Will Covid infection dependably trigger high glucose?

Anyone who has lived for a time with diabetes probably has at least one story about high BGs and infection. I’ve had many infections including, sinus, dental, poison oak skin allergy, and bladder to name the ones I can remember, that have driven my blood sugar levels into hyperglycemia.

The PCR test is the definitive test to determine whether you have the virus or not. Perhaps sustained hyperglycemia is an alternate way for us to detect the Covid virus.

I’m thinking if (when) I catch Covid-19, that my blood sugar levels going high and resisting correction will be a secondary and faithful indication of my virus status. With the prevalence of asymptomtic infections, it might even be the first indication that you’re infected. For those of us who monitor our blood sugars every day, I believe we can rely on this indicator.

But my experience may not be representative of our population. Do you think that rising and sustained glucose levels are a reliable indicator that you’ve been infected with Covid? Has anyone here lived with any infection where their glycemia remained normal? If you’ve already had Covid, did your blood sugar levels rise and resist correction? I’m curious about your experience.


If 2nd and booster are any indication, I believe a real infection would cause BG to soar and insulin to be less effective. That’s for me, from the Moderna vac.


The same thing happened to me with both Moderna vaccines.

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@Luis3 and @Mayumi, I hadn’t thought about the post Covid-vaccination BGs. I had no hyperglycemia with my three Moderna shots. I don’t believe my reaction is unique, yet I completely accept both of your reports.

I’m hoping that someone who actually contracted Covid in the last two years can report their blood glucose experience during and after their infection.

The reason I posted this question is that yesterday I found myself with the sniffles, post-nasal drip and sneezing. But these are also symptoms I regularly experience due to seasonal allergies. I felt, however, that my symptoms had ramped up some and crossed over the line between allergies and genuine cold symptoms reported by many people with the Omicron variant.

When I woke up this morning without those cold-like symptoms, I knew I was not infected with the Covid virus. My blood sugar was completely normal yesterday and overnight. It looks like that measure alone could be a faithful indicator of Covid infection in an insulin using diabetic. That’s my hypothesis and reason I posted this question.

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I also did not notice anything after any of my three Moderna doses. I also never had that much of a reaction for any of those jabs. :man_shrugging:

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I had Covid in July of 2020. I was not too sick. I didn’t need to go to the hospital, and I wasn’t coughing or anything. I just had a fever that would come and go for about 2 weeks.

For the most part, my daytime basal was not impacted too much. My nighttime basal increased though.

But meal boluses increased by about 2.5 times normal! The amount of insulin I used was pretty crazy compared to normal. I ended up injecting with a syringe instead of using my pump because I didn’t want to flood the sites.

Lots of things affect BG, like flu or other illnesses. I don’t think there is any reason to use BG in place of getting a test.

I had a fever, which is why I got tested. It wasn’t BG that tipped me off. My insulin needs did not change until a few days after I got my test result.

I think fever is the easiest and most common early indicator. Other symptoms can vary, but I think fever is very common amongst almost everyone that gets Covid.


It just like that some who actually contract Covid have not symptoms and other end up in ICU. We are all different, and that includes how best to manage our blood glucose levels.

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Eric, if you don’t mind answering, were you vaccinated when you caught covid?

While you didn’t answer directly my question about glucose levels during covid infection, I’m guessing that your BG levels were good but your mealtime insulin levels went up a lot, although delayed from the covid start.

I agree with this but my thought is that for people who take exogenous insulin, glucose levels can provide a separate indication of infection. Your experience with responding quickly with more insulin, is that your BG did not go up in response to covid. Yet I’m thinking that it would have if you were not paying close attention to your actual insulin needs.

I’m watching various sources of information for signs and symptoms of this new Omicron variant infection and fever is being reported by fewer people as common a symptom as it was with the Alpha and Delta variants.

Going out to get the PCR test can mean queuing up in long lines, often outside in winter conditions, if media pictures are representative. Using a rapid antigen test comes with its own problems, mostly the incidence of false negatives leading one to believe that they are healthy. It then grants them permission to attend social events thinking that they won’t infect anyone.

I’m trying to figure out if high BGs might be a great indicator for those of us who use external insulin as a way to confirm other signs and symptoms. I know its not scientific and can’t be done with certainty but it might provide a good indication that you’ve caught covid.


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This is an interesting thought.

Do you think that this behavior will be different if you have Covid vs the flu vs RSV?

In my case, it seems as if just about any illness drives my BG up and tries to keep it there. Thus far, knock wood, I have avoided Covid.

Stay healthy!


