What should my fasting and normal blood sugar be?

I have type 1 diabetes. What should my blood sugar be when I wake up in the morning (fasting) and before meals? What about after meals? My doctor says one thing, I’ve read different things online. It’s all very confusing! Does anyone know exactly what the numbers should be? Thanks!

There is no “exactly what the numbers should be”. There are varying degrees of probably better or of almost certainly bad long term.

Start by describing some of what you think you’ve been told so that people have something more specific to respond to. Open ended questions about diabetes are … well, there is a reason the phrase “your mileage may vary” pops up so often in this context.

It also helps to know something about how you are treating your T1. If nothing else it helps provide some context to put your questions in.

Love the handle John.

Yes indeed, the short answer is there is no exact answer. Normal (healthy person) BG is 70 to 100. I’m not su hat you have been reading online, but “Blood Sugar 101” really helped me to understand how it all works and what I might expect.

Well, let’s see if I can’t elaborate on that. Um, my doctor says I should strive for 70-130 fasting, and 180 after meals. I’ve read several articles online that said 180 after meals is way too high, and you should shoot for anything under 140. It’s all confusing because I don’t know who to believe. If tight glucose control is the name of the game, then how can my doctor be right about that 180 after meals? Wouldn’t that be dangerously high? I need to know how to dose my meal-time insulin to achieve goal numbers, at least after meals. Is my doctor right about 180 after meals? I hear so many people online say they keep their blood glucose at 80 all the time. How do they do THAT?! That must be some powerful insulin they’re taking! Or, maybe I’m not taking enough? And Afrezza users on Twitter – they’re really hitting their marks! But, then I just read one discussion on this forum whose blood glucose hit the roof on Afrezza! I’m more confused than ever! Any advice? Thanks in advance!

Oh, is Blood Sugar 101 a book? Who’s it by? I’ll look into it; thanks!

It’s both here’s a link to the Website.

I think it’s more useful to speak of it as a target range, and I don’t think it’s going to end up being the same for all T1s. Mine is 100-140 for instance. There are also target BG’s for calculating correction boluses for pump users or people on MDI. You actually enter it into your insulin pump settings, if you have one, and it can change throughout the day (mine does).

Dexcom CGM default threshold for a low BG alert is 80, so I think that’s pretty extreme. For my part I definitely sense a low at that level and if I had to stay there all the time I’d feel like sh*t all day, so good for them if that’s what they shoot for but it’s definitely not a universal rule.

Re Afrezza, I don’t have any experience but recent posts and a live chat here on TUD certainly aroused my interest. I think a lot of us are just starting to learn about it. There was a great live chat about it here on TUD a couple weeks back. I assume it’s archived somewhere–you might poke around or ask one of the Admins.

On edit: that 100-140 target range does NOT mean I’m always successful, and after getting a CGM I find I’ve actually been hitting up near 190-200 after some meals without (previous to CGM) knowing it. Not sure I’m all that freaked about it though as long as it’s back in range within a few hours. I’ve had T1 for 31 years with no complications so I may be more sanguine about these BG vagaries than some…

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About 3 months ago my BG meter thought I was at 582. So I’m awaiting death which I expect will overtake me any moment now. I only hope I have time to finish this post … :skull: :smirk:

What’s bad about high BG is when it is consistently high over a (long) period of time. So what I assume your doctor is advising you to do is to attempt to keep things closer to the normalish range of things if you can. I expect @Terry4 to pop in here at any time with a comment about “time in range”.

But even with that as a loose general guideline it’s important to remember that people and their treatments differ. The most important thing in my opinion to remember about “the numbers” is to try to not let them drive you crazy. :anguished:

In all fairness, MY numbers don’t drive ME crazy, but they have driven my doctor crazy (at times!). I’m perfectly happy with MY numbers, but for some strange reason, no matter how good they are (for the most part), the complications only seem to be getting worse. I was diagnosed with active bleeding (retinopathy) about 8 years ago – and every month, no matter how good I’ve been, it gets worse. The spot in the middle of my right eye gets bigger and bigger, and I see less and less out of that eye. And, there’s NO way I’m getting a needle stuck in my eye, so … there you go. I thought if my BG was spot on for the last 8 years, the bleeding would stop; but that hasn’t been the case. What good is tight control if the complications only get worse? I wonder if things would have been different if I had been better from the very start (it’s been 15 years). Oh, well. Good thing we have two eyes! (Not that the other one’s any better!) It just goes to show, an ounce of prevention beats a pound of cure!

