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Wen-Hsiang Lee, Kevin J Moore, Erin C Dunn, Tulay Koru-Sengul; Glycemic thresholds for diabetic retinopathy and implications for diabetic retinopathy screening in the United States. Invest. Ophthalmol. Vis. Sci. 2017;58(8):2908.
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© ARVO (1962-2015); The Authors (2016-present)
Glycemic indices such as Hemoglobin A1c (HbA1c) and Fasting Plasma Glucose (FPG) can provide insight into patient diabetic retinopathy (DR) status. DR is one of the most common microvascular complications of Type I and II diabetes mellitus and affects more than 4 million Americans. The rise in diabetes over the coming decades puts more individuals at risk since diabetes is a leading cause of adult-onset blindness. HbA1c and FPG are used as diabetic diagnostic and progression markers. Using a cross-sectional study design, we evaluated the relationship between glycemic indices and DR to provide glycemic thresholds for clinical suspicion of patient DR status.
We analyzed clinical and sociodemographic characteristics from 5,704 adults (>40 years old) using data from the 2005-2008 National Health and Nutrition Examination Surveys (NHANES), a population-based nationally-representative sample. HbA1c, FPG, and 45-degree color retinal images were assessed. DR was defined as >14 on the Early Treatment Diabetic Retinopathy Study severity scale. Receiver operator curves (ROCs) were generated to obtain the optimal glycemic thresholds maximizing sensitivity and specificity. Statistical analysis was completed using SASv9.4.
Compared to those without DR, patients with DR were on average older, had a higher BMI, larger waist circumference, lower total cholesterol, and higher FPG and HbA1c for the entire patient group. Youden’s Index for identifying DR (maximizing sensitivity and specificity) identified the optimal FPG threshold as 118 mg/dL (sensitivity: 46.3%; specificity: 80.8%; Odds ratio: 1.01; 95% Confidence interval (CI): 1.01 – 1.02). The optimal HbA1c threshold was 6.0% (sensitivity: 55.1%; specificity: 78.2%; Odds ratio: 1.79; 95% CI: 1.68 – 1.90). ROCs revealed HbA1c was a stronger discriminator of DR status compared to FPG (Area under the Curve (AUC): 0.71 vs 0.65).
This study proposes glycemic thresholds to differentiate between patients with and without DR. Health professionals can use these glycemic thresholds to monitor DR status and as a reminder of the importance of diabetic ophthalmologic examinations. Future longitudinal studies are necessary to better discern the ideal glycemic index thresholds to identify and to screen for DR in the clinical setting.
This is an abstract that was submitted for the 2017 ARVO Annual Meeting, held in Baltimore, MD, May 7-11, 2017.
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