Metformin-related colonic glucose uptake; potential role for increasing glucose disposal?--A retrospective analysis of (18)F-FDG uptake in the colon on PET-CT.
OBJECTIVE
The use of metformin has been associated with diffusely increased colonic (18)F-fluorodeoxyglucose ((18)F-FDG) uptake. Interestingly, metformin use is associated with moderate weight loss. It could be hypothesized that increased colonic glucose disposal is related to this weight loss. It is unknown whether other factors influence (18)F-FDG uptake in the colon. The aim of this study was to retrospectively assess independent determinants of colonic (18)F-FDG uptake.


METHODS
We retrospectively analysed 270 (18)F-FDG PET-CTs which were made for diagnostic purposes. Colonic (18)F-FDG uptake was assessed using a 4-point scale using the liver as a reference (1; lower, 2; similar, 3; moderately higher than hepatic activity, 4; intense diffuse increased uptake). Determinants of (18)F-FDG uptake in the colon were assessed using forward logistic regression (i.e., grade 1&2 vs 3&4).


RESULTS
The patients had a mean age of 60.2±14.8 years, a BMI of 25.8±5.2kg/m(2) and 52% were female. Most patients had a grade 2 (44%) or grade 3 (39%) (18)F-FDG uptake in the colon. Diabetes mellitus type 2 was observed in 14% of the patients. In total, 5% of the patients used insulin, 12% used metformin and 5% used sulfonylurea derivatives (SU). While there seemed to be an effect of SU on (18)F-FDG uptake in the ileum [OR 3.6 (95% CI: 1.3-33.1), p=0.03], metformin was the only drug associated with (18)F-FDG uptake for both the whole colon [OR 10.0 (95% CI: 2.9-34.7), p<0.001] and all individual segments.


CONCLUSIONS
Metformin use is an independent determinant of increased colonic (18)F-FDG uptake, suggesting a potential role for increasing colonic glucose disposal.
Internal Medicine, Academic Medical Center, F4-257, P.O. Box 22660, Amsterdam 1100DD, The Netherlands. Electronic address: l.bahler@amc.uva.nl.
Lonneke
L
Bahler
Internal Medicine, Academic Medical Center, F4-257, P.O. Box 22660, Amsterdam 1100DD, The Netherlands.
Kevin
K
Stroek
Internal Medicine, Academic Medical Center, F4-257, P.O. Box 22660, Amsterdam 1100DD, The Netherlands.
Joost B
JB
Hoekstra
Nuclear Medicine, Academic Medical Center, Amsterdam, The Netherlands.
Hein J
HJ
Verberne
Internal Medicine, Academic Medical Center, F4-257, P.O. Box 22660, Amsterdam 1100DD, The Netherlands.
Frits
F
Holleman
D000368:Aged; D001692:Biological Transport; D016022:Case-Control Studies; D003106:Colon / Q000000981:diagnostic imaging / Q000187:drug effects / Q000378:metabolism*; D003924:Diabetes Mellitus, Type 2 / Q000000981:diagnostic imaging / Q000188:drug therapy / Q000378:metabolism*; D005260:Female; D019788:Fluorodeoxyglucose F18 / Q000493:pharmacokinetics*; D005947:Glucose / Q000378:metabolism*; D006801:Humans; D007004:Hypoglycemic Agents / Q000627:therapeutic use*; D008297:Male; D008687:Metformin / Q000627:therapeutic use*; D008875:Middle Aged; D000072078:Positron Emission Tomography Computed Tomography / Q000379:methods*; D019275:Radiopharmaceuticals / Q000493:pharmacokinetics; D012189:Retrospective Studies; D014018:Tissue Distribution
D007004:Hypoglycemic Agents; D019275:Radiopharmaceuticals; D019788:Fluorodeoxyglucose F18; D008687:Metformin; D005947:Glucose
(18)F-FDG; Colonic glucose disposal; Metformin