Multi-organ glucose metabolism alterations in diabetes mellitus: a total-body 18F-FDG PET/CT study

Background Diabetes mellitus (DM) is associated with systemic metabolic disturbances across multiple organs. Total-body ¹⁸ F-fluorodeoxyglucose (F-FDG) PET/CT enables simultaneous quantification of glucose metabolism in numerous organs. This study aimed to characterize multi-organ ¹⁸ F-FDG uptake patterns in type 2 DM patients compared with healthy controls and to explore associations with clinical variables including brain volume. Results Compared with controls, DM patients exhibited significantly lower SUL _mean in brain (− 15.3%, P  < 0.001), left ventricular myocardium (− 12.7%, P  < 0.001), and skull (− 9.8%, P  = 0.003), and higher SUL _mean in subcutaneous adipose tissue (+ 18.2%, P  = 0.004). Differences remained significant after multivariable adjustment. Brain volume showed strong positive correlations with SUL values across multiple organs (r = 0.44–0.63, P  < 0.01), persisting after adjustment. DM duration negatively correlated with brain and skull SUL _mean (r = − 0.33 to − 0.46, P  < 0.05). Conclusions Type 2 DM is characterized by selective glucose hypometabolism in high-energy-demand organs and compensatory adipose activation. Independent associations with brain volume and disease duration suggest potential imaging biomarkers for diabetic complications using total-body PET/CT.