Euglycaemic Diabetic Ketoacidosis after Day-Case Surgery
Mrs D is a 52-year-old woman with type 2 diabetes (BMI 34) on empagliflozin 25 mg daily, metformin 1 g twice daily, and insulin glargine 20 units nightly. She underwent an uncomplicated laparoscopic cholecystectomy 36 hours ago and was discharged the same day. She returns with 12 hours of nausea, vomiting and increasing breathlessness. Glucose is 212 mg/dL, pH 7.18, PaCO2 22 mmHg, bicarbonate 12 mmol/L, anion gap 24 mmol/L, beta-hydroxybutyrate 5.8 mmol/L, sodium 132 mmol/L, potassium 4.9 mmol/L, creatinine 1.4 mg/dL (baseline 0.9), and urine ketones are large. She is drowsy but arousable, has deep respirations at 28/min, blood pressure 104/64 mmHg, heart rate 112, and has not eaten since the operation. She has not taken her insulin since the morning of surgery, and continued empagliflozin until the morning of admission.
1. Why is the glucose only 212 mg/dL in the presence of marked ketoacidosis, and what does this mean for diagnosis?
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Euglycaemic diabetic ketoacidosis is the key diagnosis.
- Empagliflozin causes renal glucose wasting, so plasma glucose stays lower than expected while insulin deficiency and counter-regulatory hormones drive lipolysis and ketogenesis. A glucose of 212 mg/dL therefore does not exclude DKA.
- Diagnostic triad: ketonaemia (beta-hydroxybutyrate 5.8 mmol/L), metabolic acidosis (pH 7.18, bicarbonate 12), and an elevated anion gap of 24. The glucose is below the traditional 250 mg/dL threshold, which is exactly why the condition is missed.
- Precipitants here: surgery, fasting and omission of basal insulin. Consider also sepsis, pancreatitis and metformin-associated lactic acidosis - check lactate and lipase.
- Do not attribute the presentation to dehydration or anaesthesia alone. Order a venous blood gas, ketones and electrolytes urgently in any patient on an SGLT2 inhibitor who is unwell after surgery, even if glucose is near normal.
The exam-relevant judgement is that a near-normal glucose must not override a wide anion gap with ketones.
2. Outline your initial fluid, insulin, potassium and glucose management, including how you would avoid hypoglycaemia.
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Treat the ketosis, not the glucose number.
- Fluids: 1 L of 0.9% sodium chloride in the first hour, then 250–500 mL/h, adjusting for cardiac and renal status.
- Potassium: if below 3.3 mmol/L, replace before insulin; if 3.3–5.2 mmol/L, add 20–40 mmol/L to fluids; if above 5.2 mmol/L, hold and recheck. Her potassium of 4.9 mmol/L will fall rapidly once insulin starts.
- Insulin: start a fixed-rate infusion of 0.1 units/kg/h. Add 5% dextrose when glucose falls below 200–250 mg/dL and continue insulin until the anion gap closes (≤12), bicarbonate is at least 15 mmol/L, pH is above 7.3, and ketones are cleared. Do not stop insulin because the glucose is normal - that would allow ketogenesis to continue.
- Bicarbonate only if pH is below 6.9.
- Monitoring: glucose hourly, electrolytes and anion gap every 2–4 hours. She needs admission, not discharge, despite the unremarkable glucose.
3. When should empagliflozin be restarted, and what perioperative advice would you give for future surgery?
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Restarting the drug requires a safety margin.
- Do not restart empagliflozin during this admission. Wait until she is eating and drinking normally, ketones are clear and the anion gap is closed, typically at least 48–72 hours after resolution.
- Perioperative rule for the future: stop empagliflozin 3 days before elective surgery (ertugliflozin 4 days), and restart only when oral intake is normal.
- Sick-day education: hold the drug during vomiting, poor intake or acute illness, and check capillary ketones if unwell.
- Counsel about recurrence: the risk is highest after surgery, fasting and insulin omission. She also needs a clear plan for basal insulin around procedures, because withheld insulin combined with continued SGLT2 inhibition is what produced this episode.
Document the instruction in the discharge letter; these patients are frequently readmitted when the perioperative advice is given only verbally.