Blood Type B Linked to Higher Diabetes Risk, Sweeteners Tied to Cognitive Decline

People with blood type B have a slightly higher risk of developing type 2 diabetes than people with non-B blood types, according to a 2024 umbrella review. Meanwhile, a separate long-term study found that higher intake of several widely used artificial sweeteners was linked to faster cognitive decline, especially in people under 60 and those with diabetes.

The umbrella review, which included 51 systematic reviews with meta-analysis articles covering 270 associations, found convincing evidence for an association between blood group B and type 2 diabetes mellitus risk compared with the non-B blood group. The increased risk is about 28 percent on average, which is much smaller than the risk associated with diet, weight, or lifestyle. Just 50 grams of processed meat a day, for example, increases the risk of type 2 diabetes by 37 percent, while a sedentary lifestyle can increase the risk by 112 percent.

In the cognitive study, researchers followed 12,772 adults from across Brazil for about eight years. Participants were 52 years old on average. The study examined seven widely used sweeteners: aspartame, saccharin, acesulfame-K, erythritol, xylitol, sorbitol, and tagatose. After adjusting for factors such as age, sex, high blood pressure and cardiovascular disease, the researchers found that the highest intake group declined 62% faster in overall thinking and memory than the lowest intake group. The difference was roughly comparable to about 1.6 years of aging.

The pattern was strongest among people with diabetes. When the data were analyzed by age, a clearer pattern emerged among participants younger than 60. In this group, those who consumed the most sweeteners experienced steeper drops in verbal fluency and overall cognitive performance compared with those who consumed the least. No significant association was observed among adults older than 60.

Looking at individual sweeteners, higher consumption of aspartame, saccharin, acesulfame-k, erythritol, sorbitol and xylitol was linked to faster declines in overall cognitive function, especially memory. Tagatose was the only sweetener studied that did not show an association with cognitive decline. The study does not show that sweeteners directly damage the brain, but instead highlights an association that remained even after researchers accounted for major health factors that can affect cognition.

The blood type research, published in BMC Medicine, did not examine what might drive the increased diabetes risk for people with type B blood. A 2025 study suggests that the gut microbiome may be involved, though further investigation is needed. The researchers systematically searched multiple databases to identify systematic reviews with meta-analyses of observational studies evaluating associations between ABO as well as Rh blood groups and diverse health outcomes.

More broadly, the blood type study highlights weaknesses in existing research that better-designed reviews can address, and shows that more rigorous work is still needed to understand how blood type relates to disease. The cognitive study authors noted several limitations, including that the analysis did not cover every type of artificial sweetener available and that dietary information was self-reported, meaning participants may not have recalled their food and beverage intake with complete accuracy.