INS and diabetes mellitus: In this regard, conditions such as diabetes mellitus (DM) and facial palsy (FP) can be important causes of dysfunctional changes in tear volume and/or composition.[11]–[14] In addition, it is also important to consider that hormones, in particular, insulin, thyroid and sex steroid hormones are regulators of LG functions [15]–[18] and that the OS is constantly affected by their related diseases (e.g.; Graves orbitopathy).