Retinopathy develops at similar glucose levels but higher HbA1c levels in people with black African ancestry compared to white European ancestry: evidence for the need to individualize HbA1c interpretation

L. R. Staimez, M. K. Rhee, Y. Deng, S. E. Safo, S. M. Butler, B. T. Legvold, S. L. Jackson, C. N. Ford, P. W.F. Wilson, Q. Long, L. S. Phillips

Research output: Contribution to journalArticlepeer-review

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.

Original languageEnglish (US)
Pages (from-to)1049-1057
Number of pages9
JournalDiabetic Medicine
Volume37
Issue number6
DOIs
StatePublished - Jun 1 2020

PubMed: MeSH publication types

  • Journal Article
  • Research Support, Non-U.S. Gov't
  • Research Support, N.I.H., Extramural
  • Research Support, U.S. Gov't, Non-P.H.S.

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