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Let’s just get straight to the point, blood sugar fluctuations are normal for everyone, even people who do not have diabetes.
Sure, in a perfect world our blood sugar levels would stay a constant 100 mg/dL (6.1 mmol/L) at all times, but in a real life situation that is completely unrealistic.
Blood sugar levels can fluctuate from day to day, from hour to hour and even from minute to minute – this is all normal!
Blood sugar fluctuations can occur for a variety of reasons, some of which we have more control over than others. And of course, large fluctuations could be a concern.
So let’s talk about normal blood sugar levels, how much of a fluctuation to expect, and what you can do to regulate your levels a bit more.
Normal Blood Sugar Range
Let’s do a quick recap of normal numbers.
Fasting blood sugar:
- Between 70-100 mg/dL or 4-5.6 mmol/l (optimal)
- 70-110 mg/dL or 4-6 mmol/l (still good control)
- 70-130 mg/dL or 4-7.2 mmol/l (more liberal, but realistic for many)
Postprandial blood sugar (2 hours after a meal):
- Under 140 mg/dL or 7.8 mmol/L
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What Causes Blood Sugar Fluctuations?
Events you have control over
Events that cause blood sugar fluctuations that you typically have control over include:
- what you eat
- when you exercise
- remembering to take medication as prescribed
Events you may have no control over
On the other hand, some events may be out of your control, such as:
- physical and emotional stress
- fighting a cold or infection
- some medications
Still, there’s a huge difference between normal blood sugar fluctuations and having poor control over your diabetes.
How Much Of A Fluctuation Is Normal?
This is a bit of a loaded question, as it can depend on many factors and it also depends on the person.
As an example, fasting blood sugar that bounces between 80 mg/dL (4.4 mmol/l) and 110 mg/dL (6.1 mmol/l) is pretty normal – those values are still considered “within range.”
Another normal fluctuation example would be if your blood sugar was 6.4 mg/dL one afternoon, and then a few hours later your blood sugar was 6.9 mg/dL.
What’s not necessarily normal is if your blood sugar is 75 mg/dL (4.2 mmol/l) one morning, and then 140 mg/dL (7.8 mmol/l) the next morning – that’s a large fluctuation!
The only way to know your sugar level is to check, and check often!
You may check your blood sugar before breakfast and find it’s 95 mg/dL (5.3 mmol/l), but that doesn’t mean your blood sugar is going to stay at that level all day.
Ideally you want to be working toward having a blood sugar level that is within a healthy range on a consistent basis.
Fasting blood sugar:
- Between 70-100 mg/dL or 4-5.6 mmol/l (optimal)
- 70-110 mg/dL or 4-6 mmol/l (still good control)
- 70-130 mg/dL or 4-7.2 mmol/l (more liberal, but realistic for many)
Postprandial blood sugar (2 hours after a meal):
- Under 140 mg/dL or 7.8 mmol/L
The more consistent your blood sugar is on a daily basis, the better off you are. Throughout the day your levels may vary around 20-30 mg/dL (1.1 -1.7 mmol/l) naturally; your goal is to stay within range as much as possible.
A1c versus Blood Sugar
We often get asked if it’s necessary to check your blood sugar if your A1c is within range.
First, review the following guidelines for hemoglobin A1C:
- Under 6% optimal
- 6-6.5% prediabetes
- >6.5% diabetes (>8% poorly controlled diabetes)
If you’ve been diagnosed with diabetes it’s always recommended to check your blood sugar levels, even if it seems everything is status quo with your A1c. A1c and daily blood sugar checks measure different aspects of your diabetes control, but both are important for having good control.
Checking blood sugar daily catches small fluctuations; your A1c level does not catch these smaller fluctuations because A1c is an average.
A1c won’t tell you if your blood sugar is rising a bit mid-morning, or dropping low in the afternoon. A1c represents what your average blood sugar has been over the past 3 months; you could have a relatively good A1c and still be having a lot of fluctuations throughout the day.
Checking your blood sugar with your meter is the best way to monitor blood sugar trends and know your day to day fluctuations.
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How Often To Check Your Blood Sugar Levels?
Most diabetes organizations recommend checking your blood sugar 3-4 times per day.
Many people choose to check before breakfast, midday, and then before bed, although your doctor may be able to suggest specific times that are best for you to check.
