Global Trends and Inequalities in Diabetes Prevalence and Treatment Coverage Among Adults Aged ≥ 45 Years, 1990–2040: Insights From the NCD-RisC Database

Aims: To assess the global burden, trends, and inequalities of diabetes prevalence and treatment coverage among adults aged ≥ 45 years from 1990 to 2040. Materials and Methods: Diabetes prevalence and treatment coverage data were obtained from the NCD-RisC database. Average annual percentage changes (AAPC) were estimated using join point regression, and a Bayesian age–period–cohort model was used to project diabetes prevalence and treatment coverage from 2023 to 2040. Cross-national health inequalities were measured using the slope index of inequality (SII) and the relative concentration index (RCI). Results: Globally, diabetes prevalence rose from 12.85% in 1990 to 23.57% in 2022 (AAPC = 1.90%), and is projected to reach 37.44% by 2040 (AAPC = 2.59%). Treatment coverage grew from 33.22% to 45.88% (AAPC = 1.02%) and is projected to surge to 51.64% by 2040 (AAPC = 0.65%). Diabetes prevalence grew fastest in middle-income countries, whereas treatment coverage improved most in higher-income countries. The SII for prevalence burden decreased from −0.25% in 1990 to −14.86% in 2022, and is projected to further decline to −18.32% by 2040. For treatment coverage, the SII increased from 24.57% in 1990 to 43.91% in 2022, with a projected rise to 54.22% by 2040. The relative inequality measured by the RCI showed a similar pattern. Conclusion: Between 1990 and 2040, diabetes prevalence is projected to increase significantly, while treatment coverage shows only limited improvement. Over the same period, the diabetes prevalence burden is increasingly concentrated in resource-limited regions, while treatment accessibility is becoming progressively more concentrated in economically developed areas.