Blood groups A, B and AB tied to higher diabetes risk

Women with the blood group A, B and AB are at a higher risk of developing diabetes compared with women who have group O blood, a new study has found.
The study of more than 80,000 women found a 35 per cent increased risk of type 2 diabetes in those with group B, Rhesus factor positive (R+) blood compared with the universal donor group O, Rhesus factor negative (R-).
In the research, Dr Guy Fagherazzi, and Dr Francoise Clavel-Chapelon, Center for Research in Epidemiology and Population Health, INSERM, Villejuif, France, and colleagues took data from 82,104 women from a large prospective cohort in France followed between 1990 and 2008.

The objective of the new study was to evaluate the relationship of ABO blood type (A, B, AB and O), Rhesus factor (positive or negative) and a combination of the two with type 2 diabetes (T2D).
The results showed that, compared with women with group O blood, women with group A were 10 per cent more likely to develop T2D, and those with group B were 21 per cent more likely (both statistically significant).
The AB group was 17 per cent more likely to develop T2D, but this result was not statistically significant, researchers said.

When looking solely at R+ versus R- women, neither group was at increased risk of developing T2D compared with the other.

The authors then combined ABO group and Rhesus group and compared each possible combination with O negative (O-), which is known as the universal donor group.
Compared with O- women, the highest increased risk of developing T2D was found in B+ (35 per cent increased risk), followed by AB+ (26 per cent), A- (22 per cent), A+ (17 per cent). The results for O-, B-, and AB- groups were not statistically significant.
"The present study shows for the first time in a large prospective cohort that specific ABO blood groups are associated with an increased type 2 diabetes risk," said Fagherazzi.

The authors said that the reasons behind the association are currently unknown, but could be related to a number of factors: it has been suggested that the human ABO locus might influence endothelial or inflammation markers.
ABO grouping is also associated with various molecules known to be connected to T2D, and a recent paper concluded that ABO grouping is a factor which determines the overall gut microbe composition, which in turn affects metabolism and thus could be related to T2D.
"Our study population included only women but, to our knowledge, no biological mechanisms are likely to explain a sex-dependent association," said Clavel-Chapelon.

The study is published in Diabetologia.