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Metformin sick day guidance — GPhC CRA MCQ

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HardEndocrine TherapeuticsMetformin sick day guidanceGPhC CRA

A 66-year-old woman taking metformin 1g twice daily has vomiting and diarrhoea after gastroenteritis. She has CKD stage 3a and her home blood glucose is 8.2mmol/L. She is drinking small amounts but has passed little urine today. What would you advise the patient?

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Correct answer: B — temporarily withhold metformin and seek urgent advice if dehydration persists

Metformin should be temporarily withheld during significant dehydration because acute kidney injury increases the risk of lactic acidosis. Reduced urine output is a concerning marker and supports urgent clinical advice if hydration cannot be maintained. Continuing or doubling metformin would increase risk. A community pharmacist should not switch to gliclazide without prescriber assessment.

Reference: BNF; NICE CKS: Diabetes type 2