What does a 5% A1c look like?

I’m posting this out of sheer curiosity. Can those of you who use insulin (Type 1 or 2) and maintain your A1c in the 5% range post one or two days of blood sugar readings? I’ve really ever seen what “day to day” blood sugar levels look like for people who use insulin but have really tight control. If you don’t have a CGM, just post the readings from a meter. If you want to disclose it, I’d also be curious if you eat low-carb or not.

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As you know, I am T2. And I follow a strict very low carb diet. And. Everybody is different. I don’t struggle with some of the problems that others struggle with. I still make some insulin. I try really hard at blood sugar control, correcting when needed and not overcorrecting. And my body doesn’t give me crazy readings (much of the time) so I consider myself lucky. I try to keep my blood sugar “in range” more than striving for an A1c

I’m less organized about writing down records than I used to be… and far less neat. Above the orange line is when I was having trouble with overnight rises due to the other med… below the line I stopped it and went back to Prilosec otc

Sam19, are you left-handed?

No I just have terrible handwriting. It’s the MD DNA

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Last month

Please bear in mind these are just ultra abbreviated cliffs notes… this is just what I look back on to try to see major trends… many tests, surprises, victories, and defeats aren’t shown here


I don’t have a CGM, and rather than post a printout of my spreadsheets, I just counted how many readings in what range for October to date. So far, I’ve taken 65 readings this month.

I eat about 120-150 carbs most days. I have a higher than average response to carbs, with my BG rising between 8 and 10 points per gram of carb within an hour on those occasions I’ve tested with glucose tabs or milk. Since my BG would go too high postprandially if I eat many carbs at one time, I often super-bolus before a meal for the meal itself plus a snack I’ll eat a couple of hours later. That’s the only way I could eat the number of carbs I do without having postprandial highs of 200 or so. I aim for a range of 70-160. Since I don’t often test postprandially, I know that I go higher than is shown most days. I’ve had an A1c of between 5.5 and 5.9 with every full period I was on MDI since going on insulin in May 2013.

Range # readings
50-59 3
60-69 0
70-79 1
80-89 5
90-99 8
100-109 11
110-119 10
120-129 11
130-139 7
140-149 4
150-159 2
160-169 2
170-179 1


For what it’s worth, here are my last 4 days. I’d average about 100g of carbs per day, but this varies a lot from day to day, say 50-150g. Importantly, in a single carb-dominated meal I’d not have more than about 20g of carbs. Unless you have access to non-injectable insulin (which I am still planning to try), it is just impossible to bolus for larger amounts of carbs and maintain non-D bg. Lunch is typically my largest meal, around 30-50g of carbs, but I can do that only in combination with plenty of fat and protein, so a square-wave pre-bolus + normal bolus can take care of it with min spikes. Last night I did spike to 180, and that was more than 3 hours after dinner (sausage + some potato chips + beer). My square wave was apparently too small and too short for the sausages, and I did not pay any attention to my bg (mistake, oh well). For people who have CGM, A1c should be considered totally unnecessary and irrelevant, but they still continue to do that test on me (my last A1c was 4.9).

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Ooh… That graph looks beautiful! \

Can you tell us a little more about your eating model? If a meal is ~20 carbs, what does your meal/snack frequency look like?

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I will show two weeks, but not sure if I can post two photos in one post. Here is week 1 which has some definite highs and lows. Week 2 looks much smoother, but some of that is due to some sensor inaccuracies. I turned it off in the middle of one night when it kept alarming for readings in the 40’s when my BG was in the 90’s. I average 90-100g of carbs per day. Very rare to have a meal with over 30g–usually 20-25g per meal and then snacks. I do not keep track of carbs eaten for low BG’s–usually glucose tabs or fruit. I walk a lot, especially after breakfast and that stops some of the post-meal spikes.

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You have a pretty tight range. Am I reading it right that your upper bound is 130 during the day?

Aaaahhh, reminds me of my written logbooks during my Lantus days!

fasting = 78
9 am = 89
11 am = 92
12 pm = 94
1 pm = 106
3 pm = 112
4 pm = 82
6 pm = 81
8 pm = 96
10 pm = 98
12 am = 109

and then the next day… pretty much the same. LOL

I don’t relate my A1c result to “tight control” since it is not a goal, it is the way I manage my T1. By keeping my bg in normal range the A1c follows, and means more to the chart and other diabetics than it does to me. The rare high and low are managed quickly and without much trouble.

I enjoy a nutritious eating plan, daily exercise, and a happy healthy attitude toward my body, my health, and life. The numbers agree with all this :slight_smile:


Wow, all this information is fascinating to me. Some of you have amazingly tight control. And I know that the A1c isn’t the be-all, end-all, but I cited it because I do think someone with a 5% A1c would have very different numbers than someone with a 7% A1c, so it was an easy way of quickly targeting people with tight control.



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I actually believe that the core difference between an A1c in the 5s and one in the 7s is variability. You really don’t find people achieve an A1c in the 5s unless they get their time in range locked in (like > 75%) and get their SD down. My SD for the graph I showed was 25. You can see @Jim26 also has a good time in range and SD. I bet that is a common theme for anyone with an A1c that tracks these things. For me the key to getting the SD down seems to be low carb, more advanced dosing and timing of mealtime insulin and prompt (and sometimes “preemptive”) corrections.

I agree that time in range is key. I look to where I can string together time periods of time in range (overnight, mornings, evenings)

Overnight - I try not to eat after 7:00.
Mornings - I’m not a breakfast eater, so I can string together time in range.
Afternoons - Try to eat low carb lunch which makes it easier to manage my afternoon time in range.
Evening - can be more adventurous in eating since I can be more aggressive in my insulin usage.

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Here’s a shorter version if you don’t want to wade through all the math:


This is an interesting paper saying, essentially, that A1c depends on personal lifetime of RBCs as well as BG levels. I think they’re right because I concluded the same thing some years ago [grin]. At the time I was using a CGM, which showed I rarely went over 130, but according to my A1c, my average BG was over 130, which meant a lot of readings over that. I asked Bernstein about it, and he said my meter probably read low. That didn’t make sense to me because the meter matched the lab values, and I decided my RBCs probably lived more than 120 days and stopped worrying about it.

Iron increases the production of new RBCs that would be less glycated than old RBCs and I tried an experiment in which I took iron pills for two weeks before my blood draw for A1c. But just my luck, the A1c machine at the hospital where I get A1c measured broke that week and they sent the samples out, meaning different machine with different technicians, so it meant nothing, and I didn’t try it again.

Now there’s evidence that it’s true that variation in lifetime of RBCs can be significant. Two people could have an A1c of 5 and different average BG levels.

I found that meters (and the A1c test) can be confounded by individual variations. In my case, I have polycythemia vera (high hematocrit) and some meters have severe errors when hematocrit is low (anemia) or high as in my case. I found that selecting a meter that had minimal errors over a range of hematocrit improved my correlation between meter readings and A1c. Since getting a CGM in June I found that my last A1c was only 0.1% lower than the A1c predicted from my CGM readings. I’ll have to see if the CGM and A1c continue to track closely.