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Um, just out of curiosity, why DID your meter think you were at death’s door? It’s funny you should mention that – last night from out of nowhere, I had the craziest dream. I looked down at my meter and saw 575! It’s never been that high! Not even when I was first diagnosed! Not even when I was DKA (twice!). I guess I was so distraught about coming here to ask this question, I dreamed about it! Heh! SOME “sweet” life, eh?

It read that high because my BG was somewhere in the vicinity of that number.

I use an insulin pump. Earlier that day I had disconnected to shower. Apparently when I reconnected I didn’t get the fit right. I had inserted that infusion set behind me so I was working mostly from touch. When my numbers kept going high even after correction boluses, I reconnected to my infusion set, correction bolused again, and then my numbers (eventually) came back down.

It happens, at least for me.

How high was I really? I do not know of course. The thing most of us forget about our BG meters is that they are never completely accurate. There is always some amount of error. Also the possible error increases when you are relatively far from the “normal” range of numbers the BG meter is expected to encounter. In other words, when you are at the extremes the BG meter number doesn’t really mean too much other than “you are very low” or “you are very high”.

But it is a digital number staring us right in the face. So, being human, we treat it as though it actually is spot on. People will post that their BG dropped to 29 as though that number is anything other than a euphemism for “Oh ■■■■!”

What ya gonna do? :relaxed:

WOW! I wouldn’t “strive” for 180. I’d strive for around 140 or less. 180, IMO is not good enough to protect one from long term complications, if it’s exceeded with any frequency.

I think the 180 recommendation is due to old-school thinking when there wasn’t good insulins availiable (pre-“rapid” days), or meters. Using a pump, (CGM can help, too), eating PROPERLY, and frequent testing should allow a T1 to not keep hitting 180+ after meals. Anyone who says they can’t do that, simply hasn’t yet got all the tools working to their advantage, or they aren’t eating properly. The average T1 needs to AVOID excess carb consumption if they find they can’t prevent 180+ excursions after most meals. It’s all about mindset. Think of the “pay me now or pay me later” ad that ran years ago for Fraam oil filters. We can either control our bgs properly now, or we will definitely pay the price in the future.

When I first got the CGM (just a month ago) and I was still on R and N insulins, I was truly dismayed to discover that my blood sugar was rising to upper 200’s and low 300’s after EVERY meal…and I still had an A1c of 6.8 :stuck_out_tongue_winking_eye: After I changed over to Lantus and Humalog, I found that I rarely go over 200 ever…but still do sometimes at the end of a lantus cycle (I take two lantus injections 12 hours apart.) I have multiple hormonal considerations that impact this, I suspect.

I “aim” for a high of 140 and a fasting between 95 and 120, and I have about 75% success on the new system.

My new naturopath recently tried to put the “fear of God” into me about long term complications after 30 years (I am 32 years with T1) and strongly recommended I go lower carbs to keep my numbers below 130 to prevent complications…then she did lab work and was VERY surprised to discover my kidneys are still very healthy, my liver is still very healthy, and my blood chemistry is still very healthy…even with the obviously very poor control I’ve had for most of my life with T1. I give full credit to the support I give my body with nutrient dense foods and supplements.

I can just barely wait to see how healthy and vital I become now that I am maintaining better control. I am learning to be satisfied with “better control” on a continuum than putting pressure on myself to maintain perfect control. :wink:

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That’s why I think it’s weird even today both my doctor and the ADA still think 180 2 hours after meals is acceptable. Ugh! I think 140 2 hours after meals is a better target; which I normally hit, sometimes even less depending on what I eat. I eat very low carb – works wonders. Just wondering, given all the advances, why my doctor (and many other doctors) and the ADA still believe in the 180? Oh, well.

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Just out of curiosity, how does having such a high number (whatever it actually turned out to be) feel like? Did you go through the whole peeing like a racehorse phase? I ask because sometimes I can go as high as 300 when I’m stressed out or when my hormones go crazy, and the funny thing is, even at 300, I’m not terribly thirsty nor do I have to pee like mad. Do you suppose we type 1’s get accustomed to it after so many years? My A1c is 6% so my numbers are normally very good, but I’ve heard some type 1’s say they have to pee buckets when they hit the 180 mark – wondering what YOU felt like at almost 600?