If you have poorly controlled diabetes, then you may need to check more often until your control improves. Checking more frequently (5-6 times per day) will better allow you to remedy your high blood sugar.
How To Minimize Blood Sugar Fluctuations?
Remember, even if you ate nothing all day your blood sugar would still go a little up and a little down throughout the day. This has to do with hormonal changes that you don’t even realize are happening.
But, there are a few things you can do to improve your control and minimize fluctuations.
1. Eat Consistently
When we say eat consistently, we don’t mean eat all day. We mean eat a healthy diet day in and day out.
You don’t need to (nor should you) eat the same exact thing every day, but it is beneficial when you can eat the same types of foods and keep your carb intake consistent, and for many people, they need to lower their carbohydrate intake.
Carbs are the nutrient that has the greatest impact on blood sugar levels.
Many of our members find consuming between 50-80 grams of carbs per day results in optimal blood sugar control.
Subscribing to our meal plans may be helpful to you if you are looking for more structure and guidance when it comes to eating consistently.
2. Check Often
As stated above, checking your blood sugar is the only way to know what your blood sugar is. Plus, that number changes so frequently, which is why it’s important to check often.
If you have trouble remembering to check your blood sugar try setting an alarm on your cell phone and keeping your meter in a frequently visited location.
You can also use a method called “monitoring in pairs” – this will help you determine the effect of different foods/ meals on your blood sugar levels.
View the image below to see how to do this:
3. Record Your Numbers In A Log
Don’t just check your numbers! Keep a log of your numbers. 🙂
Writing down your blood sugar levels can help you, and your doctor, identify trends in your fluctuations. It’s especially helpful when you can also log your food intake and exercise routine alongside your blood sugar levels.
By looking at several days worth of blood sugar values you can better identify patterns. For example, you may notice certain foods are more problematic on your blood sugar than others.
Logging your levels is a great way to understand your body and your blood sugar levels, and how things in your life influence you – food, exercise, stress, sleep, medications, etc.
Blood Sugar Fluctuations Q&A
Below are a few more questions we commonly receive about blood sugar fluctuations.
Can the menstrual cycle cause blood sugar fluctuations?
Yes. Hormone changes that occur during your menstrual cycle impact the same hormones that regulate your blood sugar.
Each woman will respond differently during their menstrual cycle so make sure to check frequently so that you can respond accordingly.
How do you feel when your blood sugar is high?
Signs and symptoms of high blood sugar include:
- Thirst
- Fatigue
- Frequent Urination
Depending on on how your blood sugar level is, you may not notice any of the above symptoms.
The best way to know if you’re high is to check your blood sugar. If the reading seems to be a “sudden high” make sure to recheck your blood sugar to confirm that your blood sugar is truly elevated – on occasion your meter could give you a false reading.
Can drinking water lower blood sugar levels?
If you experience a high blood sugar reading you should drink water as high blood sugar can make you dehydrated. Water doesn’t directly lower blood sugar, but it can help dilute your blood which would temporarily fix your high blood sugar.
You should also avoid eating anything until your sugar level returns to an acceptable range. Contact your doctor if your blood sugar is above 400 mg/dL (22.2 mmol/l).
Conclusion
It is normal for blood sugar levels to fluctuate and it is dependant on many factors.
Stay focused on the things you can control, such as diet, exercise, and medication.
Acknowledge that some fluctuations will still occur regardless, but in general those are small fluctuations that won’t disrupt your overall blood sugar control.
Of course, if your levels are always high then you need to be proactive. But if you are keeping your levels in range, that’s a good thing!
The important thing is to monitor regularly so you can recognize patterns and take action on any major blood sugar fluctuations.
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Hello,
I underwent prolonged stress from November 2021 till June 2024 (high). The last blood test I took was in august 2021 where everything was normal.
The recent blood test I took in august 2024 (2 months ago) I had an A1C of 6.1 and a fasting glucose of 102.
