Associations of glycated hemoglobin (HbA1c) level with central corneal and macular thickness in diabetic patients without macular edema

Objective. To determine the correlation between central corneal thickness (CCT) and central macular thickness (CMT), and fasting plasma glucose levels and HbA1c levels before diabetic macular edema (DME) in type 2 diabetes mellitus (DM) patients without diabetic retinopathy. Methods. Forty-four eyes of subjects diagnosed with type 2 DM, and 45 healthy control subjects participated in this study. Detailed ophthalmologic examination was performed with all participants. CMT was measured in both groups by Spectral-domain optical coherence tomography. CCT measurements were made with an Echoscan US-500 ultrasonic pachymeter. Blood biochemical tests for glycated hemoglobin (HbA1c) and fasting plasma glucose levels were run on all patients. Results. The results of the study showed that the mean CCT was significantly thicker in type 2 DM patients 563.84 ± 33.25 μm than in the controls 550.13 ± 28.41 μm (p = 0.039). The mean of CMT was 231.27 ± 37.74 μm in the study group and 225.38 ± 38.33 μm in the control group (p > 0.05). No relationship was found between CCT and CMT and HbA1c level in the study and control groups. Conclusions. The mean CCT was significantly thicker in type 2 DM patients without diabetic retinopathy than in the controls. The mean CMT is thicker in type 2 DM patients without diabetic retinopathy patients than in the controls, but this difference was not statistically significant. Optical coherence tomography can be a perfect detector for early detection of DME.