What is normal BG while sleeping?

I’ve been trying to find out what a “normal” blood glucose level is while people sleep? Does it normally go down in non-diabetics because there’s no need for glucose while resting or should it stay in the 80s?

Non-diabetic fasting blood sugar is 70-90 mg/dl. Blood sugar in non-diabetics (I do not call them normal because that implies that I am abnormal)rarely goes below 70 mg/dl because they have a complex counter regulatory mechanism that reacts to a drop in blood sugar with a release of glucagon. It also rarely goes above 120 because the same mechanism senses the high and releases insulin instantaneously into the blood stream. http://diabeticmediterraneandiet.com/what-is-normal-blood-sugar/

Thanks Clare, I did put normal in quotes for that reason, wasn’t sure how else to phrase it:)

No problem and I did appreciate the quotes. In the chatroom we invented an acronym (PWOD) which is People Without Diabetes. So far that term hasn't caught on yet, but it's what I call them :).

This study produces what is called the ambulatory glucose profile. The graph below shows 14 days of data taken from one glucose normal person considered by the researchers to be representative of the normal population. The 14 days of of data are presented as one "standard day."

The orange line represents the median BG. Half of all BGs are less than this number and half are more. The solid blue lines delineate the 25th and 75th percentile. The dashed green lines represent the 10th and 90th percentile.

As you can see, the gluco-normal person has more tightly controlled BGs at night than during the day. The overall control is nothing short of spectacular! The median is below 100 mg/dl and even the 90th percentile is less than 120 mg/dl. I found it interesting that this normal person has BGs below 70 mg/dl a little more than 5% of the time -- see where the 4-8 a.m. dashed green line, representative of the 10th percentile, dips below 70.

Clare - I've bookmarked that website. It's a nice concise summary of what the numbers mean. Thanks.

It is specatacular, but be careful with the interpretation. The data presented were not included as indicative of the general "gluco-normal" population. This is one individual, which amounts to anecdotal.

And thank you Terry for posting the site for the ambulatory glucose profile. I had it bookmarked as well, but when I went to access it again probably close to a year later, they were requiring my membership number and password. This time I am going to just print it when I get to work so I can refer back to it.

I agree that this one person's BGs may comprise an anecdotal dataset. I suspect that this data is not that far off of the actual statistical dataset but I don't know that.

Here's the actual quote in the study narrative:

Figure 3 shows an AGP from an individual without diabetes and is representative of a normal reference population.2

I am neither a scientist nor a science writer. I wonder what the word "representative" means in this context. Footnote 2 points to this study entitled, "Reference Values for Continuous Glucose Monitoring in Chinese Subjects," published in 2009 in Diabetes Care.

Maybe the AGP researchers found this anecdotal dataset consistent with the data found in the larger study done on 434 Chinese men and woman. Perhaps citing this study elevates this single person data out of the realm of anecdotal. I don't know, but it seems reasonable.

The link in my comment below still allows access to the full study.

I don't know why the link I bookmarked a year ago doesn't allow access anymore ? But I can get in to the one you posted today. In fact I took the statistics to my CDE one day when we were meeting and showed her the 5% below 70mg/dl stat for gluco-normal folks. It has pretty much stopped any warnings about my 5% below 70.

I would give your CDE credit for listening. They don't know everything and they're generally so fearful of serious hypos that they feel better when their patients run their BGs a little higher.

Do you know that hospital personnel have an actual name for this? It's called "permissive hyperglycemia," and ranges up to 180.

Terry I give her a lot of credit. It took 2 years to train them, but now I have both an endo and CDE who leave me to my own devices - dexcom/omnipod :). They still prefer me to run higher than the 85 I have targeted on my pump, but they wouldn't dream of changing the settings.
But CDE's and endos aren't the only ones who are hypophobic. I can't tell you how many PWD I have run into here and elsewhere who also have this almost paralyzing fear.

It took me a long time to appreciate that I’m nowhere near a typical PWD. For a long time I held bad feelings for medical practitioners, but when I think of the typical patient, I realize why they act the way they do.

Some of my past doctors never fully appreciated what I know and I often felt patronized and made to feel like a child. When I took full ownership of my diabetes and did the study needed to manage my BGs well, I let new doctors know fairly quickly that they are not in charge.