Usually, my diet has always been good incorporating lentils, quinoa (sometimes white rice), millet, black beans, refried beans, salads, egg whites/regular eggs, eating bread in low quantities, paneer, vegetables, smoothies (no protein powder), low amounts of alcohol (less than 5 drinks a month), tea everyday twice with a sprinkle of sugar (total 1-2 teaspoons and 2-3 cookies small in size daily, ice cream (less than 2 times a month), green tea less than 5 times a month, and occasionally cereal (3-4 times a month). I have been doing HIIT exercises (Orange theory fitness) for exactly 5 years now and have been going 3 times per week for a total of (180 minutes per week) and am 31 years old. I used to eat dinner at 8-8:45PM for years.
After the blood test I increased my physical activity by including walking 30 minutes post dinner and doing low intensity yoga 3 times a week. I now eat dinner between 7-7:30. I stopped cereal and cookies and only put very little sugar in tea. I reduced ice cream and alcohol levels as well. I increased green tea and no longer facing prolonged stress. I have been checking fasting glucose levels since September 1, 2024 and it seems to fluctuate anywhere from 91-103 daily. I measure usually at the same time. I have also increased water intake.
My main question is will glucose levels stabilize?
Fluctuations are normal for everyone, blood glucose never stays at one level. For fasting under 100 is normal so you’re pretty close to that. Keep at it.
It is too much for me to take my blood pressure many times a day I take it every 4 to 5 days otherwise it stresses me out I’ve been checking only every 4 or 5 days it gives me te apropriate results still right ???
The information in this article is related to blood sugar not blood pressure. Most people test blood sugar levels once or twice a day or a number of times per week. Blood pressure can be taken less frequently, even once a week is fine. Keep an eye on patterns in your numbers to make assessments on what to do. Hope that helps!
This article was very helpful. I was recently diagnosed as pre-diabetic. I acquired a mentor and check my levels often. I get a lot of fluctuations during the day. My levels stay between 50-150 per day. I didn’t know if this was normal or not, until I read your article. Thank for the insight.
Fluctuations are normal, and with a few tweaks you can aim to tighten your range a bit (aim for between 70-140mg/dL.) If you’re frequently dropping to 50mg/dL, I would recommend throwing an extra snack into your day to keep your eating patterns more consistent and hopefully prevent those lows. Great work!
One day I felt very tired and took my blood sugar after eating a small meal and it was 4.0 and then the next morning my fasting blood sugar was 6.8.
What could cause such a change?
You may find this info on morning blood sugar helpful Mark.
Fyi As I type 1 diabetic and a regular at the gym. I can tell you depending on what your doing your number will differ. Cardio will lower your blood sugar while muscle/strength training makes the number go up. It’s best to check your number before working out. Do muscle training only when your number is low enough and cardio on the opposite days. Unfortunately we have to accommodate this disease. As As type 1 diabetic going on 37 years I understand your frustration. Good luck and thank you for your service.
After seeing a naturopath I have adjusted my supplements and eliminated, to the best of my ability, wheat and other grain products. In just over 2 weeks I’ve seen a vast improvement in my daily numbers, from being frequently in the red zone to now mostly green and occasional yellow (using Libre2). I am striving to get them lower of course. Up to now, my fasting numbers were typically between 170-200. This morning (5:15 am), my fasting glucose was 116, which is exceptional for me. However, after having just a few sips of water, doing some journaling, and having a bowel movement, it jumped to 172 in just over an hour, then 178 about 20 minutes later. I’m used to fluctuations during the day but that seems like a large jump. I am not on any prescription meds, just taking Berberine and other vitamins. Similarly, last evening, it went from 196 (less than 2 hours after eating chicken and salad) down to 122 in less than an hour.
Can having a vaccine shot cause fasting am blood sugars to go up? My FBS were doing well until I had the shot about a week ago and now they are running 140-150?
Yes because the vaccine can cause a type of immune response. Things should settle down again soon.
Hey, how are you doing?
Is it normal to eat a meal and 2 hours later your blood sugar is at a fasting rate of 90 reading?
Normal blood sugar after a meal is under 140. Depending what you ate, 90 is perhaps not so unusual and certainly nothing to be concerned about.
I have a question that’s been plaguing me ever since I became a diabetic in 2016 but to the Whipple Surgery. Question: is a Whipple Diabetic different from a normal diabetic? I have had different answers from professionals.
Hi Shirley, I’m not overly familiar with whipple surgery, however, it is a procedure that can lead to a person being at higher risk for getting diabetes. The diabetes however is diabetes, though the way you manage it in terms of your individual procedure and current health, should be discussed with your healthcare team.
