MUC5AC and Hyperglycemia: Hyperglycemia causes a decrease in conjunctival goblet cell density, a decrease in mucin density, and a decrease in tear film stability, in addition to direct epithelial damage; at the same time, hyperglycemia causes an increase in tear osmolarity, which causes mucin denaturation, a decrease in tear film stability, and yet another increase in osmolarity, creating a vicious cycle.