Retinal multispectral imaging of ‘sub-clinical’ capillary micro-aneurysms in non-diabetics correlates with insulin resistance

Abstract

Insulin resistance (IR), short of diabetes mellitus, negatively impacts retinal vessel health. The purpose of this study was to evaluate the correlation between the number of sub-clinical retinal micro-aneurysms (MA#) identifiable by highly sensitive 580 nm multi-spectral retinal imaging (MSI 580 nm) and serological and calculated IR measures. Thirty (n=19 M; n=11 F) non-diabetic optometrists (n=54 eyes), 53.5 ± 7.6 years, were imaged at a professional conference using multispectral imaging (MSI) of the retina (RHATM, Annidis Corporation, Ottawa, Canada). A six parameter blood panel requisition: fasting glucose (FBS), 2 hr glucose (GTT) tolerance, HbA1c, fasting insulin, 2 hr insulin and 25 OH vitamin D liver reserve status were provided to each participant. MSI retinal images were reviewed and the MA# in the central 30 degrees were counted. The calculated clinical parameters used to diagnose IR were most highly correlated with retinal MA#, specifically insulin sensitivity. Subclinical MA#, less visible to non-spectral cameras but observed with multispectral imaging, correlate with insulin, pancreatic function and calculated measures of IR, more closely than FBS and vitamin D status. Future diabetes intervention research should focus upon MSI MA# and IR as actionable pre-diabetes and pre-retinopathy risk factors.