Reaction to Pfizer Vaccine Dose 1

Pfizer needs to post a clear warning for Type 1’s receiving this (first dose). I’m on MDI. The day after receiving, I started a 4 solid day course of 300-400 blood sugars despite application of sick day rules and constant consultation with my doctor. I had chills and, as you will all expect, dehydration, constant urination. All exactly like onset in 1968, except ketones.
I can’t imagine what the second dose will being.
Has anyone else had this?


Sorry to read about your troubles with the Pfizer vaccination.

I have read about others more severe reaction to the first dose of the vaccine, some from the Moderna version, who suspected that they had a prior asymptomatic infection of Covid-19. Then their vaccination gave them symptoms that better aligned with a reaction from a second dose. Is it possible that you had been infected already?

I hope you feel better soon.

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Thank you, Terry. I think you are on to something. I’m much better now, but not looking forward to the second dose.


I had chills aches and tiredness from my first moderna. Also high sugar. It all resolved in 2 days.

My daughter got the Pfizer shot and had a similar reaction.
Site pain, tired slight fever. Today is her second day and seems probably already over it.

Not sure if everyone knows, you can get vaccines if you are over 50 in California and if you have a family member with you, that person can get it too even if not in current phase.

My daughter is 16 and they gave it to her just because she was there.

Those are the new rules even though they said they will wait till April 1, it’s already been implemented.


Most type 1’s have seemed to be okay with milder reactions, but a small percentage of type 1’s seem to have more severe reactions. I know a bunch on another site in another country that have gotten their first shot. They were told up front to expect a full range of symptoms for 2-3 days. There was one person getting worried because they had a fever and higher blood sugars for 5 days, but it still fit the guidance of what they were warned about.

Everyone ended up being fine, although a couple of them are more worried about the upcoming second shot because your reaction to it is supposed to be worse. Only a few have gotten the second shot and they have all been fine. But one of the complaints has been high blood sugars.

My husband purposely got the J&J and had no side effects at all. He is not a type 1 but had been considered to be a type 2, but his sugars stay in the low 6’s now. If I get one it will probably be the J&J one because I have such a problem with allergies and medications. The J&J one is just the one shot too.

@Sue_R I am type 2 on MDI. I had both Moderna vaccinations. The first I noticed a slight bump in BG but wasn’t sure if it was related. The morning after the 2nd I woke feeling unwell and alternately hot and cold with no fever. Acetaminophen got me through the day enough I could do what needed to be done.

BG was not responding properly to Humalog. It was like I was extremely insulin resistant. I got that jab March 24. As of the 29th I was using more insulin than prior to being vaccinated. It is odd as in taking longer for BG to drop and is quicker to rise.

The feeling ill only lasted the one day. I am glad to have received the vaccination. If I felt this bad for one day and had poor BG control I hate to think what actually contracting Covid-19 would do.

Edit - Another thing that is still worse this morning is Feet on the Floor syndrome. Prior to vaccination both DP and FOTF were minimal. I awoke this morning with BG of 101mg/dl. I take thyroid meds that require fasting and don’t eat for a bit over an hour. BG has risen steadily sitting at 123mg/dl. This is not huge but is higher than before.


I had a very sore arm for my first Pfizer dose, but I didn’t see any big changes in how much insulin I needed. About a week afterward, I needed a bit more insulin but that may have just been due to my monthly hormone cycle.

I got the second dose yesterday. My arm is a little sore, but it is actually not as bad as with the first dose. I’ve remained insulin sensitive so far- if anything, I’ve been a bit more insulin sensitive, but I’m not sure that is related to getting the vaccine.

I’ve read this as well. I am pretty sure I did not contract SARS CoV2 during the last year so perhaps that explains the difference between our experiences @Sue_R. Hopefully your second dose will go more smoothly.


No, this is atypical. Usually people get sick on the 2nd dose.

Its good because it means the vaccine is working.

Maybe you are someone who gets an unusually high immune system kick from the 1st does, plus you are someone who’s blood sugars really react to illness. I know there are lot of people like that (I’m not one of them), but I hear enough people talk about it that I know its a factor.

I wonder what happens with the 2nd dose, too.

Thank you, Marie. I’m glad you’ve talked to so many people.

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Thanks for your response. Maybe the second dose will be gentle to you, unlike what so many people say. My arm wasn’t sore at all.

Thanks for these thoughts.

Curiosity prompts me to ask what thyroid meds you are on that you need to fast for? I ask because I’ve been on 175mcg of thyroxine for 25 years and never been told I need to fast.

@VirginiafromUK I’m not surprised as I wasn’t really informed just to take it when I awoke. Later I learned about continuing the fast.

4. How and when to take levothyroxine

Take levothyroxine once a day in the morning, ideally at least 30 minutes before having breakfast or a drink containing caffeine, like tea or coffee.

Food and caffeinated drinks can both stop your body taking in levothyroxine properly so it does not work as well.

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Well that takes some of the wind out of my sails. I finally have an appointment for my first dose, and I hope to remain excited, rather than apprehensive. If a bad bg response happens, I’ll deal with it.

On an only slightly related subject, I was presented with a gift by my employer, Oregon Health Authority, on Friday. They informed all employees of a new internal email address to which to forward COVID-19 vaccine related complaints. I let fly a scathing note on my gratitude for having cancer, because Type 1 diabetes is inexplicably not considered much of a risk. The cancer qualified me for Phase 1b, Group 6; Type 1 qualifies me for diddly squat. I received a very civilized reply telling me that the CDC now lumps both types in one category, and Oregon will change its criteria. I kinda doubt it - they’ve already distributed their full-color posters categorizing everyone.

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Type 1 LADA here on MDI. No symptoms at all after first Pfizer dose for two weeks. Just slightly sore arm like normal with any vaccine. Normal glucose levels via Dexcom G6 readings and finger sticks. Cautiously awaiting second dose in another week.

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Sorry that happened. I hope your next shot goes better. I had no bg issues with either pfizer shot. I did have high bg before the second shot not related. When I had covid pneumonia last April bg was crashing most of the time.

I am glad I got the pfizer vaccine. It is the most protective against death, severe illness, mild disease and non symptomatic transmission of even the current covid variants as far as we know.


I had no discernible effects with Pfizer doses, thankfully. MDI is inhaled insulin?

MDI = multiple daily injections

I got my 2nd dose of Pfizer on Tuesday, and had maybe a little rise in BG, but nothing definitively related to the vaccine. After the first dose I had about 12 hours with a comically sore arm (like, couldn’t lift a cup to my mouth, had to use the other arm), but still no obvious change in BG. The second dose I hardly noticed my arm, and was just generally a little sore with a mild headache for a day, but Tylenol cleared it right it up and I could go about life like normal.
Obviously everyone is different, but I think those of us with ‘boring’ stories just don’t have fun talking points so we aren’t making the d-news!


I’m T1d for 48 years. Got the Pfizer dose 1 this week. No reaction whatsoever. Sugars have been what I would expect since.