Dry eyes in patients with diabetes mellitus.

Dry eyes may be caused by impairment in the tear production or excessive tear evaporation and are associated with photophobia, red eyes, vision impairment, local pain and pruritus. It has been described that patients with Diabetes Mellitus (DM) may have a higher prevalence of dry eyes than normal population. This is a case control study of 120 patients with Diabetes Mellitus (DM) and 120 paired controls aiming to compare their prevalence of dry eyes (by the Schirmer test) and its severity (measured by OSDI or Ocular Surface Disease Index) as well as their association with diseases' clinical variables. We found that 38.3% of DM patients had dry eyes, a prevalence that was higher than controls (p = 0.02). At univariate analysis, they were found to be more common in older individuals (p = 0.001) with type 2 diabetes (p = 0.001) and in those using metformin (p = 0.001). A multivariate linear regression showed that metformin use was the only independent variable associated with dry eyes. When patients with dry eyes with and without DM were compared, no differences in the symptom's intensity were found.