Objective: To research whether central corneal thickness (CCT) of children with Type 1 diabetes mellitus (T1D) is different from healthy children at same age group and whether metabolic control has an effect on corneal thickness. Materials and methods: The children with T1D who applied to our outpatient department with the aim of controlling for possible diabetes complications and who had no diabetic retinopathy were prospectively evaluated. The healthy children from the same age group who applied to our outpatient setting for eye control and who had no systemic or eye disease were included in the control group. The CCT of all children was measured with ultrasonic pachymeter with topical anesthesia. Findings: While the corneal thickness for healthy children was 554.25+/-42.85 (500 and ndash; 678 and micro;), the average corneal thickness for diabetic children was 567.38+/-33.28 (487 and ndash; 628 and micro;). A significant difference was detected for average corneal thickness (Z=-2.040 p=0.041). No relation was detected between the central cornea thickness and the duration of diabetes (t=1.418 p=0.168), average HbA1C level (t=1.261p=0.218), hyperglycemia (t=0.228 p=0.821) and hypoglycemia attack number (t=-0.332 p=0.743). Result: CCT is increased in the patients compared to the control group even before diabetes mellitus (DM) has developed a retinopathy. A relation of this increase with period of diabetes, HbA1C level and hypoglycemia attack number could not be detected. [Arch Clin Exp Surg 2015; 4(3.000): 148-152]