Management of Metformin Before Colonoscopy

Rationale for Discontinuation

Metformin should be temporarily discontinued before procedures including imaging studies using iodinated contrast, during hospitalizations, and when acute illness may compromise renal or liver function, as recommended by the American Diabetes Association 2

The American Journal of Kidney Diseases recommends that patients continue taking metformin as prescribed until the day before colonoscopy, and then stop metformin on the morning of colonoscopy, with a strength of evidence based on clinical guidelines 1
For patients undergoing colonoscopy with a split-dose bowel preparation regimen, the Gastroenterology society recommends beginning the second portion of bowel preparation 4-6 hours before colonoscopy and completing the preparation at least 2 hours before the procedure, with a moderate level of evidence 3
The American Journal of Kidney Diseases recommends checking kidney function before restarting metformin, especially in high-risk patients, with a high strength of evidence 1

The European Journal of Nuclear Medicine and Molecular Imaging recommends monitoring blood glucose levels more frequently during the period when metformin is discontinued for patients with diabetes, with a low to moderate level of evidence 4