When the Transition Goes Wrong: A Rare Case of Diabetic Ketoalkalosis After Transitioning to Tirzepatide in Insulin-dependent Type 2 Diabetes

Type 2 diabetes mellitus (T2DM) often requires pharmacological management, with newer agents like glucagon-like peptide-1 (GLP-1) receptor agonists (GLP-1 RA) and dual gastric inhibitory polypeptide (GIP)/GLP-1 receptor agonists offering metabolic and cardiovascular benefits. However, transitioning from insulin therapy to these agents can lead to rare complications, such as diabetic ketoalkalosis, a metabolic disturbance marked by simultaneous ketosis and alkalosis. We report an unusual case of diabetic ketoalkalosis, a mixed acid-base disorder, in a 57-year-old female patient with insulin-dependent T2DM following a switch to Mounjaro (tirzepatide). The patient presented with nausea, vomiting, elevated anion gap, ketosis, and a slightly alkalotic venous pH. This was attributed to insulin deficiency and vomiting-induced acid loss and bicarbonate retention. Management with fluids, electrolytes, and insulin led to rapid recovery. This case highlights the need for gradual insulin tapering and close monitoring while transitioning from insulin therapy to GIP/GLP-1 receptor agonists.