Hi Jedha, just came across your website a while ago. Thank you for all the information on your site. I’m really interested to learn more about how to manage my blood sugar by registering for your membership class posted on your site, which I plan to do next month. With all your credentials, and your vast knowledge of type 2 diabetes, I can say that I’m pleased, and can be at peace now. I read your articles, and research that you did on type 2 diabetes, it is very informative, and clear, no big grammar for a person like me, who does not understand the medical terms of this all. I am so blessed to have come across your site, thank you again. How can I send email, or contact you with questions/issues, and concerns. Thank you very much.
Christiana
HI Christiana, thanks for your kind words and we look forward to having you as a member if you wish to join us. For any questions, please contact our help desk: https://diabetesmealplans.zendesk.com/hc/en-us/requests/new
Hi there,
I have an answered question for a long time now. I have mildly diabetic type II. I took metformin after dinner once a day at around 7 pm. Early in the morning, when I get up from bed and took a blood sugar reading it is typically around say 6 mmol/L. But after I wash up and move around for a while without eating anything, my reading can go up to around 6.8-7.2. What is your explanation for this? Is there an explanation beside dawn syndrome? Thank you.
This can be normal Henry. Your liver will produce glucose even when you don’t eat and exercise can stimulate hormones like cortisol that also raise blood sugar levels.
every morning I checked my meter and it always gave me 111, 116, 99, 117. When I went to VA to check my a1c it gave me 7.4. I am surprised and shocked because it suppose to be at 5.4 or 6.0 but it said 7.4. Im so confused now. I exercise every morning and weight train always. Lost 23 lbs in a matter of 2 months and control my eating for over 3 months. Why is it?
Do you check your blood sugar at any other time of the day? If not, I would highly encourage you to start doing so. You A1c captures all your blood sugars throughout the day, meaning that even though your morning level is good, it sounds like your blood sugar may be rising higher after meals. Start by keeping a log of what you eat and blood sugars prior to and 2 hours after a meal. This can help you identify patterns and give you a starting place for making changes.
Respected mam, I’m a diabetes patient. Suffering from last-2003. At this lockdown period I check my blood sugar regularly (4 times per day from last My ay’2020. I look that my my blood sugar levels are fluctuations. I can’t understand why is it. Also I take my food several times in s day. I will be very happy if you give me a good advice about this matter (fluctuation of blood sugar everyday).
Hi Subhasis, read the information above. As it explains, fluctuations are normal and to be expected because daily levels are influenced by many things. Overall you want to aim for levels in a healthy range.
Ella 1/2/19 I appreciate the info about the fluctuations in blood sugar,am going through that and I think I haven’t been eating enough and timely,cause this morning it was 165 ,it haven’t been that.but I do also have a cold am dealing with so I will work on those to things. the Dr just took me off insulin and junvia. I just do Berberine 3 a day with each meal.
A cold can absolutely impact numbers! Just focus on getting better- lots of fluids and rest. Feel better soon.
As a Metformin Type 2 for 8 years I now occasionally use a Libre Freestyle Continuous Glucose Monitor to see how various diet changes etc affect me. What has been very interesting is that while sleeping the level is relatively low and steady – in the 4/5/6s. At about the time I’m waking up my blood sugars rise to the 7s. A blood strip confirms that reading. Can’t decide if the body is breaking down fat to fuel being awake. Using the CGM has made me question whether strip checks before and 2 hours after meals are good indicators. Plotting the CGM values with Excel or the Libre analyses tell a much more nuanced story. The analyses prediction of my six monthly Hba1c has been pretty accurate.
Not everyone wants or needs a CGM John. Overall, any regular check will help you gain better control. But it’s good to hear that the CGM is working well for you.
Just read an article about blood glucose monitors. All monitors whatever brand and model are required to abide by industry standards. The article explained that monitors can flucuate less than or greater than up to 20 points. Thats a lot.
So your monitor isn’t exact in other words.
I took 3 readings with 3 separate strips of course and within a 5 minute period my readings were 170, 154 and 135 respectively.
I bought a second meter to keep my first meter honest and they both will fluctuate in this manor. So, I look at a blood glucose monitor as more of a guesstimate rather than right on the mark.
Indeed they can be different so it is a guestimate but still gives you useful information to work with.
