Predictive value of a body shape index for incident type 2 diabetes and all-cause mortality in adults: Evidence from two long-term cohort studies

Aims: To evaluate the predictive value of A Body Shape Index (ABSI) for incident type 2 diabetes mellitus (T2DM) and subsequent all-cause mortality. Methods: Data from a Japanese cohort with 13-year follow-up and the U.S. NHANES 1999–2019 T2DM cohort were analyzed. ABSI was calculated, and participants were stratified by median values. Kaplan–Meier survival curves, restricted cubic spline analyses, mediation analyses, and multivariable Cox proportional hazards models were used to assess the predictive value of ABSI. Results: Higher ABSI was significantly and linearly associated with increased risk of 13-year T2DM incidence and 20-year all-cause mortality, with HRs (95 % CIs) of 2.14 (1.73–2.65) and 1.95 (1.30–2.93). In contrast, body mass index (BMI) exhibited nonlinear associations with these outcomes. After adjusting for confounders, ABSI remained an independent predictor of both T2DM onset and mortality. Mediation analyses indicated that fatty liver (14.06 %), blood lipids (8.12 %), and blood pressure (14.59 %) may partially mediate the association between ABSI and T2DM risk, while most of the association remained directly associated with ABSI. Conclusions: ABSI is a simple and reliable predictor of T2DM onset and mortality. Routine assessment of ABSI during annual health check-ups may facilitate early identification of individuals at high risk for T2DM and adverse outcomes.