Despite vaccinations against the virus that causes COVID, many people still get“breakthrough” COVID, some with serious consequences including hospitalization. Those at-risk after vaccination tend to have low antibody levels. Being male, obesity, cardiovascular disease, and type 2 diabetes (T2D) are frequent in fully vaccinated patients who get COVID. This may be because adults with T2D are at risk of having a weaker immune response than people without diabetes. This may be more likely in people with high blood glucose levels.

Does having high blood sugar levels increase risk of breakthrough COVID?

In a new study, researchers studied if, after vaccination, having a high HbA1c level increases risk of a breakthrough COVID infection in fully vaccinated patients. This study was done in Italy among 494 healthcare workers and educators who had T2D and had gotten both doses of the Pfizer vaccine and were monitored for a year. Those with good glycemic control (HbA1c less than 7% over the year) had higher anti-COVID antibody levels compared with those with poor control (HbA1c above 7%). The rate of breakthrough infections was significantly higher among those with poor control. The only other factors associated with infections were smoking and being male.

This suggests that high blood sugar levels above above 7% may harm the immune system and increase risk of a breakthrough COVID infection for adults with T2D. This is on top of a higher risk of severe COVID in people with T2D. These data suggest the urgent need to optimize glucose levels after vaccination against COVID. Further, we need to consider patients with poorly controlled T2D as a high-risk group to be prioritized for booster doses of vaccine.


Photo by Shutterstock.