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

Abstract

Aims To examine the association of HbA_1c 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 HbA_1c, 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, HbA_1c level was 57 mmol/mol (7.4%) and glucose level was 8.8 mmol/l, and 77% were of white European (white participants) and 21% of black African ancestry (black participants). HbA_1c was 0.3% higher in black vs white participants (P1c, glucose, and systolic blood pressure (all P1c in participants with black vs white ancestry [63 mmol/mol (7.9%) vs 58 mmol/mol (7.5%); P1c levels in black people for a given level of average plasma glucose, strategies may be needed to individualize the interpretation of HbA_1c measurements.