Max or Lowest High Bg?

What is the bg number that will cause damage and why? Read it was 160. But not sure. Not talking about A1c, but spikes. Thank you.

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I start to freak at 400. But, I’ll be aggravated around 300 - some.

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Personally, I don’t like being over about 150-160. I physically feel effects once I’m in the low to mid 200’s. It is a rare thing for me to hit 300 and when it does, if feels awful.


I think the development of complications can occur at different values for different people. Some people have some genetic protections, so they may able to hit 200 (or 300?) regularly without that causing any trouble. Others may need to stay under 180 or 150 because they don’t have those protections. Unfortunately, we don’t yet have a way of knowing the exact number that begins causing damage for each individual person (as far as I know). Fasting levels and levels between meals likely factor into this is as well.

The ADA recommends keeping post-meal bg below 180 mg/dl, but Joslin Diabetes Center says anything above 160 mg/dl is considered high. There’s a study that measured bg of non-diabetics using cgms for a few weeks, and they generally spiked to 120-140 after meals on average. Of course, some were higher than that though since that’s just an average.


Do you have a reference for it? A link to share?

It’s funny how there are some doctors who say that having an A1C in the 5’s is too low :hushed:. But then they say a BG above 160 is bad!

Um, medical community…you’re not giving us a whole lot of wiggle room there…

I personally ignore all of those recommendations and just try to keep my A1C and BG as low as is manageable. I try for 80. I don’t try to keep it below 70, but I don’t freak if it goes there.


Thanks very much for the info. @Katers87.


Sent from my iPhone

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@Eric2 Wow! 80. That’s great. How do you keep it so low? Do you use a pump?

I do use a pump. But I don’t keep it that low, it is just my target! :grinning:

Of course it goes up and down all the time. But I just don’t target 120 or higher numbers that some endos seem to think is safer. I always try for 80.

As we heard in The Patriot, “Aim small, miss small.”


160 is the number most non-diabetics stay under.

Spiking to 160+ for a short time, and then returning to 80-140 is not likely to cause noticeable damage. The DCCT study from 1980s showed that lowering average BG and spikes, resulting in Lower A1Cs, significantly reduced complications/damage. (Search this site for DCCT and you find many references).

I was diagnosed in 1960s, with over 20 years with relatively poor control due to ‘primitive’ tools by today’s standards. I do have eye complications, but it was 20+ years before they occurred. The first noticeable eye damage was diagnosed after 18 years, but not treated until about 6 years later. Today, they do treatments much sooner, with many more options for treatment.

So it’s not just the number. It’s also the amount of time at or above it, which is approximated by your A1C. I have no problem hitting 160+, as long as it comes down soon after. Today we have many more tools that make this easier to do.


LOL I don’t freak out when it hits the low 40’s either. I simply grab some (if I’m home) Hersheys chocolate poured into about 4-5 oz of milk. If I can’t get to that, skittles or other carbs. Today, thanks to an unusual roller coaster ride from doing extensive yard work, I got to handle 3 or 4 significant lows today. But all well that ends well. Back in my “early” days of dealing with diabetes I’d get so low so fast I WOULD freak, and for good reason–I could literally drop roughly 100 points in FIVE MINUTES. That is not a typo.


I have DKA’d once and my meter just read high. I got food poisoning and couldn’t hold anything down and I was MDI then and afraid to take insulin but was checking every hour. I went from 140 - 220 - to higher than the meter could read in three hours. Cost me a week in the ICU. Got on a pump (OmniPod) and a CGM and dropped my AIC down to 6.0, but became Hypo unaware and could drop as low as 30’s with out feeling it. Had to compromise and let my BG’s get up to 180 and not below 120 for awhile.

20 years type 1 and no complications yet. I think everyone with type 1 is going to experience a few high/low issues every now again the goal is to keep things leveled out the best you can. Learn how your body feels when you going high and bolus and learn your lows and always keep frutcose based candy or glucose tabs in your pocket or purse just in case of a low away from home. Just my $.02 but a lot of great info on this site.


A doctor in the hospital told me 200 and damage begins. Personally I think it depends on how long you are high. If you adjust immediately you should be ok. That is why I test so much Am seriously considering a CGM. Has one years ago that was useless. On Medicare so I think I have a choice of Dexcom or Dexcom ? Any opinions?


Hi @Jane16 I began using a Dexcom 2+ years ago when I was prescribed prednisone for long term use. My bg was so unpredictable with the drug, that I ended up testing 20x/day before the Dexcom. With the Dexcom, even on prednisone, my A1C went from 6.8 to 5.8 in less than a year, and it’s been between 5.8 and 6.1 ever since. I would definitely recommend Dexcom.


Thank you Gracie recently I had one corticosteroid injection and had to play with all my pump settings. Fun. Only lasted a short time. I see my Endo in two weeks and will ask about the Dexcom. I have resisted because I just hate the thought of being attached to another device. But I think I will go ahead if approved. My finger tips are getting bad Also my daughter will feel better.

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I went to a T1D conference in 2010 and attended a presentation where the researcher seemed to imply that damage occured at blood sugar levels of 10 mmol/L (180 mg/dl) and above. I remember her comparing the damage our cells experience to turkey skin crisping up as it cooked.

I keep my CGM target at 8.0 mmol/L (140 mg/dl). Can’t say I never go over that (I do, daily), but I try to keep the excursions as brief and minimized as possible.

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It’s much smaller than a pump, and it’s gairly easy to forget about if you put it on the back of your arm. I actually switched back to MDI after getting the Dexcom. I was able to clearly see a lot of problems I was having that were directly related to using a pump (site problems). I can’t imagine my life without it. It’s made such a huge difference in my level of control. I can’t recommend it enough.

Thank you! The CGMs seem to have come a long way since I first tried one that only lasted 3 days and really only worked for 1 day. Fingers crossed that Medicare will approve.

When I hit that low I start to feel ill