Retinopathy develops at similar glucose levels but higher HbA(1c) levels in people with black African ancestry compared to white European ancestry: evidence for the need to individualize HbA(1c) interpretation

• Type of Material: Article
• Authors: Lisa Staimez, Emory University; Mary Rhee, Emory University; Y Deng, Emory University; Sandra Safo, Emory University; SM Butler, Emory University; BT Legvold, Emory University; SL Jackson, Centers for Disease Control and Prevention, Atlanta; CN Ford, Emory University; Peter Wilson, Emory University; Qi Long, Emory University; Lawrence Phillips, Emory University
• Language: English
• Date: 2020-04-25
• Publisher: WILEY
• Publication Version: Author Accepted Manuscript (After Peer Review)
• Copyright Statement: © 2020 Diabetes UK
• Final Published Version (URL): http://dx.doi.org/10.1111/dme.14289
• Title of Journal or Parent Work: DIABETIC MEDICINE
• Volume: 37
• Issue: 6
• Start Page: 1049
• End Page: 1057
• Grant/Funding Information: This work was supported in part by the Georgia Center for Diabetes Translation Research (P30DK111024).; This work was also supported in part by U.S Veterans Administration award RO1FD003527 (L.S.P.), Veterans Affairs awards HSR&D IIR 07-138 and IK2 CX001907 (L.S.P.) and I01 CX001899 and I01 CX001737 (L.S.P. and M.K.R.), National Institute of Health (NIH) awards R21DK099716 (L.R.S., S.E.S., L.S.P. and Q.L.) DK066204 (L.S.P.), U01 DK091958 (L.S.P. and M.K.R.) and U01 DK098246 (L.S.P.), PCORI award ME-1303-5840 (Q.L. and S.E.S.) and a Cystic Fibrosis Foundation award PHILLI12A0 (L.S.P.). Other support includes the National Center for Advancing Translational Sciences of the NIH under award number UL1TR000454.
• Keywords: Life Sciences & Biomedicine; PREVENTION; RACE; TELERETINAL IMAGING PROGRAM; HYPOGLYCEMIA; VETERANS; MEDICARE; ETHNIC-DIFFERENCES; HEALTH; GLYCATED HEMOGLOBIN; Endocrinology & Metabolism; Science & Technology; DIABETIC-RETINOPATHY

Abstract

Aims: To examine the association of HbA1c and glucose levels with incident diabetic retinopathy according to black African or white European ancestry. Methods: In this retrospective cohort study of 202 500 US Veterans with diabetes (2000–2014), measures included HbA1c, outpatient random serum/plasma glucose, and incident retinopathy [conversion from negative to ≥2 positive evaluations (ICD-9 codes), without a subsequent negative]. Results: At baseline, the study population had a mean age of 59.3 years, their mean BMI was 31.9 kg/m2, HbA1c level was 57 mmol/mol (7.4%) and glucose level was 8.8 mmol/l, and 77% were of white European ancestry (white individuals) and 21% of black African ancestry (black individuals). HbA1c was 0.3% higher in black vs white individuals (P < 0.001), adjusting for baseline age, sex, BMI, estimated glomerular filtration rate (eGFR), haemoglobin, and average systolic blood pressure and glucose. Over 11 years, incident retinopathy occurred in 9% of black and 7% of white individuals, but black individuals had higher HbA1c, glucose, and systolic blood pressure (all P < 0.001); adjusted for these factors, incident retinopathy was reduced in black vs white individuals (P < 0.001). The population incidence of retinopathy (7%) was associated with higher mean baseline HbA1c in individuals with black vs white ancestry [63 mmol/mol (7.9%) vs 58 mmol/mol (7.5%); P < 0.001)], but with similar baseline glucose levels (9.0 vs 9.0 mmol/l; P = 0.660, all adjusted for baseline age, sex and BMI). Conclusions: Since retinopathy occurs at higher HbA1c levels in black people for a given level of average plasma glucose, strategies may be needed to individualize the interpretation of HbA1c measurements.