Abstract: Objective To investigate the risk factors of hyperlactatemia in children with diabetic ketoacidosis. Methods A total of 101 children with diabetic ketoacidosis, aged 2-15 years, who were admitted to the Affiliateel Huai'an First People's Hospital of Nanjing Medical University from January 2015 to December 2020 were enrolled and their clinical data were retrospectively analyzed. According to the severity of disease, they were divided into three groups: a mild group, a moderate group and a severe group. According to serum lactic acid level, they were divided into a high lactic acid group (≥2.0 mmol/L) and a non-high lactic acid group (<2.0 mmol/L). Then, their general information was collected, including sex, age, new-onset diabetes, systolic blood pressure, and diastolic blood pressure. Furthermore, blood glucose, blood urea nitrogen, creatinine, glycosylated hemoglobin, blood pH value, HCO^-₃, serum sodium, serum potassium, lactic acid, total cholesterol, triglyceride, thyroid function and other clinical biochemical indicators after admission were detected. The differences in clinical biochemical indexes were compared between the two lactic acid groups. Correlation analysis was conducted to explore the relationship between serum lactic acid level and clinical biochemical indexes, DKA severity, DKA correction time, and average hospitalization costs. The risk factors for hyperlactatemia in children with DKA were examined by regression analysis. Results Among the 101 DKA children, 42 showed elevated serum lactic acid, with an average level of 3.12 mmol/L. The high lactic acid group presented higher age and blood glucose after admission, and lower pH values and HCO^-₃ levels than the non-high lactic acid group. The incidence of new-onset diabetes in the high lactic acid group was lower than that in the non-high lactic acid group. Serum lactic acid level in DKA patients were positively correlated with DKA severity, age, blood glucose after admission, and new-onset diabetes, but negatively correlated with pH value and HCO^-₃, without relationship with DKA correction time and hospitalization costs. Logistic regression analysis showed that hyperglycemia after admission and new-onset diabetes were the independent risk factors for elevated serum lactic acid levels in DKA patients. Conclusions Hyperglycemia after admission and new-onset diabetes are the independent risk factors for hyperlactatemia in children with DKA. This study provides important theoretical basis for the prevention of hyperlactatemia in children with DKA.