Aberrant C3 activation occurs in inflammatory and oxidative stress condition and participates in the progression of normal aging or neurodegenerative diseases.21, 22, 23, 24, 25 As the most abundant cells in the brain, astrocytes have been considered as one of the major source of C3 under the diseased condition.22, 26 Thus, we suggested that C3 production might be up‐regulated in the astrocytes induced by diabetes or high glucose(HG). Here, C3 is linked to neurodegenerative disease.