Blood Type B Linked to Slightly Elevated Type 2 Diabetes Risk, Major Review Finds

A comprehensive 2024 umbrella review indicates that individuals with blood type B have a slightly elevated risk of developing type 2 diabetes. The review found an an average 28 percent higher risk for people with blood type B (positive or negative) compared to those with non-B blood types.

The study, led by epidemiologist Fang-Hua Liu of Shengjing Hospital of China Medical University, included 51 systematic reviews with meta-analyses. These encompassed 270 health associations related to human blood groups. After re-calculating each association, the researchers identified only one instance of convincing evidence: the link between blood group B and type 2 diabetes mellitus risk.

Individuals with blood type B have an average 28 percent higher risk of developing type 2 diabetes compared to those with non-B blood types.

Unpacking the Research: A Rigorous Evaluation

Human blood is categorized into eight main groups based on antigens (A and B) and Rhesus (Rh) factors. Previous research has explored potential links between these blood cell differences and disease vulnerability. The current umbrella review aimed to systematically evaluate these associations, addressing the need for robust evidence.

To achieve this, researchers conducted extensive searches across six major databases up to February 16, 2024. Their goal was to identify existing systematic reviews and meta-analyses. They then subjected 270 reported links between blood group and disease to stringent statistical tests. These tests assessed evidence strength, consistency, dataset size, and potential for bias. Most associations did not meet the highest standard of evidence, making the finding for blood type B and type 2 diabetes particularly notable.

Putting the Risk in Perspective

While the association between blood type B and an increased risk of type 2 diabetes is considered convincing, the 28 percent increased risk is considered relatively small. To provide context, other lifestyle and dietary factors present significantly higher risks:

• Consuming 50 grams of processed meat daily is associated with a 37 percent increased risk.
• A sedentary lifestyle is linked to a substantial 112 percent increase.
• Being overweight is also recognized as a significant risk factor for type 2 diabetes.

What's Next? Unanswered Questions and Future Research

The 2024 review did not investigate the specific biological mechanism behind this increased risk. However, a separate 2025 study suggests a potential role for the gut microbiome in this relationship, though further research is clearly needed to confirm this.

The findings from this umbrella review suggest a tangible association that individuals can consider regarding their personal risk for type 2 diabetes. Importantly, it also highlights the critical need for more rigorous research into the complex relationships between blood type and disease.