A study by the University of Exeter and Queen Mary University of London analysed health records for 510,379 people and found a higher prevalence of G6PD deficiency among Black and South Asian men in the UK. The researchers estimate that around one in seven Black men and one in 63 South Asian men carry the genetic deficiency, compared with fewer than one in 100,000 white men, and fewer than one in 50 G6PD-deficient men are clinically recognised. G6PD is a protein in red blood cells that helps protect them from damage. In people with the deficiency, exposure to certain foods or drugs can cause red blood cells to die early, leading to anaemia and related problems.

Although G6PD deficiency does not cause diabetes, it can affect HbA1c test results, which are used to diagnose and monitor the condition by measuring average blood sugar over two to three months. The researchers say the deficiency can make HbA1c readings appear artificially low, underestimating true blood sugar levels. They report that men with the deficiency have a 37% higher risk of developing serious diabetes complications, including damage to the eyes, kidneys and nerves.

Professor Ines Barroso of Exeter said the findings highlight an urgent need to adjust testing practices and address health inequities. “Doctors and policymakers need to know that HbA1c may be unreliable for people with G6PD deficiency, and routine screening could help identify those at risk,” she said. Dr Veline L’Esperance, a GP and senior clinical research fellow at QMUL, described the results as deeply concerning and called for broader awareness and equitable screening policies. In the UK context, Diabetes UK notes about 5.8 million people have diabetes, with 1.8 million undiagnosed; Black and South Asian people are more likely to have undiagnosed diabetes and to experience poorer outcomes. Anna Morris, the charity’s assistant director of research, said disparities must be addressed to ensure fair access to care, while NIHR’s Dr Esther Mukuka urged action to reduce inequalities through testing.