The purpose of this study was to determine whether low tear production in patients with diabetes mellitus (DM) was related to autonomic nervous system abnormalities, to Sjögren's syndrome, as suggested by a previous study, or to other factors.
Cross-sectional study assessment of patients with DM.
One hundred patients with diabetes mellitus (DM) attending the University of Alberta Outpatient Education Program for DM were consecutively included. All patients were assessed for keratoconjunctivitis sicca with a questionnaire. Tear production was assessed with Schirmer tests and patients with abnormal findings were further examined by an ophthalmologist. The effect of possible confounding factors was also evaluated: all patients underwent standard tests for the diagnosis of autonomic neuropathy and laboratory tests including lipid profiles, fasting blood glucose and levels of HbA1C. Antinuclear antibodies (ANA) were determined using HEp2 cells and various substrates for specific autoantibodies.
Twenty-one of the patients had symptoms compatible with keratoconjunctivitis, and 25 had an abnormal Schirmer test. None of these 25 had abnormal corneal staining. Sixty one patients had evidence of autonomic neuropathy. Antinuclear antibodies were detected in 6 patients and anti-Ro in one other. Multiple regression analyses using the Schirmer test as a dependent variable, and controlling for all the independent variables, showed an association with autonomic neuropathy. No significant associations were observed with the other variables, including the presence of autoantibodies.
Our results suggest that the low tear production seen in some DM patients is related to disfunction of the autonomic nervous system and not commonly to Sjögren's syndrome.