GFAP and non-proliferative diabetic retinopathy: The upregulated expression of the glial fibrillary acidic protein (GFAP) is an early sign of reactive gliosis, and increased GFAP expression can be detected in the aqueous humour of NPDR patients, the retina of DR mice, and the LPS-treated glial cells in vitro [74–76], this suggests the pivotal role of gliosis in the progression of DR.