Abstract
Purpose :
It is well established that the mfERG is altered in type 2 diabetes (T2DM). The P1 implicit time (IT) becomes delayed even before retinopathy is present. This is thought to be from the duration of damage to retinal cells from hyperglycemia. However, patients withT2DM and prediabetes also have changes in fasted insulin values. The impact of elevated or reduced blood insulin on the mfERG has not been explored. Here we evaluate the effect of fasted blood insulin levels on mfERG parameters in patients with and without T2DM and prediabetes.
Methods :
32 subjects (age 49.1 ± 10.1) were included in this cross-sectional study. All were fasted upon presentation. HbA1c was taken and used to categorize subjects into groups as controls (<5.7), prediabetes (5.7-6.4) or T2DM (>6.4 or previously diagnosed). No subjects were taking exogenous insulin. Participants self-reported medications and duration of T2DM. All subjects had a visual acuity of at least 20/40. A mfERG (103 hexagons) was performed (VERIS 6.3) with 4-minute m-sequence at near 100% contrast. Single iteration of artifact removal was implemented, and data was evaluated for the foveal hexagons, as well as averaged together for IT and amplitude. Fasted blood glucose and insulin levels were determined. Insulin was analyzed via ELISA (Mercodia). Health of the eye was evaluated via fundus photography and one subject with T2DM who had retinopathy was excluded from multivariate regression analysis. Data were evaluated through ANOVA for comparisons of groups and as well as with multivariate regression analysis.
Results :
There were significant differences in mfERG IT between those with diabetes and those without (T2DM v. prediabetes and controls, P<0.002). There was a strong correlation between increased fasting blood glucose and delayed IT (P<0.002). There was also a relationship between averaged mfERG IT and reduced blood insulin concentration (P=0.035) after age, T2DM duration and blood glucose were controlled for in a multivariate regression.
Conclusions :
Reduced blood insulin correlates with IT delays, which suggests lack of insulin may negatively affect retinal function. More work is needed following subjects with varied insulin levels over time to confirm the relationship between blood insulin and retinal function.
This abstract was presented at the 2024 ARVO Annual Meeting, held in Seattle, WA, May 5-9, 2024.