PEBC MCQ Diabetes, Thyroid, Bone & Hormones question: mg twice daily

PEBC MCQDiabetes, Thyroid, Bone & Hormones

GT, 76, takes metformin 1,000 mg twice daily. Her eGFR has fallen over a year from 52 to 26 mL/min/1.73 m2. Which of the following is the most appropriate recommendation about her metformin?

a. Change to extended-release metformin at the same dose
b. Stop metformin, which is contraindicated at this eGFR
c. Continue the same dose, as metformin protects the kidneys
d. Increase the dose to make up for reduced absorption

Show the answer and explanation

Answer: b. Stop metformin, which is contraindicated at this eGFR

The metformin product monograph and Diabetes Canada guidance contraindicate metformin when eGFR is below 30 mL/min because of the risk of lactic acidosis, with dose reduction and caution between 30 and 60. GT's eGFR of 26 means metformin should be stopped and her therapy reviewed. Metformin does not protect the kidneys, and switching formulation does not change the renal risk. Source: Metformin hydrochloride product monograph, Contraindications: eGFR < 30 mL/min (DPD, checked 2026); Diabetes Canada CPG, ch. 13 Pharmacologic glycemic management of type 2 diabetes (2018; 2024 update, Can J Diabetes 2024;48:415).

Common mistake

Continuing full-dose metformin as kidney function declines.

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