Higher dietary protein/energy ratio is associated with a lower risk for obesity in older women with type 2 diabetes: Cross-sectional analysis of Japanese patients with type 2 diabetes mellitus

Objective To analyze the association between the dietary protein/energy ratio and percentages of dietary animal and plant protein and obesity in Japanese patients with type 2 diabetes. Design This was a cross-sectional study. Obesity was defined as BMI ≥25 kg/m2. Data were collected for all study participants and stratified according to age and sex. Diet was assessed via a food frequency questionnaire. Setting 26 clinics participating in the Japan Diabetes Clinical Data Management Study Group (JDDM) from December 2014 to December 2019. Participants 1567 Japanese out patients with type 2 diabetes (63.1% men; mean age 62.3 ± 11.6 years). Results In all participants, multivariate analysis with adjustment by major confounders showed a significant inverse association in those in the highest quartile of the protein/energy ratio (mean 17.7%) with obesity (OR = 0.588, 95% CI = 0.435-0.794; p trend = 00.007), but after the addition of vegetable intake it became non-significant. In the age- and sex-stratified analysis, a high protein/energy ratio (mean 15.6%) was inversely associated with obesity in older women only (OR = 0.280, 95% CI = 0.123-0.638), which remained significant after adjustment of individual food groups correlated with protein. No association between percentages of dietary animal or plant protein and obesity was found. Conclusions In older women only, a higher dietary protein/energy ratio was associated with lower obesity after adjustment by confounders and individual food groups correlated with protein intake. Future longitudinal research that includes data on food groups as well as age- and sex-stratification of participants is recommended to further clarify this relationship.