Pre- and in-hospital lactate ratio as a predictor of mortality in severe diabetic ketoacidosis: a multicenter prospective cohort study

OBJECTIVE Lactate kinetics between prehospital and in-hospital measurements have been associated with prognosis in acute conditions. This study aimed to evaluate the prognostic value of the prehospital-to-hospital lactate ratio in patients with severe diabetic ketoacidosis (DKA). METHODS This was a prospective, multicenter cohort study including adults attended by emergency medical services (EMS) with a diagnosis of severe DKA or hyperosmolar hyperglycemic state. The lactate ratio was calculated by dividing the initial prehospital point-of-care lactate value by the in-hospital measurement. The optimal cutoff point was identified via locally weighted scatter plot smoother curve analysis. Survival was analyzed using Kaplan-Meier curves and Cox regression, adjusted for age, age-adjusted Charlson comorbidity index (ACCi), precipitating factor, and prehospital Glasgow Coma Scale (GCS) score. RESULTS A total of 128 patients were included (median age 71 years IQR 58.5-80, 47.7 % female). The median ACCi was 7 (IQR 5-9), and in-hospital mortality was 34.4 %. Patients were stratified by lactate ratio <1.23 or ≥1.23;baseline characteristics were broadly similar between groups, except for a higher prehospital GCS score in patients with a lactate ratio ≥1.23. Mortality was 57.3 % in the <1.23 group versus 14.5 % in the ≥1.23 group (log-rank p<0.001). A lactate ratio <1.23 was independently associated with higher mortality (HR 105.21; p<0.001), along with ACCi (p=0.023) and infectious cause (HR 3.43; p=0.014). Higher prehospital GCS was protective (HR 0.89; p=0.018). CONCLUSION Prehospital-to-hospital lactate ratio was independently associated with in-hospital mortality in severe DKA. This accessible biomarker may contribute to risk stratification and support clinical decision-making in this setting.