Multifocal ERG defects associated with insufficient long-term glycemic control in adolescents with type 1 diabetes

PURPOSE. To investigate the relationship between long-term glycemic control and localized neuroretinal function in adolescents with type 1 diabetes (T1D) without diabetic retinopathy (DR). METHODS. Standard (103 hexagons) and slow-flash (61 hexagons) multifocal ERGs (standard mfERG and sf mfERG) were recorded in 48 patients and 45 control subjects. Hexagons with delayed responses were identified as abnormal. Negative binomial regression analysis was conducted with the number of abnormal hexagons as the outcome variable. Glycated hemoglobin (HbA_1c) levels, time since diagnosis of T1D, age at diagnosis of T1D, age at testing, and sex were the covariates. Another model replacing HbA_1c closest to the date of testing with a 1-year average was also generated. RESULTS. There were more abnormal hexagons for mfOPs in patients than in control subjects (P = 0.005). There was no significant difference in the mean number of abnormal hexagons for standard mfERG responses between patients and control subjects (P = 0.11). Negative binomial regression analysis for the standard mfERG data demonstrated that a 1-unit increase in HbA_1c was associated with an 80% increase in the number of abnormal hexagons (P = 0.002), when controlling for age at testing. Analysis using the 1-year HbA_1c averages did not result in significant findings. CONCLUSIONS. Poor long-term glycemic control is associated with an increase in areas of localized neuroretinal dysfunction in adolescents with T1D and no clinically visible DR. Stricter glucose control during the early stages of the disease may prevent neuroretinal dysfunction in this cohort.