Tear glucose is associated with the presence and severity of diabetic retinopathy

To examine the association between tear glucose (TG) and the presence and severity of diabetic retinopathy (DR) in patients with type 2 diabetes mellitus (T2DM).

A cross-sectional study. TG was examined by rapid qualitative test strip in 160 patients. The severity of DR was graded as mild DR and severe DR. The presence and severity of DR were compared between patients with positive and negative TG. The association of TG with the presence and the severity of DR was estimated by multivariable regression analysis and spearman's rank correlation test, respectively. The performance of TG to detect DR was evaluated by the receiver operating characteristic (ROC) curve.

In this study, 160 patients were included, with a median age of 64.0 years, and 88 (55.0%) patients were males. A total of 91 (56.9%) patients had positive TG, and 69 (43.1%) patients had negative TG. In TG-positive group, 41 (45.1%) patients were diagnosed with DR, among them, 8 (19.5%) patients had mild DR, and 33 (80.5%) patients were afflicted with severe DR. Multivariable logistic regression indicated that the presence of DR positively correlated with the presence of positive TG (odds ratio [OR], 3.62; 95% confidence interval [CI], 1.56-8.40; p < 0.01), longer duration of diabetes (OR, 1.11; 95% CI 1.06-1.17; p < 0.01) and higher HbA1c (OR, 1.25; 95% CI 1.01-1.54; p = 0.03). Moreover, Spearman's correlation analysis suggested that the grading of TG increased with the severity of DR (r_s = 0.28, p < 0.01). The area under the curve (AUC) of the model integrating TG, the duration of diabetes and HbA1c was 0.76 (95% CI 0.69-0.84), indicating a fair discriminative ability of DR.

TG level was associated with the presence and the severity of DR. TG might be an easy-to-use, non-invasive parameter to the screening and monitoring of DR among patients with diabetes.