Felix Teufel, Katherine Orgutsova, Irini Genitsaridi, Rodrigo M. Carrillo-Larco, Jithin Sam Varghese, Maja Marcus, Julian W. Sacre, Seyedeh Forough Sajjadi, Faraja S Chiwanga, J. Manne-Goehler, J. Seiglie, D. Flood, Jessica L. Harding, Paraskevi Salpea, Agus Salim, Edward J. Boyko, Dianna J. Magliano, MK Showkath Ali
OBJECTIVE: Undiagnosed diabetes leads to delayed treatment and increased risk of complications, exacerbating global disease burdens. In this study, we estimated the prevalence and absolute numbers of individuals with undiagnosed diabetes globally and across regions and quantified gaps in national diabetes detection efforts. RESEARCH DESIGN AND METHODS: We systematically compiled estimates of biomarker-based diabetes prevalence and self-reported diabetes diagnosis using 2003-2024 data from all eligible population-based studies and gray literature. We calculated proportions of individuals with undiagnosed diabetes and case numbers among adults aged 20-79 years. For countries without data, we extrapolated estimates using available data within the same geographic region and country income group. Country-level estimates were benchmarked against the World Health Organization 80% diagnosis target. RESULTS: We identified 193 data sources on undiagnosed diabetes from 109 countries. Across all 215 countries/territories, 42.8% of individuals with diabetes were undiagnosed in 2024, equating to 251.7 million (95% uncertainty interval [UI] 250.4-253.0 million) adults. Proportions undiagnosed ranged from 16.2% in Colombia to 90.4% in Burkina Faso and 29.1% in North America and the Caribbean to 72.6% in Africa. A larger proportion of individuals were undiagnosed in low-income (58.7%) compared with high-income countries (28.9%). Middle-income countries accounted for 206.0 million (95% UI 202.3-209.7 million) adults with undiagnosed diabetes (81.8% of all individuals), including 127.1 million (95% UI 121.2-133.0 million [or 50.5%]) adults in China, India, and Indonesia alone. Less than 5% of all countries attained diabetes diagnosis levels ≥80%. CONCLUSIONS: Substantial global variability in undiagnosed diabetes indicates opportunities to close existing care gaps, likely requiring context-specific solutions and investments.