Getting a COVID-19 vaccine doesn’t have any significant overall effect on blood glucose control in people with diabetes, although short-term vaccine side effects can worsen glucose control in people with type 1, according to a new study published in the journal Diabetes Care.
Nearly two years into the COVID-19 pandemic, there is a mountain of evidence that people with diabetes are especially likely to experience poor outcomes if they develop the viral infection — including hospitalization, admission the intensive care unit (ICU), and death. The risks associated with the infection are higher in people with a history of less than optimal blood glucose control. At the same time, there is strong evidence that the widely available COVID-19 vaccines provide strong protection against the worst outcomes of infection, and that they are extremely safe — with studies showing that vaccination doesn’t raise the risk for stroke or heart attack in older adults, and that it even reduces the risk for death from causes other than COVID-19. Even with the recent approval in the United States of oral drugs to treat COVID-19, vaccines remain a critical tool to prevent the infection and its most damaging outcomes.
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All of this evidence strongly supports getting recommended doses of the COVID-19 vaccine for people with diabetes. At the same time, researchers are constantly monitoring potential side effects of the vaccine. For the latest study, they looked at whether vaccination had any effect on blood glucose control in 74 people with diabetes — 58 with type 1, and 16 with type 2 — who wore a continuous glucose monitoring (CGM) system. As noted in an article on the study at Medical Dialogues, the average age of participants with type 1 was 40, and the average age for those with type 2 was 61. The vast majority of study participants, 87%, received the Pfizer-BioNTech vaccine, while 6% received the Moderna vaccine and 7% received the AstraZeneca vaccine (which is not available in the United States — the study took place in Austria).
COVID-19 vaccine not found to worsen overall glucose control
The researchers looked at CGM data from two days before until three days after participants’ first vaccine dose. Overall, there were no significant differences in time spent within a target glucose range of 70-180 mg/dl over the span of days, suggesting that the vaccine didn’t worsen overall glucose control. This was true both for participants with type 1 and for those with type 2 diabetes. For participants with type 1, though, people who experienced vaccine side effects spent significantly less time in the target glucose range on days when they experienced these side effects. But experiencing side effects didn’t increase the amount of time spent below the target glucose range — suggesting that higher, rather than lower, glucose levels were the main risk linked to these side effects. That’s important because hypoglycemia (low blood glucose) can be especially dangerous in people with type 1, who depend on injected or infused insulin to maintain blood glucose levels. In people with type 2, vaccine side effects were not linked to any blood glucose changes.
The researchers concluded that any effects of the COVID-19 vaccine on blood glucose control were negligible in the study population, and appeared to be limited to higher glucose levels in some people with type 1 when they experienced vaccine side effects. While it’s important for everyone with diabetes to monitor their blood glucose carefully after making any medication changes — including receiving a vaccine — this study demonstrated that in most cases, people with diabetes don’t have to worry about dramatic or dangerous blood glucose changes after receiving a COVID-19 vaccine. But more studies with larger numbers of participants, and including different types of COVID-19 vaccines, are needed to confirm these results.
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