title: Impact of medication discontinuation on increased intestinal FDG accumulation in diabetic patients treated with metformin.
abstract: OBJECTIVE
  We evaluated the impact of stopping medication for 2 days on reductions in the high intestinal FDG uptake induced by metformin.
  
  
  METHODS
  One hundred thirty-eight diabetic patients were divided into two groups: one in which the antihyperglycemic drug regimen included metformin (group A; n = 107) and one in which the regimen did not include metformin (group B; n = 31). Fifty-two patients without diabetes mellitus served as the control group (group C). Group A was divided into two subgroups: 77 patients (group A1) were taking metformin at the time of FDG PET/CT scans, whereas the remaining 30 patients (group A2) were asked to stop taking metformin for 2 days before PET/CT scans. In addition, 10 diabetic patients underwent two consecutive PET/CT scans before and after the discontinuation of metformin. The intestinal FDG uptake and blood glucose levels were compared among the four groups, as well as before and after the discontinuation of metformin.
  
  
  RESULTS
  The high intestinal FDG uptake in group A1 was significantly reduced after the discontinuation of metformin (p < 0.001 vs group A2); thus, there were no significant differences among group A2, group B, and group C (p = 0.581-0.872). There were also no statistically significant differences in the blood glucose levels among the three groups of diabetic patients (p > 0.9). In 10 patients who underwent serial PET/CT scans, mean intestinal FDG uptake decreased by 64% without significant changes in the blood glucose level. Hidden colorectal malignancies were revealed in two patients after the discontinuation of medication.
  
  
  CONCLUSIONS
  The discontinuation of metformin for 2 days is feasible for reducing the high intestinal FDG uptake induced by metformin.
authors.affiliation: Department of Nuclear Medicine, Chonnam National University Medical School and Hospital, 8 Hakdong, Dongku, Gwangju 501-757, Republic of Korea.
authors.forename: Jong-Ryool
authors.initials: JR
authors.lastname: Oh
authors.forename: Ho-Chun
authors.initials: HC
authors.lastname: Song
authors.forename: Ari
authors.initials: A
authors.lastname: Chong
authors.forename: Jung-Min
authors.initials: JM
authors.lastname: Ha
authors.forename: Shin-Young
authors.initials: SY
authors.lastname: Jeong
authors.forename: Jung-Joon
authors.initials: JJ
authors.lastname: Min
authors.forename: Hee-Seung
authors.initials: HS
authors.lastname: Bom
mesh_terms: D000704:Analysis of Variance; D001692:Biological Transport / Q000187:drug effects; D016022:Case-Control Studies; D003924:Diabetes Mellitus, Type 2 / Q000188:drug therapy*; D005260:Female; D019788:Fluorodeoxyglucose F18 / Q000493:pharmacokinetics*; D006801:Humans; D007004:Hypoglycemic Agents / Q000008:administration & dosage*; D007422:Intestines / Q000000981:diagnostic imaging* / Q000187:drug effects; D008297:Male; D008687:Metformin / Q000008:administration & dosage*; D008875:Middle Aged; D049268:Positron-Emission Tomography; D011446:Prospective Studies; D019275:Radiopharmaceuticals / Q000493:pharmacokinetics*; D018709:Statistics, Nonparametric; D014057:Tomography, X-Ray Computed
chemical_list: D007004:Hypoglycemic Agents; D019275:Radiopharmaceuticals; D019788:Fluorodeoxyglucose F18; D008687:Metformin