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How does getting sick affect your blood sugar?

Hi everyone,

I'm curious to know whether anyone has noticed an impact of sickness/illness on their blood sugar levels? I finally caught COVID in January and the impact on my blood sugar levels really shocked me. I'm fortunate enough to have a CGM, so I was able to see everything that was going on with my blood sugar levels.

I'm hopefully posting a photo of my CGM charts - on the left is my "typical" blood sugar levels for a week. You can see that I'm in range most of the time, with some excursion into the high level. On the right is my blood sugar for a week during the COVID infection. As you can see, I spent a lot more time "out of range" and in the high and very high levels. I was finding that the only time my blood sugars were in range was when I was asleep. I am on insulin and it didn't really seem to be doing anything - I dread to think what my levels would have got to had I not been on insulin! Safe to say, I was relieved when the infection passed and my blood sugar levels returned to "normal".

I'm over in the UK and understand that the measurements are different in the US. For reference, (I think that) 3.9mmol/l = 70mg/dl, 10mmol/l = 180mg/dl, 13.3mmol/l = 252mg/dl.

Would love hear anyone else's experiences with this!

  1. Hi . It is frightening to think what might have happened had you not been diagnosed and on treatment before you were infected with COVID, especially considered your struggles to get your specific type of diabetes accurate diagnosed and get on the right treatment. The inflammation caused by COVID can worsen insulin resistance and drive blood sugar levels higher. In turn, high blood sugar levels make it harder to fight off infection. It's possible that COVID is still having that impact on you. Have you talked with your doctor about it? Do you adjust your insulin dose to make up for the higher levels? Here is an article from one of health writers about her experiences with illness and blood sugar levels that you might find interesting: https://type2diabetes.com/living/fighting-cold. I hope others in the community chime in. I would be interested to hear how they are impacted by viruses. I hope you are improving overall and that you kick this thing soon. Lots of gentle hugs. - Lori (Team Member)

    1. That might have been the trouble with that particular author's numbers. With any testing device, it's important to "get to know it." For instance, I have learned over time that our forehead thermometer measures about a degree lower that it should. So, I know that if someone in the family has a temperature of 99 degrees, it's really about 100 degrees. I am glad your numbers came down quickly, but I would never fear that you are overreating if you call your doctor or go to the doctor when illness drives up your numbers. Our former high school principal lost both legs from the knees down, one hand and several fingers on one hand to COVID and type 1 diabetes. He was unvaccinated and it was early in the pandemic when treatment was not as good and the virus was more potent, but his situation is evidence that caution and erring on the side of safety is a good thing. Thanks for creating a forum about such an important topic. Best wishes. - Lori (Team Member)

    2. , that's interesting because our forehead thermometer also reads a bit low! Speaking of low - I seem to have found a solution for the CGM reading lower than it should during its first week. I read online about "insertion trauma" and CGMs. Apparently in some people the body notices that this foreign object has been inserted and goes to investigate, and this can throw off the CGM as it's warming up. I'm sure there's a more technical way to explain that 😅 Anyway, I've started applying the CGM 24 hours before I scan/activate it, so my body's got a whole day to get used to this thing being in my arm. So there's a day where I'm wearing two CGMs - one on its last day and the other "warming up". Then the next day I activate the new one. It's made such a huge difference to the accuracy! I actually can't believe it. And I still get the full 14 (now 15) days wear out of each censor. Maybe that will help someone else who's having an issue with the accuracy of theirs.

      Thank you for the encouraging words about contacting my doctor and not worrying that I'm overreacting. I do sometimes think that doctors are so busy and I don't want to bother them. Gosh, that's awful about your former high school principal 😢 What a traumatic thing to go through. The pandemic was a really awful time for so many people. It's definitely better to be safe than sorry when it comes to our health!

  2. Hi . How cool that you figured out the GMC thing. I'd never heard of insertion trauma. I'll have to remember to share your reply when others have similar issues. Thanks! - Lori (Team Member)

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