Abstract Introduction Diabetic ketoacidosis is a common diabetic emergency requiring admission to the intensive care unit , patient with DKA usually present with profound dehydration secondary to osmotic diuresis and one of the major hallmark of treatment is adequate hydration with normal saline, the aim of this study is to establish the possible outcomes that might occur if a patient who has a background history of Heart failure with preserved ejection fraction with DKA, there are studies establishing a relationship between DKA and heart failure with reduced ejection fraction but none has been done to establish possible outcomes in this patient population and this study aims to bridge that gap. Methods We analyzed the National Inpatient Sample (NIS) database from 2018 to 2020. The NIS was searched for hospitalization of adult patients with DKA with and without heart failure with preserved ejection fraction . the outcomes analyzed were in-hospital mortality, Cardiogenic shock, septic shock, acute kidney injury, total hospital charge and length of stay. Multivariate logistic and linear regression analysis were used accordingly to adjust for confounders. Results A total of 261,410 patients were admitted for DKA, 7.8% (20,280) had HFPEF and 92.2% (241,130) were without HFPEF, among those with HFPEF 50.9% were female and 49.1% were male while among those without HFPEF 44.5% were female and 55.5% were male, compared with those without HFPEF, patients with HFPEF had a statistically significant increase in in-hospital mortality (1.92% vs 0.65%, p<0.007,OR-1.46, 95% CI 1.10-1.93) Length of stay (5.3 vs 3.6, p value<0.0001, IRR = 1.12, 95% CI 1.08-1.15), septic shock (3.08% vs 1.49%, p value<0.023, OR = 1.27, 95% CI 1.03-1.56), cardiogenic shock (0.9% vs 0.19%, p value<0.0001, OR = 4.6, 95% CI 2.77-7.66) and Total hospital charge ($55583.7 vs $38632.24, p value<0.0001, IRR = 1.15, 95% CI 1.1-1.19), there was no statistically significant difference in acute kidney injury(53.21% vs 44.27% p value 0.09, OR 1.1, 95% CI 0.89-1.23) Conclusion This study has been able to establish a significant increase in in-hospital mortality, Length of stay, septic shock, cardiogenic shock and total hospital charge in patients with DKA and HFPEF and no difference in the rate of AKI, patients with HFEPF should be considered as a special population when managing DKA and fluid management in this patient population will need further studies.