Changes in Central Corneal Thickness with Varying Post-prandial Blood Sugar Levels in Type 2 Diabetics

Abstract

Introduction: Central Corneal Thickness (CCT) affects measurement of Intraocular Pressure (IOP) using Goldmann Applanation Tonometry (GAT). Variation in CCT with blood sugar levels in diabetics could affect IOP measurement and subsequent glaucoma management. CCT has been described to vary with glycaemic levels in diabetics but variation in CCT in the same individuals with variation in the blood sugar levels has not been adequately described. Aim: To study for changes in CCT in patients with Type 2 Diabetes Mellitus (Ty2DM) during hyperglycaemic blood sugar levels in comparison to euglycaemic blood sugar levels and to look for co-relation if any between changes in blood sugar levels and CCT. Materials and Methods: This was a non-interventional crosssectional observational study. Ty2DM patients with Post-Prandial Blood Sugar (PPBS) ≥200 mg/dL underwent CCT measurements using optical biometry. CCT was re-measured a month later when they returned for repeat PPBS estimations. Those patients achieving PPBS values <200 mg/dL and a minimum drop of 50 mg/dL were included for analysis. CCT at each visit was measured within 30 minutes of blood sugar measurement. Paired t-test was used to compare mean changes in CCT and PPBS levels. Pearson correlation coefficient was used to assess the relationship between CCT and PPBS levels. Results: The mean CCT of 89 Ty2DM patients with PPBS ≥200 mg/dL was 501.38±25.28 μm. When the PPBS reduced to <200 mg/dL, the CCT was 502.20±25.05 μm. The difference was not statistically significant (p=0.167). There was no correlation between change in blood sugar levels and CCT (Pearson’s r=0.148). Conclusion: The present study demonstrated no significant change in CCT with varying blood sugar levels in Ty2DM patients. Therefore, in routine clinical practice, the correction for GAT IOP based on a single CCT measurement on one occasion, does not have to be revised depending on glycaemic control in Type 2 diabetics.

Keywords

• diabetes mellitus
• glycaemic state
• goldmann applanation tonometry