Metabolic acidosis after surgery in a patient taking an SGLT2 inhibitor
A 54-year-old woman with type 2 diabetes treated with metformin and empagliflozin undergoes elective laparoscopic cholecystectomy. Two days later she develops vomiting, abdominal pain and drowsiness. Observations: heart rate 118/min, blood pressure 104/66 mmHg, respiratory rate 28/min, temperature 37.2°C. She is clinically dehydrated. Investigations: capillary glucose 11.8 mmol/L, venous pH 7.18, bicarbonate 9 mmol/L, pCO2 2.8 kPa, sodium 132 mmol/L, chloride 98 mmol/L, potassium 5.4 mmol/L, creatinine 140 micromol/L (baseline 75), capillary ketones 5.8 mmol/L.
1. What is the diagnosis, and why is the glucose only mildly elevated?
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Diagnosis: euglycaemic diabetic ketoacidosis precipitated by surgery and the SGLT2 inhibitor.
The triad is present:
- Ketonaemia 5.8 mmol/L (diagnostic threshold ≥3.0 mmol/L).
- Metabolic acidosis with pH 7.18 and bicarbonate 9 mmol/L.
- Glucose only 11.8 mmol/L - below the 13.9 mmol/L conventionally taught for DKA.
Why glucose is not high:
- Empagliflozin blocks renal sodium–glucose cotransport, so glucose is lost in the urine and the blood glucose is kept down even as insulin deficiency drives lipolysis and ketogenesis.
- The result is that the ketoacidosis can be severe while the glucose looks unimpressive - hence 'euglycaemic' DKA.
- The high anion gap confirms a ketone-driven acidosis: Na⁺ 132 − (Cl⁻ 98 + HCO3⁻ 9) = 25 mmol/L, raised.
- The surgical stress, vomiting and reduced oral intake are the precipitating factors; infection, myocardial infarction and pancreatitis must also be excluded.
The clinical judgement tested is that a normal or near-normal glucose must never be used to exclude DKA in a patient on an SGLT2 inhibitor.
2. How would you manage this patient, and what is the specific role of dextrose?
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1. Fluids - 0.9% sodium chloride resuscitation for the clinical dehydration and hypotension, then reassess. She is likely several litres down.
2. Insulin - a fixed-rate intravenous insulin infusion (0.1 units/kg/hour) is the standard. Do not delay insulin because the glucose is only mildly raised; the target of treatment is closing the ketone gap, not lowering glucose.
3. Dextrose co-infusion - this is the key point in euglycaemic DKA. Because glucose is already near normal, continuing insulin alone would cause hypoglycaemia and force the insulin to be stopped prematurely, allowing ketogenesis to continue. Add 10% dextrose once glucose falls below about 14 mmol/L so that the insulin infusion can continue until ketones clear and the acidosis resolves.
4. Potassium - K⁺ 5.4 mmol/L with acute kidney injury means potassium is likely to fall rapidly once insulin and fluids start; recheck frequently and replace when it falls below 5.5 mmol/L, with senior advice if renal function worsens.
5. Stop empagliflozin and do not restart during the admission.
6. Treat the precipitant - cultures, imaging, ECG and troponin, review of surgical site.
7. Monitor - hourly capillary ketones and glucose, 2–4 hourly venous gases and potassium, fluid balance and renal function. Resolution is defined by ketones <0.6 mmol/L, pH >7.3 and bicarbonate >15, not by glucose alone.
3. What advice would you give about restarting empagliflozin, and what general measures reduce the risk of recurrence?
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Restarting empagliflozin
- Do not restart until the patient is fully recovered, eating and drinking normally, with normal ketones and no intercurrent illness.
- Restart at a time when she is clinically stable, and document the episode clearly.
- Reassess whether the drug is essential; if she has cardiovascular or renal indications, the benefit may still justify it, but she must understand the risk.
Reducing recurrence risk
- Sick-day rules: stop the SGLT2 inhibitor during acute illness, vomiting, or reduced oral intake, and during the perioperative period.
- Perioperative planning: many centres advise stopping SGLT2 inhibitors 3–4 days before elective surgery, especially if bowel preparation or prolonged fasting is planned.
- Education: she should seek urgent assessment if she develops nausea, vomiting, abdominal pain or malaise while taking the drug, and should mention that she takes an SGLT2 inhibitor to any clinician - because her glucose may look normal.
- Avoid combining with a very low-carbohydrate diet, which independently promotes ketosis.
- Ensure the metformin dose is also reviewed given the acute kidney injury, and check renal function before restarting either drug.