INS and prediabetes syndrome: We performed a retrospective analysis of 40 participants—19 T2D individuals, 16 healthy obese volunteers (HOVs), and five prediabetes individuals—who underwent [18F]FP-(+)-DTBZ PET to quantify vesicular monoamine transporter type 2 (VMAT2) density [standardized uptake value ratio (SUVR-1)], T1-weighted MRI for 3D morphology metric analysis, and an arginine stimulation test to measure acute (AIRarg) and maximum (AIRargMAX) insulin responses.