Mullins et al. (2017) found that neural origin plasma exosomes labeled by L1CAM contained higher pSer312-IRS-1 (ineffective insulin signaling) and lower p-panTyr-IRS-1 (effective insulin signaling) in Alzheimer’s disease. Furthermore, they revealed that higher pSer312-IRS-1 levels were positively related to greater brain atrophy in Alzheimer’s disease and p-panTyr-IRS-1 levels had the opposite effect (Mullins et al., 2017). In a word, exosomes will be the most promising bodily fluid biopsy. As shown in Table 2, some potential exosomal biomarkers can be used to track insulin resistance. Here, L1CAM is linked to Alzheimer disease.