BACKGROUND: Diabetic ketoacidosis (DKA) is a potentially life-threatening metabolic disorder that can occur with manifestation of type 1 diabetes mellitus (T1D). The aim of this study was to analyze the incidence of DKA at the time of the diagnosis of T1D in childhood and adolescence, the risk factors, and regional approaches to reduce the incidence of ketoacidosis. METHODS: We investigated the proportion of patients under 18 years of age with DKA (defined as pH <7.3, severe DKA pH <7.1) at the manifestation of T1D in Germany in the period 2000-2019, based on data from the German-Austrian registry of diabetes (Diabetes-Patienten-Verlaufsdokumentation, DPV). The influence of the following factors was evaluated: year of manifestation, age, sex, family history of migration (MiH), and distance from the hospital. Moreover, data from the region with and the region without a pilot screening project from 2015 onwards were compared. RESULTS: Of the 41 189 patients with manifestation of T1D, 19.8% presented with DKA (n = 8154, slight increase [p <0.001] over the study period) and 6.1% (n = 2513) had severe DKA. Children under 6 years of age had DKA more often than adolescents (12-17 years) (21.7% versus 18.6%, OR 1.22 {95% CI: [1.14; 1.30]}). Girls had a higher rate of DKA than boys (20.5% versus 19.2%, OR 1.10 [1.03; 1.14]), and patients with MiH were more likely to have DKA than those without MiH (21.4% versus 18.2%, OR 1.40 [1.32; 1.48]). In the region with a pilot screening project, the DKA rate stayed the same, at 20.6%, while in the control region the rate was 22.7% with a decreasing tendency. CONCLUSION: The frequency of DKA at the time of diagnosis of T1D did not decrease between 2000 and 2019 and increased towards the end of the observation period. Children with MiH, children under 6, and girls were at a higher risk of DKA.