (BMI ≥ 30 kg/m 2 ) who viewed TV for ≥ 7 h had a twentyfold increase in diabetes risk (odds ratio: 21.42, 95% confidence interval: 7.23–63.49) compared with those with normal BMI (18.5–24.9 kg/m 2 ) who viewed TV for ≤ 3 h, indicating a significant interaction. Conclusions Our study underscores the importance of addressing obesity and sedentary behavior to mitigate Type 2 diabetes risk.