The effects of blood glucose regulation on tear function tests in diabetic patients

To investigate whether blood glucose regulation in patients with diabetes mellitus (DM) has an influence on the ocular surface disease index (OSDI) score and tear function tests such as tear film osmolarity (TFO), tear break-up time (TBUT) and Schirmer tests.

Fifty diabetic patients with a fasting blood glucose (FBG) level greater than 200mg/dL and HbA1c level greater than 10% were recruited for this prospective study. All of the patients underwent a detailed ophthalmic examination including OSDI questionnaire, TFO test, TBUT test and Schirmer test initially. All tests were repeated after obtaining regulation of patients' blood sugar (approximately 6 weeks later).

The mean age of the diabetic patients in the study was 54.96±12.48 years. Initially, the mean FBG, postprandial blood glucose (PBG) and HbA1c levels were 301.40±79.11mg/dL, 431.06±74.47mg/dL and 12.31±1.67%, respectively. After blood glucose regulation; the levels of all parameters (153.78±59.32mg/dL, 252.32±88.34mg/dL and 9.67±1.60%, respectively) statistically significantly decreased (P<0.001). The mean levels of OSDI score, TFO measurement, TBUT test and Schirmer test were 28.38±16.46 points, 349.66±13.09 mOsm/L, 6.44±1.91s and 8.66±3.57mm initially, and 17.82±11.70 points, 314.14±12.80 mOsm/L, 6.62±2.03s and 9.02±3.68mm after blood glucose regulation, respectively. Although the improvements in TBUT and Schirmer test values were not statistically significant (P>0.05), statistically significant reduction was obtained in OSDI scores and TFO levels (P<0.001, for each).

DM, which is a hyperosmolar disorder, appears to cause elevation in OSDI score and increase in TFO level, especially if blood glucose is poorly regulated.