Clearance of the high intestinal (18)F-FDG uptake associated with metformin after stopping the drug

Eur J Nucl Med Mol Imaging. 2010 May;37(5):1011-7. doi: 10.1007/s00259-009-1330-7. Epub 2010 Jan 27.


Purpose: This study was done to determine whether interruption of metformin before (18)F-FDG PET/CT imaging could prevent the increased (18)F-FDG uptake in the intestine caused by this drug.

Methods: Included in the study were 41 patients with known type 2 diabetes mellitus who were referred to our department for evaluation of various neoplastic diseases. Patients underwent two (18)F-FDG PET/CT scans, the first while they were on metformin and the second after they had stopped metformin. They stopped metformin and did not take any other oral antidiabetic medication starting 3 days before the second study and their blood glucose level was regulated with insulin when necessary to keep it within the range 5.55-8.33 mmol/l. FDG uptake was graded visually according to a four-point scale and semiquantitatively by recording the maximum standardized uptake value (SUVmax) in different bowel segments. A paired-samples t-test method was used to determine whether there was a significant difference between SUVmax measurements and visual analysis scores of the metabolic activity of the bowel in the PET/CT scans before and after stopping metformin.

Results: Diffuse and intense (18)F-FDG uptake was observed in bowel segments of patients, and the activity in the colon was significantly decreased both visually and semiquantitatively in PET/CT scans performed after patients stopped metformin (p<0.05). There was a statistically significant decrease in activity in the small intestine on visual analysis (p<0.05), but semiquantitative measurements did not show a significant decrease in the SUVmax values in the duodenum or jejunum (p>0.05).

Conclusion: Metformin causes an increase in (18)F-FDG uptake in the bowel and stopping metformin before PET/CT study significantly decreased this unwanted uptake, especially in the colon, facilitating the interpretation of images obtained from the abdomen and preventing the obliteration of lesions.

Publication types

  • Clinical Trial

MeSH terms

  • Aged
  • Artifacts
  • Biological Transport / drug effects
  • Female
  • Fluorodeoxyglucose F18 / pharmacokinetics*
  • Humans
  • Intestinal Mucosa / metabolism*
  • Intestines / diagnostic imaging
  • Intestines / drug effects*
  • Male
  • Metformin / administration & dosage*
  • Metformin / pharmacology*
  • Middle Aged
  • Positron-Emission Tomography
  • Tomography, X-Ray Computed


  • Fluorodeoxyglucose F18
  • Metformin