Flu shot, Covid booster

Hi. My son is 11. He was diagnosed 4 months ago. We are all planning on getting flu and covid booster this year, but I wonder how significant his blood sugar reaction will be to the vaccines.

Thank you.

1 Like

I have never had problems with vaccinations. I got my flu shot a few weeks ago and will get the most updated COVID booster this weekend. I don’t expect any problems since the others went well (my last COVID shot was June of last year).
Responses vary person to person so you’ll have to wait and see.

I’ve never had a change in my bs for Covid vaccine, tetanus, hep a vaccine, typhoid vax, flu (last 20 years) vaccine, or either shot of the shingles vaccine or polio booster. Plenty of sore arms though.

thank you for the information. great to know :+1:

1 Like

I got a covid booster and flu vaccine on the same day last year and my blood sugar was higher afterwards for a few days, and spiking more post-meals. But it is T1D, after all, and could have been a coincidence, given all the noise in the system to begin with. And it was nothing like how high it was when I actually had COVID–those numbers were so high, so persistently, I could say 100% it wasn’t noise and was due to illness. So, it’s good to be on the lookout and aware, but nothing to worry about or that you couldn’t handle, if it even happened (which I think it’s probably more likely to not have an effect, given what I’ve heard from others).

1 Like

hi - my son was diagnosed at age 12. What we found … anything that prompted a response from his immune system resulted in higher blood sugars. The first time he got sick after diagnosis was really frustrating for us, as no amount of insulin would lower his blood sugar. We now just know when he’s sick, or fighting any kind of immune reaction, his blood sugar does increase So depending on your son, you might see a change in blood sugar.

1 Like

Being diagnosed immunodeficient, I get all my vaccinations every year. I’ve never noticed any marked blood sugar effects. I suppose if you were anxious about it, it could have an effect. (Stress can sometimes affect my blood sugar for reasons I can’t even guess at.)

Everyone’s reactions are different but I have never had a glucose change based on the flu or covid vaccines. Just the sore arm for both.

It can vary a lot, person to person. I have received 5 Covid vaccine injections. None of them affected my blood sugar.

As a T1, never had a problem with the Covid vax, until the one I got last Monday morning.

I’m on a pump & trying out CGMS, and my BS started raising for no reason, in the middle of Monday night.

Tuesday’s BS readings were VERY HIGH, and it didn’t seem like shooting up helped much.

BS started to get better on Weds., but I’m still dealing with lots of unexplained highs. Changed pump needle site, changed bottles of insulin… nothing’s working well, so I think it might be the Covid shot. Not happy at all!

update: he only got the flu vaccine, covid booster was only for 12yr or older. he had a few unexpected highs for a couple days but only a little high no need to bolus. he complained that he bled more than before but not any other effects. thank you all for your replies.


The Novavax booster is limited to age 12 and up, but Pfizer and Moderna are available for kids. There’s a smaller dose for ages 6 months to 5 years, but after that they get the regular adult dose.

It is important that he get it, since the previous two formulations (original COVID-19 and the bivalent booster that combined the original recipe with omicron variant vaccination) are now obsolete. We’re now facing offshoots of the XBB variant, which is what the newest vaccine targets. XBB strains evade protections from the previous vaccines.

1 Like

My reaction to the COVID vaccine was significant. I got all the symptoms for 2 days (fever, aches, GI). My BG shot up to 550. I was able to manage it with help from my doc. The same thing happened with the boosters. I had Moderna each time. I had long term inflammatory symptoms that are finally settling down. I have never had reactions to other immunizations, just sore arm for a day. My recommendation is to monitor closely after the jab.
PS- my endo was not surprised. She said it is an expected response to the vaccine.

@Catham Welcome Catherine to the JDRF TypeOneNation Community Forum!

My reaction to the SARS Coronavirus vaccines were not as dramatic as yours, only a slight BG elevation, but other persons have told me similar stories to what you shared. Your advice to “monitor closely” is right for anything we do that is out of the norm.

A “first” for me was my annual seasonal flu shot, which I get the first week of October every year. Last week, on the day I got my shot and for most of the day after, I was fighting almost continual low BG requiring me to eat extra snacks, Something I’ve not experienced during the decades that I’ve had the annual flu vaccine.

I’ve had five doses of Pfizer, and no reaction to any of them other than a sore arm for a day or so. No reaction to this year’s flu shot (which I got at the same time, in the same arm), either. And I’ve got several other autoimmune issues besides T1D, and I’m incredibly sensitive to a lot of meds. Bodies are highly individual when it comes to drug reactions.

I do get higher blood sugar levels after every vaccination and had a reaction to second COVID-19 vaccine, so skipped the rest.