To compare the corneal endothelial morphology and anterior segment parameters in type 1 diabetes mellitus children (T1DM) and healthy controls. This cross-sectional prospective study included 56 patients with T1DM and 50 eyes of 50 age-matched controls. Endothelial morphology was analyzed with EM-3000 specular microscopy, and anterior parameters were analyzed with Sirius Scheimpflug topography. Endothelial cell density (ECD), coefficient of variation (CV) of cell area, central corneal thickness (CCT), anterior chamber depth (ACD), iridocorneal angle (ICA), K1 and K2, pupillary diameter (PD), horizontal visible iris diameter (HVID), duration of T1DM, and HbA1c levels were noted. The mean age of the T1DM group was 14.3 ± 3.2 years, compared to 13.2 ± 3.7 years in the healthy group (p = 0.140). The mean duration of diabetes mellitus was 4.5 ± 3.5 years. The mean HbA1c was 9.5 ± 1.9% (minimum 6%, maximum 14%). The mean values of CCT were 556 ± 30 μm and 536 ± 36 μm in T1DM and healthy groups, respectively (p = 0.003). The mean values of ACD were 3.69 ± 0.31 mm and 3.83 ± 0.27 mm in T1DM and healthy groups, respectively (p = 0.02). The mean values of PD were 4.29 ± 1.2 mm and 5.17 ± 1.36 mm in T1DM and healthy groups, respectively (p = 0.001). There was no statistically significant difference between groups in terms of ECD, CV, ICA, K1, K2, and HVID (p > 0.05). Type 1 diabetes mellitus children have thicker corneas, shallower anterior chamber depth, and smaller pupillary diameter than healthy subjects.