Dose‐dependent accumulation of glucose in the intestinal wall and lumen induced by metformin as revealed by 18F‐labelled fluorodeoxyglucose positron emission tomography‐MRI

Abstract

Aims Taking advantage of the accurate registration of PET‐MRI, we recently revealed that metformin treatment is associated with enhanced accumulation of fluorodeoxyglucose (FDG) in the intestinal lumen, suggesting that metformin promotes excretion of glucose into stool. To gain insight into the clinical relevance of this phenomenon, we here investigated the relation between clinical parameters and the intestinal accumulation of FDG in metformin‐treated individuals. Materials and Methods We evaluated intestinal accumulation of [¹⁸F]FDG with both subjective (a five‐point visual scale determined by experienced radiologist) and objective analyses [measurement of the maximum standardized uptake value (SUV_max)] in 26 individuals with type 2 diabetes who were receiving metformin and underwent [¹⁸F]FDG PET‐MRI. [¹⁸F]FDG accumulation within the intestinal wall was discriminated from that in the lumen on the basis of SUV_max. Results SUV_max for the large intestine was correlated with blood glucose level (BG) and metformin dose, but not with age, BMI, HbA_1c level, or estimated glomerular filtration rate (eGFR). SUV_max for the small intestine was not correlated with any of these parameters. Visual scale analysis yielded essentially similar results. Metformin dose and eGFR were correlated with SUV_max for the wall and lumen of the large intestine, whereas BG was correlated with that for the wall. Multivariable analysis identified metformin dose as an explanatory factor for SUV_max in the wall and lumen of the large intestine after adjustment for potential confounders including BG and eGFR. Conclusions Metformin dose is an independent determinant of FDG accumulation in the wall and lumen of the large intestine in individuals treated with this drug.