Effect of glycaemic control on corneal parameters among type 2 diabetes mellitus

Abstract

Purpose: To study the effect of glycaemic control as demonstrated by the change in HbA1c on corneal parameters among patients with type 2 diabetes mellitus (T2DM). Study design: Prospective study analysing corneal parameters among patients with T2DM along with fluctuations in HbA1c.Methods: A prospective, single-centre, cohort study was carried out on T2DM patients with HbA1c > 6.5% from Kasturba Hospital, Manipal, India. The subjects underwent a comprehensive eye examination. One-hundred and twenty-two subjects who fulfilled the inclusion criteria were analysed using the Huvitz 9000A to measure anterior corneal curvature followed by ultrasound pachymetry to measure central corneal thickness (CCT) at baseline and after 3 months. A simple linear regression was used to compare the mean corneal parameters, CCT and anterior corneal curvature, for each group with the mean HbA1c. The mean difference was considered statistically significant only if the value was p < 0.05.Results: We observed a significant difference between baseline and follow-up levels of HbA1c (t = 2.487; df = 53; p < 0.05). Simple linear regression analysis showed a positive correlation and revealed a mean increase in CCT of 1.893 μm (p < 0.001) and a mean increase in anterior corneal curvature of 0.069 D (p < 0.005) for every unit increase in HbA1c.Conclusions: The present study showed that changes in CCT and anterior corneal curvature occur with respect to changes in HbA1c level. Thus, careful attention is required in considering HbA1c status when performing comprehensive eye examinations in diabetic patients.