Choroidal Thickness and Hemoglobin A1c Levels in Patients with Type 2 Diabetes Mellitus

Abstract

Purpose: The aim of this study was to assess the correlation of hemoglobin A1c (HbA1c) levels with choroidal thickness in patients with type 2 diabetes mellitus (DM) using spectral domain optical coherence tomography (SD-OCT).

Methods: In this prospective case series, 180 eyes from 90 patients with type 2 DM were classified into three study groups based on HbA1c values: group 1 included patients with good glycemic control (HbA1c $\le$ 7%), group 2 included patients with moderate glycemic control (HbA1c between 7% and 8%), and group 3 included patients with poor glycemic control (HbA1c $\ge$ 8%). Additionally, 50 eyes from 25 non-diabetic subjects were enrolled to group 4 as a control group. Sub-foveal, nasal, and temporal choroidal thickness were measured and compared.

Results: Mean central, nasal, and temporal choroidal thicknesses in diabetic patients (247.80, 238.63, and 239.30 $\mu$ m) were significantly less than non-diabetic healthy subjects (277.56, 262.92, and 266.32 $\mu$ m). Additionally, mean central, nasal, and temporal choroidal thickness values in group 4 (277.56, 262.92, and 266.32 $\mu$ m) were significantly greater than the corresponding values in group 2 (248.34, 237.55, and 236.45 $\mu$ m) and group 3 (239.81, 234.62, and 233.94 $\mu$ m), but was not significantly different from corresponding values in group 1 (259.46, 246.12, and 251.00 $\mu$ m).

Conclusion: HbA1c values have a significant correlation with choroidal thickness in diabetic patients, and better glycemic control with HbA1c $\le$ 7% may prevent choroidal thinning.

Keywords: Diabetes Mellitus; Diabetic Retinopathy; Enhanced Depth Imaging Optical Coherence Tomography; HbA1c; Choroidal Thickness.