Background: Diabetic retinopathy (DR) is the leading cause of blindness among the working-age population. The earliest morphological manifestation of the disease is pericyte loss, as shown by animal models. Aims: The purpose of this study was to evaluate the presence of pericytes in vitreous samples (VS) from diabetic and nondiabetic patients. Methods: VS from 125 patients with and without diabetes were analyzed. Thirty-three of the VS contained blood vessels and were therefore included in further analysis. Pericyte status was evaluated using a-smooth muscle actin and quantified using the following scoring system: total loss (3), > 50% loss (2), < 50% loss (1), and no loss (0). Results: Of the 33 VS, 29 samples were from patients with diabetes and 4 from nondiabetic patients. Six diabetic cases had a score of 1, 8 diabetic cases had a score of 2, and 15 cases had a score of 3. A positive correlation between glycemia levels and pericyte loss was observed (p = 0.0016; Spearman's r = 0.61). Moreover, all nondiabetic cases had a score of 0 (sensitivity and specificity = 100%). Conclusion: Pericyte loss in VS might be a sensitive and specific marker of DR that correlates with glycemia levels. Furthermore, VS, which are currently discarded, may contain valuable information for diabetic management. (C) 2016 S. Karger AG, Basel