A Case of Euglycemic Diabetic Ketoacidosis: SGLT2 Inhibitor Complication Triggering Acute Coronary Syndrome and Cardiac Arrest Post Coronary Artery Bypass Grafting (CABG).

Sodium-glucose cotransporter-2 inhibitors (SGLT2i) are widely used in diabetes mellitus (DM) and cardiovascular disease for their glycemic and cardioprotective benefits. However, they carry an uncommon risk of euglycemic diabetic ketoacidosis (EDKA), a form of DKA with near-normal blood glucose. This complication is especially perilous in perioperative settings, and the incidence and outcomes of EDKA in cardiovascular patients have not been robustly quantified. Hence, we present a case of an elderly diabetic patient who developed EDKA on postoperative day (POD) 5 after elective coronary artery bypass grafting (CABG), which precipitated an acute coronary syndrome (ACS) and cardiac arrest. A 79-year-old male with insulin-dependent type 2 DM (on SGLT2i therapy, empagliflozin 10 mg daily) underwent uncomplicated CABG for multi-vessel coronary disease. His SGLT2i therapy was continued until the day of surgery (no preoperative washout). On POD 5, he developed high anion gap metabolic acidosis with normal glycemia (pH=7.1, pCO₂=19 mmHg, bicarbonate (HCO₃⁻)=9 mEq/L, anion gap 26.4 mEq/L). Other causes of high-anion-gap metabolic acidosis were excluded (serum lactate 1.8 mmol/L, afebrile with normal WBC, stable renal and liver function). These findings confirmed EDKA. Despite prompt insulin and fluid therapy, the patient acutely developed chest pain and hemodynamic collapse. Emergent angiography revealed a critical stenosis of the left internal mammary artery (LIMA)-to-left anterior descending (LAD) bypass graft, confirming an ACS due to metabolic stress from EDKA rather than surgical technical failure or perioperative graft occlusion. Restoration of blood flow through the LIMA-LAD graft was achieved after deploying a coronary stent across the stenosis. The patient stabilized and made a gradual recovery. This case illustrates that EDKA can impose severe metabolic stress on the heart, effectively acting as a "cardiac stress test" that triggers myocardial ischemia and arrhythmias. Current guidelines recommend discontinuing SGLT2i at least three days before major surgery to mitigate this risk. Clinicians must maintain a high index of suspicion for EDKA in postoperative patients on SGLT2i therapy after CABG surgery, as early recognition and treatment are critical to preventing catastrophic outcomes. Furthermore, the case highlights the importance of multidisciplinary management in cardiovascular patients perioperatively to mitigate the risk of EDKA and its life-threatening cardiac sequelae.