Evaluation of retinal microvascular changes in patients with prediabetes

Diabetic retinopathy is a chronic progressive complication with neuronal cell and retinal microvascular involvement and is closely associated with blood sugar and blood pressure levels. Studies have shown that retinal neural dysfunction takes place before the microvascular changes in patients with Type 2 diabetes mellitus. The aim of this study is to compare the retinal microvascular changes of patients who are at the prediabetes stage and healthy volunteers.

Our study included 41 patients with prediabetes who were referred to the internal medicine outpatient clinic and 47 healthy volunteers. All patients underwent ophthalmologic examinations, including best visual acuity, intraocular pressure measurement, slit-lamp examination, and dilated fundus examination. Refractive error measurements were performed with the same automatic refractor-keratometer device. Typically, 3 × 3 mm macular images centered on foveola were obtained by using XR Avanti Optical Coherence Tomography Angiography with AngioVue (RTVue XR AVANTI, Optovue, Fremont, CA, USA) device. In the statistical analysis of the measurements, it was examined by Kolmogorov Smirnov test. Conditions expressed as IFG or IGT are considered as prediabetes; IFG is defined as fasting blood sugar to be between 100 and 125 mg/dL, while IGT is the condition in which the second hour value of the oral glucose tolerance test is 140-199 mg/dL.

There was no statistically significant difference between the control and pre-DM groups in terms of mean age. The distribution of males and females between groups was statistically similar (P = 0.087). In the pre-DM group, 24 (58.6%) patients had IFG, 16 (39.0%) had IFG + IGT, and 1 (2.4%) had IGT. There were no statistically significant differences between the groups for the nonflow area (NFA) and the foveal avascular zone (FAZ) area (P > 0.05). The mean values of superficial and deep capillary plexus (DCP) density were not statistically significant differences between the groups. No statistically significant difference was found between the control group and pre-DM group in terms of the mean measurements of clinical ocular findings (P > 0.05). Retinal thicknesses were also not statistically significant differences between the groups (P > 0.05).

All of the retinal measurements of both patients with prediabetes and healthy volunteers are similar. We did not find any difference between prediabetes and control groups. The ophthalmologic examinations which contain best-visual acuity, intraocular pressure measurement, slit-lamp examination, and dilated fundus examination are similar.