Abstract

Background: We investigated the risk of incident diabetic retinopathy (DR) among high glycator compared to low glycator patients based on the hemoglobin glycation index (HGI). Visit-to-visit variations in HGI also were assessed. Methods: Glycated hemoglobin (HbA 1c ) and continuous glucose monitoring data were collected up to 7 years prior to the date of eye examination defining incident DR or no retinopathy (control). Hemoglobin glycation index was calculated as difference in measured HbA 1c and an estimated A 1c from sensor glucose (eA 1c ) to define high (HbA 1c − eA 1c >0%) or low (HbA 1c − eA 1c <0%) glycator. Stable glycators were defined as ≥75% of visits with same HGI category. Logistic regression was used to assess the association between glycation category and incident DR. Results: Of 119 adults with type 1 diabetes (T1D), 49 (41%) were stable low glycator (HbA 1c − eA 1c <0%), 36 (30%) were stable high glycator (HbA 1c − eA 1c >0%), and 34 (29%) were unstable glycator. Using alternate criteria to define high vs low glycator (consistent difference in HbA 1c − eA 1c of > 0.4% or <0.4%, respectively), 53% of the adults were characterized as unstable glycator. Compared to low glycators, high glycators did not have a significantly higher risk for incident DR over time when adjusted for age, T1D duration and continuous glucose monitoring (CGM) sensor type (odds ratio [OR] = 1.31, 95% confidence interval [CI] = 0.48-3.62, P = .15). Conclusions: The risk of diabetic retinopathy was not found to differ significantly comparing high glycators to low glycators in adults with T1D. Moreover, HbA 1c − eA 1c relationship was not stable in nearly 30% to 50% adults with T1D, suggesting that discordance in HbA 1c and eA 1c are mostly related either HbA1c measurements or estimation of A1c from sensor glucose rather than physiological reasons.