To investigate if the differential expression of the mitochondrial dynamics regulatory proteins coincided with an altered morphological status of the mitochondrial network, we selected six athletes and six type 2 diabetes patients with the highest and lowest GIR per kg FFM during the glucose clamp (mean GIR: 100.5 ± 17.7 μmol kgFFM−1 min−1, n = 6 vs 15.0 ± 3.0 μmol kgFFM−1 min−1, n = 6, respectively) and performed detailed confocal microscopy imaging, using the mitochondrial marker protein TOMM20. Here, TOMM20 is linked to type 2 diabetes mellitus.