COVID-19 Boosters Linked to Blood Sugar Spikes in People With Type 1 Diabetes: Study

High glucose levels in a patient after a COVID-19 booster shot prompted Johns Hopkins doctors to investigate further.

Health care diabetes control. Hand hold injection needle and red bloods background. Blood glucose.

A case of dangerously high glucose levels in a patient following a COVID-19 vaccine booster shot sparked Johns Hopkins physicians to take a closer look, revealing a subtle but significant link between the booster and short-term blood sugar spikes in adults with type 1 diabetes.

First Hint of a Problem

In the summer of 2021, a 24-year-old woman with type 1 diabetes, normally managed on 45 units of insulin daily, was rushed to an emergency room. Heart pounding and breathing rapidly, her blood glucose levels were alarmingly high, and she was unresponsive to her regular insulin protocol.

During her initial day in the hospital, she required 220 units of insulin delivered through her veins—nearly five times her regular dose. Her body began to comply by the third day, her glucose levels cautiously retreating.

Perplexed by the sudden spike in blood glucose levels, doctors ruled out COVID-19 and possible infections for the woman experiencing diabetic ketoacidosis (DKA).

The mystery lingered until Dr. Mihail “Misha” Zilbermint, a Johns Hopkins endocrinologist, noted a crucial detail: The sudden surge occurred just a day after the patient received her COVID-19 vaccine booster shot.

“I reviewed the case extensively, searching for any potential causes of DKA. Nothing seemed out of the ordinary except for the recent COVID-19 shot. It sparked an ‘aha moment,’” Dr. Zilbermint shared with The Epoch Times. “I raced home on my bike and, still in my cycling gear, urgently called my colleague, exclaiming, ‘You won’t believe this!’”

Launching the Investigation

In the wake of that incident, and echoed by other anecdotal accounts, Dr. Zilbermint spearheaded an investigative study, rallying a team at Johns Hopkins to explore the impacts of COVID-19 vaccine booster shots on glucose levels amongst this demographic.

The focused study brought together 21 adult participants with type 1 diabetes—eight received the Moderna booster and 13 the Pfizer-BioNTech booster—and scrutinized changes in their glycemic control and insulin usage around their vaccination time. Employing Dexcom G6 Pro continuous glucose monitors for 10 days, the research sought to accurately track any shifts in glucose levels pre- and post-vaccination.

“To my knowledge, we are the first to explore COVID-19 boosters’ impact on glucose, using 24-hour data from real-time continuous glucose monitoring.” Dr. Andrew Demidowich, assistant professor in the Division of Endocrinology at Johns Hopkins Medicine, told The Epoch Times.

The study illuminated a tangible shift in glucose levels post-vaccination among individuals with type 1 diabetes. The average glucose level of participants rose to roughly 173 from 163 just a couple of days post-vaccination, a jump that’s considered statistically significant and not likely due to mere chance. Researchers also noted a temporary uptick in insulin resistance, hinting that the body wasn’t utilizing insulin as effectively as usual.

While COVID-19 booster vaccines had a generally minimal impact on glucose control, nudging it up by an average of 6 percent, Dr. Demidowich highlighted a critical observation: “One in four participants experienced a pronounced surge in blood sugar levels post-booster.”

However, the study authors stated that, for most patients, the COVID-19 booster remains safe and is well tolerated, aligning with prior research on the primary vaccine series. Dr. Demidowich anticipates a possible, albeit likely milder, blood sugar surge post-vaccine in people with type 2 diabetes, warranting further exploration into the nuanced interplay between vaccinations, immune responses, and glucose control across diabetes types.

This investigation emerges concomitantly with the Centers for Disease Control and Prevention’s (CDC) updated guidelines, which recommend annual COVID-19 vaccinations for everyone older than six months old. The CDC is transitioning the term “booster” to “annual vaccination,” reflecting an adaptive approach to the virus’s ongoing evolution and drawing a parallel with the flu virus.

Deeper Dive Into the Causes

The connection between a spike in glucose levels among type 1 diabetics after a COVID-19 vaccine booster shot isn’t a total surprise, according to Dr. Demidowich.

“Vaccines are designed to provoke an immune response, which induces an inflammatory reaction—known to alter insulin signaling and glucose regulation considerably,” he explained.

For people with diabetes, disruptions such as toothaches or impending infections typically translate to a surge in glucose levels.

Although the study substantiates the theory that insulin resistance, propelled by inflammation, is a key driver for hyperglycemia, it doesn’t present a definitive answer.

Without quantifying inflammatory markers, the team admits the possibility of other contributing factors. The study’s authors point out that “the temporary elevation in glucose levels could be directly related to inflammatory mechanisms, or perhaps to other influences, such as changes in appetite or physical activity levels post-vaccination.”

Practical aspects of vaccination, such as feeling unwell, reduced physical activity, disrupted eating habits, or disturbed sleep, all play a role in glucose dynamics. Dr. Demidowich theorized that any of these factors could collaboratively impact glucose levels following a vaccine booster, weaving a complex picture that necessitates a broader exploration.

Keeping Blood Sugar in Check After Vaccination

It’s crucial for those with diabetes to be mindful of potential glucose level spikes, not just following COVID-19 vaccinations but with all vaccines, owing to the body’s inherent immune response.

“While COVID-19 vaccines didn’t significantly impact glycemia, other vaccines like influenza, Tdap, or pneumococcal might have different effects. It’s crucial to identify patients more susceptible to severe post-vaccination hyperglycemia or DKA,” Dr. Zilbermint said.

Understanding DKA—recognizing its symptoms and knowing how to respond—is paramount. The CDC cites initial DKA indicators as pronounced thirst and frequent urination, with possible quick progression to severe symptoms such as fruity-scented breath, muscle aches, headaches, nausea, and fatigue, to name a few.

“Health care professionals should offer detailed information on the vaccine’s potential impact on blood glucose,” Dr. Zilbermint said, noting that doctors should conduct a pre-vaccination assessment, evaluating the patient’s diabetes management plan to ensure that it’s well controlled.

A strategic post-vaccine plan is vital, particularly during the first five days after the vaccination, Dr. Demidowich advised. He underscored the importance of diligent glucose testing, a solid insulin-adjustment strategy, and establishing a clear benchmark for when to seek professional help, ensuring a safety net for the potentially turbulent glycemic aftermath of vaccinations.