Abstract
Purpose :
Evidence suggests that glycated hemoglobin (HbA1c) levels may be systematically underestimating past blood glucose levels among individuals with sickle cell trait (SCT) and those with glucose-6-phosphate dehydrogenase (G6PD) deficiency, leading to an underdiagnosis of diabetes and diabetes control. However, it is unclear how these genotypes may affect the risk of having diabetic retinopathy (DR). The objective of this study is to evaluate the impact of SCT and G6PD deficiency on HbA1c levels and having DR among a sample of African American females.
Methods :
The African American Eye Disease Study is a population-based, cross-sectional study of 40+ years old African Americans in Los Angeles, CA. HbA1c and random blood glucose were measured using a DCA 2000 Analyzer and HemoCue B-Glucose System. DR was graded according to ETDRS grading of DR based on photography of 7 standard fields of the fundus of each eye. From 1,789 females, DNAs were extracted. Genotype data were obtained for rs334, encoding the sickle cell mutation, and for rs5030868, encoding the G6PD deficiency mutation. Demographic and clinical data including DR severity were compared statistically between those with and without the rs334 and those with and without G6PD deficiency mutation.
Results :
Compared with individuals without SCT (Table 1), individuals with SCT had a higher HbA1c level (6.1 vs. 5.9, P<0.05) and prevalence of diabetes (25.5% vs. 18.2%, P<0.05), despite similar levels of random glucose (P=0.42). The odds of having diabetes in SCT individuals were 1.58 times those of individuals without SCT. The prevalence of DR was lower in SCT individuals (30%) than in individuals without SCT (48%); however, this difference was not statistically significant (P=0.69). For G6PD deficiency, the mean HbA1c level was lower in carriers and deficient individuals than normal individuals (p < 0.001), despite a similar random glucose level (P=0.37). There was no significant difference in the prevalence of diabetes and DR by G6PD genotype (Ps=0.29 and 0.64, respectively).
Conclusions :
Among older African American females, SCT is associated with a higher HbA1c level and prevalence of diabetes but a lower prevalence of DR. G6PD deficiency is associated with a lower level of HbA1c but did not appear to affect the prevalence of diabetes and DR. Further studies with larger sample sizes are needed to confirm these findings.
This abstract was presented at the 2022 ARVO Annual Meeting, held in Denver, CO, May 1-4, 2022, and virtually.