Voxel placement and resulting spectrum. Sagittal (a–c) and axial (d,e) T1 images showing voxel placements for the right anterior insula (ant ins), right posterior insula (post ins), and anterior cingulate (ACC). (f) Representative magnetic resonance spectrum from the posterior insula using MEGA-PRESS spectral editing technique. Combined measure of glutamate and glutamine (Glx) is resolved at 3.8 ppm, γ-aminobutyric acid (GABA) at 3.0 ppm with an inverted N-acetylaspartate (NAA) peak at 2.0 ppm. DN, diabetic neuropathy; HC, healthy control; thal, thalamus.