Objective: In the absence of a national registry for type 1 diabetes (T1D), the objective of this study was to estimate the incidence of this type of diabetes among children in France and its regional variations, using medical-administrative databases. Methods: The algorithm, designed to identify children newly diagnosed with type 1 diabetes, selected children aged 6 months to 14 years who had had at least one hospital stay of two days or more with a diagnosis of diabetes and at least one reimbursement for insulin in the following year. Children were excluded from the study if they had received reimbursement at least once for insulin or an oral antidiabetic medication prior to the start of hospitalization, or if they had another type of diabetes. Over the 2013–2015 period, specific incidence rates were calculated by sex, age group, and region. Results: Between 2013 and 2015, 6,424 children were identified as having newly diagnosed T1D. The incidence rate in France during this period was 18.0 per 100,000 person-years. The highest regional incidence rates were observed in Corsica (21.7 per 100,000 person-years), Provence-Alpes-Côte d'Azur (21.1), and Hauts-de-France (19.7). The lowest regional incidence rates were recorded in French Guiana (3.6 per 100,000 person-years), Guadeloupe (12.2), Réunion (14.2), and, in metropolitan France, in the regions of Pays de la Loire (15.8), Nouvelle-Aquitaine (16.8), and Normandy (16.9). Conclusion: Medical-administrative databases provide long-term access to information on the incidence of certain diseases. This information is essential for healthcare planning and health research. Medical-administrative databases have enabled the estimation of the incidence of T1D among all children in the French population, as well as its regional variations.