How organs react under fasting or glucose-insulin status: a self-controlled study using ¹⁸F-FDG total-body PET/CT

To investigate organ-specific glucose metabolism and inter-organ metabolic network alterations under fasting (FAST) and oral glucose and intravenous insulin loading (G/I) status in patients with ischemic cardiomyopathy (ICM) using total-body PET/CT.

This is a self-control, single-center prospective study conducted as part of a series investigating the imaging characteristics of ICM patients. All patients underwent two-day protocol FAST and G/I total-body ¹⁸F-FDG PET/CT scans. In the present analysis, SUV_mean were measured across 24 predefined ROIs (14 peripheral organs, 10 sub-brain regions), and compared in the FAST and G/I status. Metabolic network connectivity was assessed using mutual information-based analysis, with stratification by DM status and subgroup analyses by age and smoking status.

Thirty-three patients (17 DM, 16 non-DM) were enrolled in this study, with a mean left ventricular ejection fraction (LVEF) of 39.39%. A total of 49, 48, and 40 ROI pairs were detected under FAST in all patients, those with DM, and non-DM patients, respectively; while under G/I, 102, 48, and 55 ROI pairs were identified in turn. Non-DM patients had significant SUV_mean decreases in most peripheral organs (-28.6% to -37.6% in the liver, spleen, pancreas, and kidneys) and all sub-brain ROIs (-30.1% to -35.4%) when transition from FAST to G/I, with enhanced connectivity (48 increased and 9 reduced ROI pairs). DM patients showed attenuated SUV_mean changes (-14.6% to -10.8% in aforementioned peripheral organs; -1.0% to + 4.7% in all sub-brain ROIs) and disrupted connectivity (28 increased and 24 decreased ROI pairs), with impaired brain-peripheral interactions. In separate analyses of the DM and non-DM groups, smokers and older individuals displayed stronger inter-organ connectivity, reflecting potential influences of inflammation and disease duration on systemic metabolism.

Under FAST and G/I status, metabolic profiles of various organs and their metabolic networks were different. Compared with non-DM subgroup, DM subgroup exhibited blunted organ-level metabolic responses and attenuated changes of metabolic networks, when transitioning from FAST to G/I.

ChiCTR2400083975.