I seemed to have read somewhere recently that blood sugar level machines give figures that are plus or minus 20% accurate. I find this quite shocking. It is possible therefore for my blood sugar to be shown in range when in actual fact I am hypo. Are there more accurate means of measuring blood sugar level. I have been a type 2 diabetic for two years. When I was first diagnosed I came out of hospital; I live in France by the way; taking 5 replaglinide tablets a day and injecting 16 divisions on my insulin syringe. Now I only take 2 tablets a day and inject 12 divisions of insulin. I have followed no particular regime. I have reduced my bread intake, do not have jam or ice cream but will indulge sometimes in one of our local doughnuts. I tell people that I govern my diabeties it does not govern me.
Correct, meters are not 100% accurate, but with that being said they are still the best/only way for us to check our blood sugar levels.
A few things to consider, first, if your meter value does not match your symptoms, then you should always recheck to be safe. Like we just said, a meter isn’t perfect, so it could occasionally give a false reading. Secondly, depending on how your overall control is, you may feel “low” even when you aren’t- this usually happens to people who tend to run very high sugars. (Ex. If your body is “used to” being 250mg/dL, and suddenly you’re 150mg/dL, that can cause you to feel low even when you are not.)
Great work on reducing the break intake! You’ll find the more you’re able to reduce carbs the better off your sugars will be.
I’m trying to establish a routine of monitoring. A few questions:
1– first test of the day — Should fasting be taking first thing in the a.m. even before lemon/acv water and/or after this drink but before eating breakfast…or both?
2– Next– two hours after first (after starting lemon/water drink or 2 hours after starting to eat breakfast
3– Before lunch and 2 hours later
4– Before supper and 2 hours later
5– bedtime.
That adds up to 7 to 8 times a day. Is that excessive and ridiculous or necessary to be knowladegable about what is happening?
I want to keep it simple and doable, but if I’m going to be testing frequently I want to do it in the smartest and most useful way.
Advice is welcome.
Thanks.
Hi Zazie, I think creating a routine is a GREAT idea as it will hold you accountable each and every day. Make sure to find a nice log, or book, or app that will be easily accessible to you.
Like I mentioned in your other post, a true fasting value would be before the drink. Assuming you’re going to drink the ACV, wait 15 minutes, then eat breakfast shortly after, I would suggest checking again 2 hours after your first bite breakfast. (If there will be a long lapse between the drink and when you eat breakfast, then you may consider checking before the drink, before breakfast, and then 2 hours after.) Hope that makes sense!
Seven to eight times per day will be helpful initially to identify trends and allow you to make adjustments. The more data you have, the more you can see what foods/medications/ exercise patterns are working, and which aren’t. Down the road, when you feel stable and have achieved your ideal A1c, then you could certainly consider reducing the number of times you check. (Ex. 4-5 times per day.) Another consideration is cost of checking that many times per day, will insurance cover that many test strips, etc. If it ends up being cost prohibitive to check eight times per day, you can alternate which meals you do the 2 hour mark for.
Thanks for the clarification an quick response. Very helpful.
I’m looking for some guidance and suggestions. My life is fairly routine in that each day is somewhat like the day before. I am retired but have a daughter and 9 year old grandson living with me. The day always starts a 7 and I usually have done a reading by 7:30. I’ve always done this because I usually have coffee with milk before putting grandson on the school bus. Breakfast comes more like 8:30 to 8:45. If I wanted to do a pair of readings around this, what would you suggest the timing should be?
I have always assumed the first reading of the day was a good indicator of what I did yesterday but I have never really found it too useful. Frequently I’m totally baffled by the results. I really want to get away from this routine and start to do pairs of reading as it seems that will really isolate some good and not so good meals.
I totally agree with your comments about small changes in reading being normal. I have experimented down to doing multiple fingers at the same time and even doing the same drop with different strips. A variation of about 10 mg/dl seemed pretty common…………Jim
Hi Jim, to monitor in pairs you take a reading before the meal and then time 2 hours from the first bite of food and take another reading. Taking morning blood sugar is still a good measure because as you make diet adjustments, the number may change. Since you are a member, watch out for an update about the 21 Day Lower Blood Sugar Challenge that we are running in early Feb – we do daily check ins during the challenge so you will understand a lot more after the 21 days.