People with type 2 diabetes who develop COVID-19 are more likely to need hospitalization for the viral infection if they have a higher A1C level (a measure of long-term blood glucose control), according to a new study published in the journal Diabetes Care.
There is now a large body of research showing that for people with diabetes, overall blood glucose control and specific diabetes treatments are linked to various outcomes related to COVID-19. One study showed that long-term blood glucose control — over two to three years — is linked to the likelihood of needing intensive care for COVID-19. Another study showed that people with type 2 diabetes who take metformin or a sulfonylurea (such as glyburide, glipizide, or glimepiride) may have a lower risk of dying from COVID-19, while those who take insulin may have a higher risk of dying. Having undergone bariatric (weight-loss) surgery is also linked to a lower risk for severe COVID-19, including a lower risk for hospitalization.
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Of course, regardless of your blood glucose control or how you treat your diabetes, an excellent way to reduce your risk for COVID-19 hospitalization is to get vaccinated or boosted according to recommendations. If you’ve been vaccinated originally but not boosted, you should know that a booster shot offers enhanced and lasting protection against severe COVID-19. Receiving a COVID-19 vaccine has been shown not to significantly affect blood glucose control, and also not to raise the risk for a heart attack or stroke. Even if you don’t think you’re at high risk for COVID-19 hospitalization — which may or may not be true — even mild COVID-19 has been linked to a higher risk for ongoing cardiovascular problems.
For the latest study, researchers looked at a group of 39,616 adults with type 2 diabetes, all of them U.S. residents, who developed COVID-19 as confirmed by a lab test or official diagnosis. Participants’ average age was 62, and their average A1C level was 7.6%. The researchers were mainly interested in the link between participants’ A1C level and whether or not they died during the 30-day period following their COVID-19 diagnosis. Aside from that, the researchers were also interested in whether participants required hospitalization, the length of their hospital stay, and whether they needed supplemental oxygen or invasive ventilation (breathing support).
Higher A1C linked to higher risk of hospitalization after COVID diagnosis
The researchers found that a higher A1C level was incrementally linked to a higher risk of hospitalization within 30 days of a COVID-19 diagnosis. The same was true for A1C and the risk of dying — but only up to an A1C level of 8%. At higher A1C levels, the death risk stayed about the same. Similarly, the risk for needing invasive ventilation went up with A1C but then plateaued at A1C levels above 9%. There was no link between A1C level and the length of hospital stay among participants who were hospitalized.
The researchers noted that this study had several limitations, including not knowing how long participants had diabetes — which could have been a factor in the COVID-19 death risk — and not knowing if a participant’s death was specifically related to COVID-19. But since previous research has shown that developing COVID-19 is linked to a higher risk of death from causes that aren’t officially listed as COVID-19, looking at the overall death risk in the wake of a COVID-19 diagnosis may have been a sound approach. Despite these limitations, the researchers wrote, this study represents the largest study of its kind on A1C and COVID-19 outcomes in the United States, so it may offer the best assessment yet of how A1C is linked to these outcomes.
Want to learn more about coronavirus and diabetes? Read our latest COVID-19 updates.
Want to learn more about A1C? Read “How to Lower A1C Levels Naturally,” “How to Lower Your A1C Levels: More Steps You Can Take” and “HbA1c: What It Is and Why It Matters.”
