Changes in the tear proteins of diabetic patients

BACKGROUND: Previous studies have shown a significant increase in tear protein peaks in the tears of diabetic patients suffering from dry eye. The aim of this study was to analyze the tear protein patterns from patients with diabetes mellitus who do not suffer from ocular surface diseases (DIA). METHODS: A total of 515 patients were examined in this study (255 healthy subjects (controls) and 260 patients suffering from diabetes mellitus). Tear proteins were separated by sodium-dodecyl-sulfate polyacrylamide gel electrophoresis. After digital image analysis densitometric data files were created and subsequently used for multivariate statistical procedures. RESULTS: A significant increase in the number of peaks was detected in diabetic patients compared to controls (P < 0.0003). The analysis of discriminance revealed a highly significant discrimination between diabetic patients and controls (Wilks lambda: 0.27; P < 0.000001). Furthermore, a significant difference in the protein pattern of diabetic patients could be detected between those suffering from dry eye or not (P < 0.002). The changes in protein patterns of diabetic patients increased with the duration of the diabetic disease. In diabetic patients with a disease duration longer than 10 years the changes were significantly more expressed than in patients with a shorter diabetic history (P < 0.003) and in healthy subjects (P < 0.0001). CONCLUSIONS: The tear protein patterns of diabetic patients are very different in the number and intensity of spots from those of healthy subjects. Furthermore, it could be demonstrated that the differences found in the tear patterns of diabetic patients are not equal to those found in previous studies in patients suffering from dry-eye disease. The alterations in the diabetic tears were correlated with the duration of the diabetic disease. With longer disease, history changes in the tear protein patterns increased. With the course of the disease some protein peaks appeared that are not present in healthy persons. Our study shows that the analysis of electrophoretic tear protein patterns is a new non-invasive approach in the early diagnosis and analysis of the pathogenesis of diabetes induced ocular surface disease.