I decide what’s what and they definitely report to me, not the other way around. I respect what they know and demand reciprocity. They need to explain their rationale for medical advice and I need to understand it. I don’t do everything they say and I tell them that.

When it comes to moment to moment BG management, they better leave that to me. This is not an area where most practitioners have any depth of knowledge and expect they leave me a wide berth.

Not sure if this is "the" Chinese study referenced, but this graph is from a Chinese study with 434 subjects measured.


In 434 subjects, the daily blood glucose varied from a mean minimum of 76.9 ± 11.3 mg/dl to a mean maximum of 144.2 ± 23.2 mg/dl. The SD of blood glucose was 14.2 ± 5.8 mg/dl. There were no significant differences between men and women for these parameters (Table 1).

That's a ton more variation than from the single individual shown. There are just too many studies out there, now, showing that gluco-normals actually do show a tone more variation in BG than we previously assumed. What they seem to share in common, rather, is the ability to bring BG back down to moderate levels relatively quickly.

There is an important misconception here. The chinese study uses averages the ambulatory glucose profile in contrast uses quartiles like the median.

The disadvantage of averages is that extreme outliers will bias the result. If you want to represent the most likely glucose number the healthy individual has then the average is misleading. Let us assume you want to know the salary to expect as an IT specialist. You then ask 10 professionals in this field and get these numbers:


Now the average is 147300. But is this realistic? Of course not. Instead the 50% quartile also called median is 89000 which is much more in line with what to expect from these numbers.

The ambulatory glucose profile is based on quartiles like the median. Thus it is much smoother than the average number plot of the chinese study. Same data but different representation / interpretation.

It makes sense that the large group has a more variant profile than a single individual. I guess if that's the point you're making, I see its validity.

From a plain English sense of the word "representative," the single person graph certainly does not represent the breadth of the collective but does illustrate that it's a average member of the group.

The OP asked what's normal for a non-diabetic while sleeping. I think the single individual example I offered is normal while the larger cohort better represents the range of normal.

I get your point.

That chart, by the way, does look like one drawn from the second study that I referenced.

To really show the difference here is my ambulatory glucose profile for the last 30 days. These days include one holiday and a massive increase in temperatures. And yes there is room for improvements. The scale is 0 to 250 mg/dl (top line). The green area is from 70 to 140 mg/dl:

I agree that outliers can strongly influence both the mean and the standard deviation. On a sidenote, that's one of the reasons why I don't particularly think standard deviation is adequate at all to measure variation for us.

Anyway, it really does come down to what you mean when you say "healthy" though Holger, and what you mean by "most likely". Even the extreme outliers in the Chinese sample set had normal OGTT numbers, nothing that would indicate they are diabetic anyway. Whether or not a person is "likely" to fall outside of a certain range is exactly what we are discussing.

What I see is a tautology, nothing more really. We'll scrub the data from non-diabetics to best represent ideal BGs and use that to represent "normal". Well, how then do we define normal? Well, we'll define it to mean that your data has to fall within the range of the scrubbed data set.

On another sidenote, yes, for things like salaries, or housing prices, for the reasoning you noted, it is practice to use median because those 7 figure salaries and 8 figure home prices are so far out of the realm of "normal" that they do not even apply to 99.99 percent of the population. The same cannot be said for BG data when 90% of the "normal" population does fall within a much wider range of BGs than it seems like a lot of people are willing to accept, despite the evidence presented by raw data.

Regarding the manner in which the two datasets in question are treated you have an excellent point. However, you still wouldn't compare a single indivudal to an entire dataset regardless.

In fact, the use of all the statistical analysis for teh single indvidual, regardless of how you treat the data is just plain ol' psuedo-replication.

Hi Holger! Wow, your software has really advanced. I'm guessing that the yellow region is the 25th to 75th percentile and the dashed lines the 10th to 90th percentile. Is that right?

I love the way the AGP makes it visually apparent where you need place your control efforts. It appears that you have moderate BG low challenges in the noon to 17:00 time frame. I wonder if eliminating those lows might help with your evening highs.

Have you found the AGP to be a helpful tool in managing your BGs? What does your 14-day profile look like? If you don't mind me asking. All in all, this profile doesn't look too bad for a T1D!

Would you mind sharing, again, how I can access this software?