Association between dietary inflammatory index and obesity and dietary intake in Japanese adults with type 2...

To assess the associations between the Dietary Inflammatory Index (DII) and obesity and dietary intake in adults with type 2 diabetes (T2DM), and to compare the findings with those obtained using the modified Japanese Diet Index (mJDI).

We conducted a cross-sectional study of 1565 adults with T2DM in Japan between 2014 and 2019. Dietary intake was assessed using a validated food frequency questionnaire. The DII calculation was based on 25 nutrients. Participants were categorized into DII tertiles, and obesity was defined as BMI ≥25 kg/m². Logistic regression models were used to estimate associations between the DII and obesity with sequential adjustment for demographic, dietary, and lifestyle factors. Subgroup and sensitivity analyses were performed, and correlations between the DII and food group intakes were examined.

Participants in higher DII tertiles were younger, more often male, and had higher BMI, lower energy intake, lower protein intake per kg of body weight, and lower physical activity. Higher DII scores were associated with greater odds of obesity (OR 2.412, 95% CI 1.751-3.323; P trend <0.001). The association was consistent across sex, age, energy intake, and physical activity categories. The DII was inversely correlated with intakes of vegetables, fruits, fish/seafood, soy products, and other nutrient-dense foods. Sensitivity analyses using BMI ≥30 kg/m² showed similar but weaker associations.

Higher DII scores were associated with obesity and lower intake of nutrient-dense foods in Japanese adults with T2DM, whereas higher mJDI scores were inversely associated with obesity. Associations appeared stronger for the DII.