Abstract Introduction The prevalence of type 2 diabetes mellitus in patients with obstructive sleep apnea has been estimated to be 15-30%. Studies have shown increased severity of diabetes in patients with underlying OSA independent of other confounders such as age and obesity.We aim to assess the effect of obstructive sleep apnea on patients admitted for diabetic ketoacidosis. Methods We queried the National Inpatient Sample (NIS) 2016, 2017, and 2018. We searched the NIS for adult patients hospitalized with DKA as principal diagnosis with exposure of OSA as a secondary diagnosis using ICD-10 codes. The primary outcome was inpatient mortality, while secondary outcomes were length of stay (LOS), total hospital charge, cerebral edema, cardiac arrest, acute respiratory failure (ARF), and health cost utilization defined by total hospitalization costs. Multivariable logistic and linear regression analysis was applied to estimate the clinical outcomes. STATA software was used to analyze the data. Results There were about 367,555 adult hospitalizations principally for DKA, of which 2.5% had OSA as a secondary diagnosis. Demographic characteristics based on OSA vs non-OSA cohorts with mean age of 52.3 years (CI 51.6-52.9) vs 40.4 years (CI 40.2-40.5), females (43.2% vs 49.7%), Whites (64.7% vs 57.2%), Black (25.6% vs 26.7%), and Hispanic (7.1% vs 11.6%). A total of 1,440 inpatient mortality (0.39%) occurred in hospitalizations for DKA. After adjusting for age, sex, disease severity and race, hospitalizations for DKA with OSA had similar inpatient mortality [0.59% vs 0.39%, AOR 0.81, 95% CI: 0.423 - 1.565, p=0.538], total hospital charge [$38,790 vs $30,516 P=0.185], LOS [4.19 vs 3.27 days, P=0.064], cerebral edema [0.32% vs 0.1% AOR 1.25, 95% CI: 0.437 - 3.616, p=0.671], cardiac arrest [0.54% vs 0.27% AOR 1.01, 95% CI: 0.493 - 2.105, p=0.959] compared to those without DM. However patient with OSA had an increased odds of ARF [0.55% vs 0.22% AOR 1.48, 95% CI: 1.173 - 1.867, p=0.001]. Conclusion In conclusion, patients admitted primarily for DKA with co-existing OSA had similar inpatient mortality, LOS, total hospital charges, cerebral edema, and cardiac arrest compared to those without OSA. However, the OSA group had more odds of ARF. Support (If Any) 1. Reutrakul S, Mokhlesi B. Obstructive Sleep Apnea and Diabetes: A State of the Art Review. Chest. 2017;152(5):1070-1086. doi:10.1016/j.chest.2017.05.0092. Mahmood K, Akhter N, Eldeirawi K, et al. Prevalence of type 2 diabetes in patients with obstructive sleep apnea in a multi-ethnic sample. J Clin Sleep Med. 2009;5(3):215-221.3. Morgenstern M, Wang J, Beatty N, Batemarco T, Sica AAL, Greenberg H. Obstructive sleep apnea: an unexpected cause of insulin resistance and diabetes. Endocrinol Metab Clin North Am 2014;43:187–204