Abstract
BACKGROUND: This study investigated the association of BMI, weight change patterns, and absolute weight change with mortality in adults (≥ 50 years) with diabetes or prediabetes. METHODS: A longitudinal cohort analysis of 11,518 NHANES (2005-2018) participants assessed BMI categories, weight change patterns (stable normal weight, persistent overweight, obesity transitions, persistent obesity), and absolute weight change (loss, stable, gain). Cox models and restricted cubic splines evaluated mortality risks, adjusting for covariates. RESULTS: BMI showed a U-shaped mortality relationship, with obesity increasing all-cause (HR: 1.60, 95% CI: 1.20-2.13) and diabetes-related mortality (HR: 2.53, 95% CI: 1.35-4.75). Persistent obesity from young adulthood raised mortality risks (all-cause: +60%; diabetes-related: +153%), while later-life persistent overweight reduced risk. Weight loss (≥ 2.5 kg) increased mortality, whereas moderate gain (2.5-20 kg) was protective. Results remained robust in sensitivity analyses. CONCLUSIONS: For person with diabetes or prediabetes prevention, maintaining normal weight in early adulthood and modest weight gain with aging is beneficial. Older adults may benefit from mild overweight to lower mortality risk. Age-specific weight management strategies should guide clinical and public health recommendations. SUPPLEMENTARY INFORMATION: The online version contains supplementary material available at 10.1007/s40200-026-01896-6.