Undiagnosed G6PD deficiency can delay type 2 diabetes diagnosis

A common genetic deficiency that often goes undiagnosed may be putting thousands of Black and South Asian men in the UK at risk of serious type 2 complications by delaying diagnosis of the condition, according to a new study.

Glucose-6-phosphate dehydrogenase (G6PD) deficiency is an X-linked recessive disorder that it is more common in males than females. The G6PD enzyme protects red blood cells (RBCs) from damage. Many deficient individuals are asymptomatic, but triggers (such as infection, certain medicines or some foods) result in the premature destruction of these cells. While not causing diabetes, G6PD deficiency can interfere with the interpretation of HbA_1c blood tests.

Researchers at the University of Exeter and Queen Mary University of London analysed health data from 510,379 people to investigate the population-level impact of undiagnosed G6PD deficiency on type 2 diabetes diagnosis and complications. They estimated that approximately 1 in 7 Black and 1 in 63 South Asian males in the UK carry the G6PD deficiency allele. This compares to 1 in 100,000 White men. However, fewer than 1 in 50 G6DP-deficient males are clinically recognised.

Carriers had considerably lower average HbA_1c compared to non-carriers, while differences in average glucose were negligible. G6PD-deficient men also had a 37% higher risk of developing diabetes-related microvascular complications than non-carriers. It is likely that this is linked to an average 4.1-year delay in type 2 diabetes diagnosis compared to non-carriers.

The investigators have called for greater awareness among healthcare professionals that the use of HbA_1c for diagnosing and monitoring type 2 diabetes may not be accurate for all ethnicities. This may compound the inequities in diabetes outcomes that are already found in these groups.

The full study can be read here.