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I think any infection or illness is likely to drive up your glucose levels, including those you list above. By the way, I had to google, RSV, or respiratory syncytial virus to discover what that term means. I’ll add it to the list of things, as a senior with T1D, that I don’t want to catch!

I am like you and just waiting for it to happen. I mean almost 2 years working with the public with many who don’t want or know how to wear a face mask.
So I have been very lucky and continue to keep my fingers crossed!
The only thing that leads me to believe our blood sugars might go up is many without diabetes in the hospital have had very high blood sugars. Not sure what research is out there to back this but I have seen on the internet that high blood sugars is happening to people who do not have diabetes.
Hope we all are staying safe! Hoping for a better new year!


No, that was way before the vaccine became available! I got it in July of 2020!

Well, restating it - nothing affects my BG levels. The only thing that is affected is how much insulin I use or don’t use! :grinning:

What I mean is, I keep my BG in check.

So in this case, if I had not made a change in the amount and timing of insulin, yes my BG levels would have been affected! But I adjusted to keep my BG in check as much as possible.

But that is basically the same thing you are asking, right?

For me, the increased insulin was a later symptom. After my body was already sick.

The sequence we had was that my son caught it first. Then my other son. Then my wife. It basically went rampant through my family, one after the other. And it was too late to do anything.

I tried isolating, but it was too late. I was the last in the family to get it. We all pretty much caught it before we knew anyone else in the family had it.

I had a fever on a Wednesday. Got a test the next day, on Thursday, and got a positive result on Friday.

I didn’t really see any changes to my insulin requirement until a few days after the positive result. Maybe 5 days after I was infected.

So yes, maybe insulin/BG could be used as a sign. But in my experience it was not the leading indicator. So I would call BG a symptom rather than a sign.

Maybe if you have no other symptoms, and never get a test and one day you start seeing your insulin needs creep up. But…I think that if you have no other symptoms, maybe BG/insulin would also not be affected.

The importance of stress and its effect on BG was made clear to me when my wife (non-diabetic) had open heart surgery. I was in the ICU room when her nurse, Barry the great, used a glucometer on her and drew out a couple of units of rapid insulin.

Barry noticed me watching, and explained that they always do that with any major surgery patients, because the stress causes their BG to spike. She wasn’t super high at 155mg/dl, but, he was keeping a close eye on it.

The stress of injury or illness causes a release of cortisol and other stuff. That causes the liver to dump glucose into the blood.

I know for a fact that any stress, emotional or physical affects my BG.

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I am 2 days past the booster Moderna, and it seems like I am at my normal insulin sensitivity. This is much better than the 2nd shot which caused more insulin resistance lasting 5 days.


I had also never heard of RSV until a week ago. I have a former, elderly (that is, my age …) neighbor who just spent the last week in the hospital with RSV. I’m confident they did ample testing to make sure that it was RSV and not Covid. Yes, something else to worry about …

Stay safe!


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@Sally7 There is a recent article on this subject, where it states as many as 20% of non-diabetic Covid patients who suffered stress hyperglycemia have longer term blood glucose control.


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Yes, two different sides of the same coin.

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I know quite a few people in the UK that are T1’s and got Covid. I think it really matters on the person? But if I remember correctly I think all noticed an increase in BG levels of some kind. And a lot of people said their Bg level went up before they knew they were sick. But it really varied from just a day or two to someone that had an issue for weeks. That person though that had the issue for weeks was sick for weeks.


It probably depends on how consistent your insulin needs are to begin with. As someone with a menstrual cycle and several inflammatory illnesses, my insulin needs are in constant flux in response to my cycle and whatever internal and environmental factors are influencing inflammation. I think a mild infection could potentially get lost in that noise. However, for individuals who do not deal with that kind of fluctuation, I imagine things like getting significant viral illness generally have much clearer impact on blood sugar levels. However, I don’t see how that would differentiate between COVID, flu, colds, etc.


I had covid early on, 2 years ago. I didn’t know what it was at the time. It was relatively mild with 2 days of fever and upper respiratory thing.
I was recovered after about 4 days.
My sugars were tough to manage just like always when I get sick but nothing demonstrably different.

I wouldn’t know I had it at all except I had a car accident. And dislocated a couple of ribs from the seat belt.
They gave me an mri. And it showed some lesions.

So when there was an offer to be tested at work in April 2020, I took it and I had the antibodies for covid 19. I must have had it in January or feb of 2020, but I can’t be sure if I had a completely asymptomatic infection at another time.

It seems to me that any little thing can throw off my blood sugars. It’s not like I would suspect covid if my sugars got higher.