Comparison of Optical Coherence Tomography Angiography Findings between Healthy Children and Children with Type 1 Diabetes Mellitus and Autoimmune Thyroiditis

This study aimed to compare the development of early diabetic retinopathy (DR) findings, a microvascular complication, between patients with type 1 DM and autoimmune thyroiditis (AT) (group 1), patients with isolated type 1 diabetes mellitus (DM) (group 2), and healthy controls (group 3), who were matched for age, sex, number, and body mass index for comparison. In this prospective observational study, individuals aged 10-20 years were included, and patients in groups 1 and 2 were followed up for ≥5 years. None of them developed clinical DR during the follow-up period. Optical coherence tomography angiography (OCTA) was used to evaluate the foveal avascular zone (FAZ) and parafoveal vascular density (PVD) for the development of early DR among the groups. OCTA findings were compared between patients and healthy controls. Obtained data were analyzed using IBM SPSS Statistics for Windows, version 25.0. The mean FAZ and PVD were significantly different among the three groups (FAZ, p = 0.016; PVD, p = 0.006). The mean FAZ was higher in groups 1 and 2 than in group 3 (p = 0.013 and 0.119, respectively). The mean PVD was lower in groups 1 and 2 than in group 3 (p = 0.059 and 0.007, respectively). No significant difference was found between groups 1 and 2 in terms of the mean FAZ and PVD (p = 0.832 and 0.653, respectively). The mean glycated hemoglobin (HbA1c) level was significantly correlated with FAZ and PVD (FAZ: r = 0.496, p < 0.001; PVD: r = -0.36, p = 0.001). In patients with type 1 DM who did not develop clinical DR, OCTA findings revealed an increase in FAZ, which was associated with higher HbA1c levels. The mean PVD was significantly lower in the group with coexisting AT and type 1 DM than in the control group. These results suggest that the coexistence of AT and type 1 DM can contribute to the development of microvascular complications. Thus, studies with larger patient series are required.