[Analysis of the clinical characteristics of dry eye patients with type 2 diabetes mellitus at different disease durations].

Objective: To investigate the clinical characteristics of symptoms and signs of ocular surface lesions in dry eye patients with type 2 diabetes mellitus (T2DM) of different disease durations. Methods: A cross-sectional study was conducted. Consecutive T2DM patients complicated with dry eye who visited the Special Clinic for Diabetic Ocular Surface Diseases at Qingdao Eye Hospital, Shandong First Medical University from January 2020 to December 2024 were enrolled as the T2DM group. Dry eye patients without T2DM from the Dry Eye Clinic and age-and gender-matched healthy volunteers were recruited as the non-T2DM group and control group, respectively. The T2DM group was further divided into four stages according to disease duration: Stage Ⅰ (duration≤5 years), Stage Ⅱ (5 years<duration≤10 years), Stage Ⅲ (10 years<duration≤20 years), and Stage Ⅳ (duration>20 years). Ocular symptoms were evaluated using the Ocular Surface Disease Index (OSDI) questionnaire. Ocular surface function was assessed by corneal sensitivity (CS), corneal fluorescein staining (CFS) score, Schirmer Ⅰ test (SⅠT), tear meniscus height (TMH), non-invasive first tear film break-up time (NIKf-BUT), non-invasive average tear film break-up time (NIKav-BUT), lipid layer thickness (LLT), and meibomian gland loss (MGL) grading score. Anterior segment optical coherence tomography was used to measure central corneal epithelial thickness (CCET) and central corneal thickness (CCT). In vivo confocal microscopy was performed to detect corneal nerve fiber parameters. Spearman's rank correlation analysis was used to evaluate the correlations between variables. Results: A total of 278 T2DM patients (556 eyes) were enrolled in the T2DM group, with a mean age of (60.25±8.71) years, a male-to-female ratio of 117∶161, and a mean disease duration of (11.09±8.02) years; among them, 84 cases were Stage Ⅰ, 81 cases Stage Ⅱ, 90 cases Stage Ⅲ, and 23 cases Stage Ⅳ. The non-T2DM group included 60 patients (120 eyes), with a mean age of (58.52±7.93) years and a male-to-female ratio of 23∶37. The control group comprised 53 healthy volunteers (106 eyes), with a mean age of (58.79±5.73) years and a male-to-female ratio of 21∶32. There were no statistically significant differences in age and gender distribution among the three groups (all P>0.05). Compared with the control group, the T2DM group showed significantly higher OSDI score (31.58%±20.56%), MGL grading score (3.59±0.95) and CFS score (1.84±3.01) (all P<0.05); while significantly lower SⅠT [(5.79±3.10) mm], NIKf-BUT [(5.81±3.14)s], NIKav-BUT [(9.31±4.85)s], LLT [(60.48±16.6) nm], CCET [(51.95±5.56) μm], CS [(56.9±8.30) mm], corneal endothelial cell density [(2 596±465.38)/mm²], and all corneal nerve parameters (including paracentral corneal nerve fiber density and length, etc.) (all P<0.05). Compared with the non-T2DM group, the T2DM group had significantly lower LLT, CCET, CS, OSDI score and all corneal nerve parameters, along with significantly higher MGL grading score and CFS score (all P<0.05); no statistically significant differences were found in SⅠT, NIKf-BUT and NIKav-BUT between the two groups (all P>0.05). In T2DM patients with disease duration≤5 years, compared with the control group, the OSDI score (23.98%±18.21%) and MGL grading score (3.35±0.91) were significantly increased, while SⅠT [(5.65±2.93) mm], LLT, NIKf-BUT and all corneal nerve parameters were significantly decreased (all P<0.05); meanwhile, compared with the non-T2DM group, this subgroup had significantly lower OSDI score and significantly higher MGL grading score (all P<0.05). When the disease duration exceeded 10 years, the OSDI score further increased to be comparable with that of the non-T2DM group, and NIKf-BUT [(5.44±2.92)s], CFS score (2.75±3.25), CCET [(51.36±4.17) μm], CS [(55.21±8.02) mm] showed statistically significant differences compared with both the control group and non-T2DM group (all P<0.05). Spearman's correlation analysis indicated that disease duration was significantly positively correlated with OSDI score, MGL grading score and CFS score, and significantly negatively correlated with NIKf-BUT, CCET, CS and all corneal nerve parameters (all P<0.05). Conclusions: Ocular surface lesion characteristics vary among dry eye patients with T2DM of different disease durations: decreased tear secretion, meibomian gland dysfunction and corneal nerve structural changes occur when the disease duration is ≤5 years, and corneal hypoesthesia and epithelial thinning develop when the duration exceeds 10 years, with lesions gradually worsening as the disease progresses. Compared with non-diabetic dry eye, significant differences exist in meibomian gland function, corneal nerves and epithelial barrier between the two groups.