Pancreatic fat deposition as a mediator of adrenal gland volume and type 2 diabetes: evidence from MRI

To assess the role of body composition mediating the association between MRI-quantified adrenal gland volume (AGV) and type 2 diabetes mellitus (T2DM) and to clarify the underlying mechanisms involved. This retrospective study analyzed 239 hospitalized patients (54 T2DM, 185 non-T2DM) with abdominal MRI. AGV was manually segmented on T1-weighted images. Body composition parameters, including subcutaneous adipose tissue (SAT) area and fat fraction (FF), visceral adipose tissue (VAT) area and FF, hepatic FF (HFF), pancreatic FF (PFF), and abdominal muscle (AM) area and FF, were quantified using MRI fat fraction mapping. After adjusting for age, sex, hypertension, and BMI, mediation analysis showed that PFF partially mediated the association between AGV and T2DM (OR = 1.036, 95% CI: 1.009–1.101), accounting for 8.7% of the total effect. Multivariate analysis identified both AGV (OR: 1.475, 95% CI: 1.235–1.762) and PFF (OR: 1.069, 95% CI: 1.023–1.116) as independent factors associated with T2DM. ROC analysis showed AUCs of 0.792 for AGV and 0.803 for PFF in differentiating T2DM. The combined AGV + PFF model achieved an AUC of 0.836 (95% CI: 0.779–0.894). MRI-quantified AGV and PFF demonstrate potential as biomarkers for T2DM. Pancreatic fat deposition partially mediates the link between adrenal enlargement and T2DM, suggesting a novel pathway involving HPA axis dysregulation and ectopic fat deposition.