Background: Diabetic ketoacidosis (DKA) is the most common acute hyperglycemic complication of diabetes. According to a recent report DKA affects approximately 8 per 1000 diabetics annually. It is associated with significant morbidity and mortality, with a worldwide mortality rate of 2-10%. Objective: The aim of the work was to assessment of QTc interval prolongation among patients with DKA. Patients and Methods: This prospective observational cohort study included 100 patients who were diagnosed with DKA. The mean age of patients was 37.29±11.63 years, and 53% of them were males. All patients were subjected to detailed history taking, full clinical examination, laboratory investigations and 12-lead ECG. Results: Frequency of Prolonged QTmaxc amongst studied patients was 59%. Mean QTmaxc declined significantly after treatment to be 414.6±44.1ms compared to 482.45±63.56ms before treatment with p < 0.0001 and Frequency of prolonged QTmaxc was significantly decreased with treatment from 59% to 20%. Anion gap was significantly higher for Prolonged QTmaxc patients compared to normal QTmaxc patients p < 0.0001. While ABG (PH, HCO3) were significantly lower for Prolonged QTmaxc patients compared to normal QTmaxc patients p < 0.0001. Logistic regression revealed that anion gap was significant independent risk factor for QTmaxc prolongation while. Conclusion: patients with DKA have a potential risk of QTmaxc interval prolongation due to acidosis regardless electrolytes abnormalities, and associated with a relative risk of 1.732-fold for mortality. Carful measuring of anion gap at time of admission can be used in diagnosis and prediction of occurrence of prolonged QTmaxc with high sensitivity and specificity.