This hypothesis was supported by research studies showing that hyperglycemia increases the expression of proinflammatory cytokines, such as tumor necrosis factor alpha (TNF-α) and interleukins (IL-1, IL-4 and IL-6), even though the detailed mechanism underlying their influence on the integrity and permeability of the BBB has not yet been determined [12]. This evidence concerns the gene TNF and Hyperglycemia.