The SGLT2 inhibitor sick-day rule nobody writes down

The reason it needs writing down rather than saying is that the failure mode is invisible. Euglycaemic ketoacidosis presents with malaise, nausea and breathlessness on a normal or near-normal glucose, so the meter provides false reassurance to both the patient and the first clinician who sees them. In a patient with chronic kidney disease who is also volume-depleted, the picture is easily read as pre-renal acute kidney injury and treated with fluid alone.

So: check ketones, not glucose, in an unwell patient on an SGLT2 inhibitor. Blood ketones if available, urine ketones if not.

The perioperative version needs a named owner. If the drug is to be stopped before surgery, someone has to stop it and someone has to restart it, and in most systems neither is anyone's explicit job. Write it in the pre-assessment note with a date, and write the restart criterion — eating and drinking, not a day number.

Give the rule on paper, in the patient's language, kept with the medicines.

• Stop during acute illness with poor intake, vomiting, diarrhoea, prolonged fasting, before procedures, and with alcohol excess
• Check ketones rather than glucose in any unwell patient on an SGLT2 inhibitor
• Restart on eating and drinking normally, not on a fixed number of days
• Name who stops and who restarts it around surgery, in writing, in the pre-assessment note
• Give the rule on a card in the patient's own language, kept with the medicines