Background – Diabetes is a regional health priority in Réunion, given its high prevalence, the high incidence of risk factors, and associated complications. The Réunion Nutrition and Diabetes Control Program (PRND) was implemented during the 2020–2023 period. The objective of the study is to update the prevalence of diagnosed diabetes and describe the characteristics of people with diabetes in Réunion in 2021 in order to guide the PRND’s actions. Methods – Data from the 2021 Santé publique France DROM Health Barometer were used. In Réunion, a sample of 2,004 people aged 18 to 85, residing in the territory, were interviewed by telephone about diabetes. The analyses were weighted to account for the sampling design and response rate, ensuring they are representative of the regional population. Results – In Réunion in 2021, the prevalence of known diabetes was 13.6% (95% confidence interval, 95% CI: [11.8–15.7]) in the adult population aged 18 to 85, and among those known to be non-diabetic, 3.4% [2.4–4.6] reported having “mild diabetes.” Among those reporting diabetes, 64.3% had known about their condition for at least 5 years, 82.4% reported receiving pharmacological treatment, and among these individuals, 16.8% had already stopped their treatment at least once. Social inequalities remained very pronounced. Risk factors associated with diabetes and its complications were common: obesity (28.0%), daily smoking (20.1%), along with dietary habits that also deviated from recommendations. Conclusion – The prevalence of diagnosed diabetes remains high in Réunion. Since diabetes complications are common on the island, efforts focused on nutritional prevention must continue to reduce risk factors and the impact of social inequalities. The results of the 2021 DROM Health Barometer will help guide public policy, particularly the 2024 update of the PRND.