Burden of type 2 diabetes in working-age adults (20–54 years): a GBD 2021 analysis projecting trends to 2035 and exploring the potential benefits of physical activity

Background: Type 2 diabetes (T2D) has risen sharply across all age groups and regions, with growing disability and premature mortality. Evidence on regional disparities and modifiable drivers, particularly low physical activity, is needed to guide targeted prevention. Methods: Using Global Burden of Disease (GBD) 2021 data spanning 1990 to 2021, we analyzed the incidence, mortality, and disability-adjusted life years (DALYs) of T2D among adults aged 20-54 years. We estimated average and annual percentage changes (EAPCs) along with their 95% uncertainty intervals (UIs), compared the burdens across Socio-demographic Index (SDI) categories and geographic regions, quantified the proportion of burden attributable to low physical activity, and projected future trends through 2035. Results: From 1990 to 2021, global T2D cases in working-age adults increased by 216% to 13.69 million (95% UI: 12.15-15.47), while mortality rose by 112% to 176,562 deaths (95% UI: 163,156-189,590). DALYs increased by 194% to 22.17 million (95% UI: 17.43-27.93). The burden was higher among men and increased with age. Significant disparities were observed: high-SDI regions had the highest incidence rates, while lower-middle-SDI regions had the highest mortality rates. Oceania, the Caribbean, and Central Latin America showed the highest regional rates. In 2021, low physical activity accounted for 863,921 DALYs (95% UI: 377,518-1,366,461) in this age group. Projections suggest continued increases in T2D burden through 2035. Interpretation: The T2D burden in working-age adults has more than doubled since 1990, with large inequalities across regions and SDI levels. Physical inactivity is a significant modifiable risk factor. Urgent region-specific strategies integrating physical activity promotion, healthier food environments, and improved primary care are needed to reduce future burden and inequities.