Blood sugar numbers are part of a spectrum. They do not become “bad” at a certain discrete level, say 140 mg/dl. Non-diabetics may often experience 140 mg/dl without any undue harm. We each have our unique biology and genetic makeup. In that, we do not have a switch that gets flipped when sugar is too high.

In general, high blood sugar for extended periods has been shown to be detrimental for long term health. Just exactly how high and for how long it will hurt you is an individual thing. What I’m trying to say is that there are no absolutes.

What you can do is try to slant the odds more in your favor for the best long-term outcome chance for you. I see 140 mg/dl as the upper end of what I consider acceptable. More importantly I target 65-120 mg/dl as the range I seek to be in for at least 80% of the time on my continuous glucose monitor. I think this time in range (TIR) is a better indicator of blood sugar control than is a BG average or an A1c. Averages can conceal many hypo- and hyper-excursions that are not good for you.

I believe that if you can stay 80% of TIR, then you’ll be enhancing your chances of remaining complication-free or keeping any complications relatively mild. Again, you may better your chances of favorable outcomes, not insure them! There are no guarantees in this life, except for death and taxes.


If you are hitting 140 at 2 hours after the meal and not going low at 4 hours after the meal, then you are doing fine. Recognize that you are doing low carb. A normal “balanced” meal might have you with a 60 - 90 point rise at 2 - 3 hours post-prandial. At the end of 4 hours, when the insulin is most likely out of your system, I would hope to be pretty close to where I started from. Yes, where you started from is also important. Did you begin the meal @ 100 and you had a 40 point rise, or did you begin @ 120 and have a 20 point rise; 80 and have a 60 point rise?

I have been discovering with the help of my CGM that the “tail” of activity for insulin is pretty strong in me and I get some pretty rapid lowering of my BG in the last hour. 140 @ 2 hours post-prandial can frequently lead to a hypo @ 4 hours.

Sadly, this is just one of the frustrating unknowables with this damned disease. For some of us, complications are going to occur, period. They might have been worse or happened earlier if tight control wasn’t there.

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The whole concept of a fasting blood sugar is a bit abstract to begin with. Most people (even non-D) will find that their BG rises in the morning, from the time they wake up until a half-hour or an hour later. The body’s liver dumps sugar into the bloodstream to give you energy to start the day; it’s a normal part of non-diabetes biology.

So is the “fasting” BG before or after the “liver-dump”? I don’t think there’s really a way to define it, or to know what’s causing a morning rise. The best way is probably with a CGM overnight. But, I even find that, first thing in the morning, my fingersticks are inaccurate and my CGM is more reliable (I have reason to believe this, but that’s beyond the topic of this post) – my rationale is that my extremities (arms, fingertips) have been dormant for hours, yet my CGM is closer to where the blood circulation is. So if you’re testing your BG from your fingertips as soon as you wake up, is it even a valid BG reading? My own personal experience would suggest that it is not.

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I think this is very true and often not recognized by doctors or patients enough, BG variation will effect people differently. My BG problems are more of a rollercoaster issue, I don’t stay high (although that is slowly changing) and my A1c is ok due to reactive lows. But I was developing side effects anyway, neuropathy in my feet (itching, numbness and finally some pain), polyuria (especially bothersome at night), difficulty maintaining a healthy weight…Another reason this disease is so difficult to treat and why we as patients need to educate ourselves, “experiment” on ourselves, and hopefully find a doctor who will work with us and allow us to be open to trying different treatments and lifestyle adjustments. There are people who have had diabetes for many years with little long term effects and those whose bodies for what ever reason can’t handle the highs and lows.

Fasting BG is a moving target for me. Here are two fasting tests taken 37 min apart. The first test was taken about 15 min after getting up this morning. My BG goes up like a rocket as soon as my feet hit the floor…I also gave myself a bolus after the first test but as you can see my insulin is so slow that there is no way it will stop the spike…:frowning: I also will not eat until my BG is back in my target range (between 70-140 mg/dL), every day is a new adventure and I never know when the Bete’s is going to show me who the real boss is!!

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