OBJECTIVE: To study the national incidence of admission for diabetic ketoacidosis (DKA) in Thai children and adolescents with type 1 diabetes mellitus (T1D) and characterize risk factors for DKA admission. METHODS: Admission records of children and adolescents with T1D during the years 2015-2019 were retrieved from the Thai health coverage system of all schemes. Hospitalization was categorized according to patients' age groups (<
1, 1-5, 6-12 and 13-17 years), sex and geographical regions (Bangkok, Central, Northeast, North and South). DKA admission incidence and rate were calculated and compared among subgroups. RESULTS: The annual incidences of T1D and DKA admissions per 100,000 child-years progressively increased over the study period (T1D: 12.0 to 15.0, p<
0.001 and DKA: 4.8 to 7.3, p<
0.001). About half of DKA admissions (52%) were recurrent episodes. DKA admission rate was 1.49 admissions/patient. The incidence of DKA admission was greatest in individuals aged 13-17 years (13-17 years: 10.3
6-12 years: 6.3
1-5 years: 1.7
and <
1 year: 0.6 per 100,000 child-years, p<
0.001). DKA admission incidence was greater in females than males (7.6 vs. 4.3 per 100,000 child-years, p<
0.001). Across the geographical regions, the greatest percentage of recurrent DKA (57%), rate of increased annual incidence of DKA admission (3.8 to 7.8 per 100,000 child-years), and DKA admission rate (1.64 admissions/patient) were found in the Northeast region. CONCLUSION: During the years 2015-2019, rising annual incidences of T1D and DKA admissions among Thai youth were observed. Individuals older than 6 years, being female, and resided in the Northeast region conveyed a higher risk for DKA hospitalization.