Regional variations in diabetes prevalence and their associations with obesity and dietary habits: An ecological cross-sectional study using the National Database of Japan
Fumitake Yamaguchi, Takumi Kiyonaga, Shiori Nitta, Naoki Yoshinaga, Sayaka Akieda-Asai, Yukari Date, Hirotake SawadaBackground
Type 2 diabetes (T2D) is a major global health issue. Many Asian individuals with T2D are non-obese, suggesting that factors beyond body mass index (BMI) may be relevant.
Design and methods
This ecological cross-sectional study examined correlations between diabetes prevalence and lifestyle-related factors using age-standardized, prefecture-level data from the 2021 National Database of Health Insurance Claims and Specific Health Checkups of Japan Open Data. Variables included diabetes prevalence (glycated hemoglobin [HbA1c] ≥ 6.5%), obesity (BMI ≥ 25 kg/m 2 ), other obesity-related indicators, and self-reported dietary habits. Associations were assessed using Spearman’s rank correlation coefficients with Benjamini–Hochberg false discovery rate (FDR) correction.
Results
After FDR correction, prefecture-level diabetes prevalence was positively correlated with BMI ≥ 25 kg/m 2 , elevated waist circumference, and weight gain in both sexes, and with alanine aminotransferase in women. Among dietary variables, the proportion of individuals with impaired masticatory function was positively correlated with diabetes prevalence in both sexes, whereas daily snacking was inversely correlated only in women; breakfast skipping, late-night dinner, and fast eating were not significantly correlated in either sex. However, after adjustment for BMI ≥ 25 kg/m 2 , none of the dietary habit variables showed a significant association with diabetes prevalence in either sex.
Conclusions
Prefecture-level diabetes prevalence in Japan correlated with several obesity-related indicators and impaired masticatory function in both sexes, although impaired masticatory function was not robust to BMI adjustment. Sex-specific patterns included a positive correlation with alanine aminotransferase and an inverse correlation with daily snacking in women. These findings warrant future individual-level studies.