Correlation patterns of insulin sensitivity or insulin resistance indices vs. HbA1c with ten macular retinal layer thicknesses in a non-diabetic population

Abstract

Purpose : Impaired glucose homeostasis characterized by increased insulin resistance/decreased insulin sensitivity is a risk factor for type 2 diabetes. We aim to investigate the correlation of static insulin sensitivity indices (ISI) and insulin resistance indices (IRI) with ten retinal layer thicknesses in optical coherence tomography (OCT) macular volume scans and compare the correlation patterns with that of HbA1c in non-diabetic participants.

Methods : From the population-based, sex- and age-stratified LIFE-Adult study, non-diabetic participants were included. The static ISI (Avignon, Li, McAuley, and QUICKI) and IRI (HOMA2-IR) were calculated. Reliable OCT scans (97 horizontal B-scans with 512 A-scans each) with B-scan quality ≥ 20 dB were obtained and automatically segmented into ten layers: retinal nerve fiber layer (RNFL), ganglion cell layer (GCL), inner plexiform layer (IPL), inner nuclear layer (INL), outer plexiform layer (OPL), outer nuclear layer (ONL), myoid zone (MZ), ellipsoid zone and outer-photoreceptor segment combined (EZ+OS), interdigitation zone (IZ) and retinal pigment epithelium layer (RPE). Age-adjusted pointwise partial Pearson correlation was conducted between retinal layer thicknesses with indices and HbA1c for comparison with p values adjusted for multiple comparisons.

Results : A total of 5532 eyes of 2787 participants (55.2±11.5 y/o) were included. The correlation patterns (Figures 1) of ISI (Avignon, Li, McAuley, and QUICKI) were similar, with a positive correlation in ONL and MZ, and a negative correlation in EZ+OS and IZ. For IRI (HOMA2-IR), a negative correlation in GCL, IPL, ONL and MZ, and a positive correlation in IZ were observed (Figure 2). Both the correlation patterns of ISI and IRI with retinal layer thicknesses had higher percentages of significance than that of HbA1c in ONL, MZ, EZ+OS, and IZ.

Conclusions : The correlation patterns of ISI and IRI with retinal layer thicknesses indicated that higher insulin sensitivity was related to thicker ONL and MZ, and thinner EZ+OS and IZ. Higher insulin resistance showed an opposite relationship in ONL, MZ, EZ+OS, and IZ, and an association with thinner GCL and IPL. The correlations of ISI and IRI with retinal layer thicknesses were more pronounced than that of HbA1c, indicating the early-stage association of insulin utility status and retinal layer thicknesses.

This is a 2021 Imaging in the Eye Conference abstract.