Initial serum potassium (K+) in diabetic ketoacidosis (DKA) often does not reflect the true amount of total body K+ storage, and it is not a good predictor of subsequent hypokalemia. In this study, we tested the hypothesis that a deficiency of the total body K+ storage can be detected initially on surface electrocardiography (ECG).

Medical records of 350 patients with a diagnosis of DKA were reviewed. Data regarding serial basic metabolic panels, arterial blood gases, serum ketones, and total K+ replacement that patient received during admission were collected. We compared biochemical findings for patients with and without QTU corrected (QTUc) prolongation by using the t test. Patients who were taking medications known to affect QTUc or cause ST-T changes were excluded.

After exclusion criteria, 61 patients were enrolled in this study. In 38 patients (62.9%), QTUc was more than or equal to 450 milliseconds. Patients with prolonged QTc received statistically more K+ supplementation during admission (P = .014). They also had lower serum K+ level during their hospital course (P = .002) compared to patients with normal QTUc intervals. No significant difference was found between initial serum K+, calcium, glucose, anion gap, acidosis, age, or heart rate between these 2 groups.

The significant relationship between K+ depletion and the ECG changes observed in this study deserves further consideration. Our findings confirm the concept that the ECG is an easy and reliable tool for early diagnosis of hypokalemia in patients with DKA.