Weight-adjusted waist index is not superior to conventional anthropometric indices for predicting type 2 diabetes: a secondary analysis of a retrospective cohort study

Abstract Background Weight-adjusted waist index (WWI) is a new anthropometric indicator to assess adiposity. Current knowledge regarding its association with type 2 diabetes mellitus (T2DM) is limited. This present study aims to evaluate the association of WWI with the risk of T2DM in the Japanese population, and to compare its predictive ability with body mass index (BMI) and waist circumference (WC). Methods This was a secondary analysis of a retrospective cohort study involving 15,464 participants. Participants were divided into quartiles based on baseline WWI levels. Cox regression model, Kaplan–Meier curve, and smooth curve fitting were used to explore the relationship between WWI and T2DM. The discriminative ability of obesity indices in predicting T2DM was compared by the receiver operating characteristic (ROC) curve. Results After a mean follow-up of 6.05 years, 373 participants were diagnosed with T2DM. In fully adjusted models, the risk of incident T2DM was 1.96 times higher for each 1-unit increment in WWI levels (95% CI: 1.61–2.39, P < 0.001). Smooth curve fitting analysis showed a linear positive association between baseline WWI and new-onset T2DM. Subgroup analysis showed consistent results which subjects in the 4th WWI quartile had the highest risk of developing T2DM in different age, gender, and BMI groups. WWI did not exhibit better predictive ability compared with BMI and WC in the results of ROC curve. Conclusion WWI, a new metabolic index, can be used to predict new-onset T2DM in the Japanese population. However, its predictive capability was not superior to conventional anthropometric indices.