Impact of Hypophosphatemia and Hypomagnesaemia on Diabetic Ketoacidosis patient's Outcome in Medical Intensive Care Unit Background: Diabetic ketoacidosis (DKA) is a life-threatening condition of biochemical derangements comprising hyperglycemia, acidosis, and ketonemia. The study aimed to explore the prognostic impact of phosphate (Po4) and magnesium (Mg) levels on DKA-associated morbidity and mortality. Methods: Sixty-eight patients with DKA were admitted to the intensive care unit (ICU) in the Internal medicine Department in Zagazig University Hospital over the period of 6 months were evaluated serially for Po4 and Mg levels among other routine investigation. The patients were followed for the inhospital clinical outcome. Results: hyponatremia, HbA1c, random blood sugar (RBS), creatinine, urea, ICU stay, low pH, and hypophosphatemia showed a strong correlation with a mortality rate (P<0.001), while hypomagnesemia was insignificant. A positive correlation was noticed between Po4 and sodium (Na) level (P=0.004), whereas a negative correlation with RBS (P=0.001), HbA1c (P=0.001), creatinine (P=0.001), urea (P=0.001), and ICU stay duration (P=0.008). Hypophosphatemia had a 13-fold higher relative risk for mortality in DKA. Conclusion: We concluded that hypophosphatemia was an independent predictor of the DKA-associated mortality rate, and serial Po4 measurement should be considered in DKA treatment protocols.