This study aims to identify the effect of atrial fibrillation on mortality in patients admitted with DKA. We used the National Inpatient Sample Database for the year 2018 and 2019 to identify patients hospitalized with DKA. Association of atrial fibrillation was confirmed using the International Classification of Disease, Tenth Edition (ICD 10 CM). We performed a retrospective analysis on this database using STATA (Stata Corp, College Station, TX). The primary outcome was mortality in DKA. Length of stay (LOS) and total hospitalization charge were the secondary outcomes. There was a total of 447,570 DKA patients out of which 12,770 had associated atrial fibrillation in the year 2018e2019. The mean age of patients with DKA and AFIB was 62 years. Approximately 46% of patients were female in DKA with AFIB group. The multivariate logistic analysis showed increased mortality in patients with DKA and AFIB (OR = 1.4, p = 0.048). Predictors of increased mortality were older age and teaching status of hospitals in metropolitan areas (OR = 1.0, p < 0.001 and OR = 1.4, p = 0.031 respectively). LOS was lower in patients with DKA and AFIB compared to DKA alone (3.1 day and 5.2 days respectively, OR = 0.82, p < 0.001). Total hospitalization charge was higher for patient in DKA with AFIB (USD 53,576 and USD 32,533 respectively, coefficient = 10,513, p < 0.001). Patients hospitalized with DKA and AFIB had higher mortality compared to patients without AFIB, while they showed lower LOS but increased hospitalization cost. Further research in this direction would be helpful to better understand this association.