DISCUSSION: Fasting Blood Sugar Levels

Before we dig into this discussion, let’s just do a recap on fasting blood sugar levels – the numbers.

The goal ranges do vary slightly depending on the recommending agency, but generally you’ll see these ranges:

• 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)

So now that we’ve got those numbers straight, let’s review some reader questions regarding fasting blood glucose levels.

If you have your own questions after reading this, just leave your comments below.

Why are my numbers low at night and high in morning?

There are several reasons why your blood sugar may be higher in the morning.  

First, remember that diabetes is a progressive disease in which the hormones produced by the body can become insufficient and lack the ability to compensate for glucose in the bloodstream. On top of this, insulin resistance prevents cells from accepting glucose efficiently.

Now, keep in mind that while your body is physically resting overnight, your mind does not take any breaks – the brain is still very active and so are your organs.

During the night, your hormones are very busy at work restoring and repairing your body from the day and preparing it to wake up. In order to do this, there is a release of a group of hormones around 3-4 am, which provides the energy needed to wake you up — one of the effects of this is glucose in the bloodstream. This is called “Dawn Phenomenon” and drives up sugar levels.

Another possibility is something called “Somogyi Effect.” This is when glucose levels drop super low overnight, which activates your emergency backup system, again triggering hormones and sending messages to the liver and muscles to send sugar into the system, which as a result can bounce them back real high. The Somogyi Effect occurs more often in those taking insulin.

You can read more about the Dawn Phenomenon and Somogyi Effect here.

Furthermore, if you are sleeping poorly or even having intense dreams, this can affect hormones as well.

Finally, sometimes medications that are taken earlier in the day (which were helping you maintain good control) may wear off toward the morning.

When is the best time to take a fasting measure of blood sugar?

It’s best to test your blood sugar right when you get up.

If you make it part of your morning routine, such as after you go to the bathroom or brush your teeth, it’s easier to remember.

Keeping your supplies by your nightstand or in the bathroom or kitchen–wherever you are apt to remember–will help facilitate this.

What is the most reliable way to take a blood sample? Is the side of the finger as good as the palm or elsewhere?

The fingertips are the best place to test and get the most accurate readings.

The reason for this is that they are the best site for the end capillaries.

You can lance anywhere on the fingertip, but I always advise using the sides for 2 reasons:

1. Less nerve endings=less pain!

2. You have 2 sides to every finger (plus your thumbs) so you’re doubling the rotation options leaving your fingers less sore and less likely to build up callouses from poking.

How does fiber affect glucose levels and carb intake? Should I increase fiber intake possibly at night and would it help lower my numbers in the morning?

There are several different types of fibers–and only a few (if any) really help directly with glucose levels.

There are certain fibers that help with cholesterol, certain ones that help with bowel movements and ones that aid in blood sugar regulation. While all fiber is healthy to eat they are not all the same.

Viscous soluble fiber seems to be the only fiber that helps with blood sugar control.

Sources of soluble fiber include psyllium husks and chia seeds, along with artichoke, asparagus, winter squash, Brussels sprouts, broccoli, onion, carrots, blueberries and nuts.

It’s hard to say whether increasing fiber in the evening would help your morning levels because it depends on a lot of factors (what else you’re eating, the type of fiber etc). But it is likely that if you substitute higher fiber foods for lower fiber ones, that is a smart move.

Try to make sure your fiber is coming from non starchy vegetable sources rather than grains/starchy stuff (which will also raise your blood sugar).

What can I eat at night to lower levels in the morning?

There has been one small study that has shown eating 1 ounce (28g) of cheese (which is just 1 slice cheese), along with consuming 2 tablespoons of apple cider vinegar (mixed with water) before bed, may help lower blood sugar levels by 4-6%.

Other than that, there is nothing specific you can eat that will lower your blood sugar levels. 

However, you can replace higher carb meals for lower carb meals. You can exercise regularly. You can manage your stress and take measures to ensure you are sleeping soundly.

All of these can help reduce the glucose load on the pancreas and make cells more sensitive to insulin, which will have the effect of lower morning levels also. The tighter control you gain on an everyday basis, the better.

I swim 2 kilometres (1.2 miles) every morning, 6 days a week. I have taken blood sugar readings on waking and it’s around 6.2 (111). When I return from swimming the reading is 6.8 (122). Why? Most waking hours my blood sugar is between 4.0-6.0 (72-108). I only have higher readings in the morning. Any official fasting blood tests have been performed in the morning after swimming. Should I take my next fasting blood test a couple of hours later? Would appreciate any suggestions on reducing my waking blood sugar.

Kudos on the exercise!

My first question is whether you eat breakfast before your morning workouts? If the answer is no, this would not be a good route to take.

It is important for your body to have sufficient fuel, especially with your routine. Inadequate energy for fuel sends stress signals to the body which tends to raise glucose.

The next question is the intensity of your workouts–if they are very intense, adrenaline gets released and this will elevate glucose.

An interesting experiment would be to test before and after a light, moderate and intense workout to see if the intensity is what’s causing a rise in levels.

Another experiment would be to play around with your breakfast beforehand, first ensuring you are eating breakfast, then perhaps altering what you eat to include more or less healthy carbs and protein.

My blood sugar is always high in the morning. Any help?

See above for some of the various causes for high fasting levels.

It is difficult to know what is causing them as there are so many factors to consider – diet, sleep, stress, exercise, along with your body’s own individual metabolic state.

If you’re really struggling, I would encourage you to meet with a Diabetes Educator or physician you trust to discuss your particular situation. They may suggested alterations of your medications or timing.

But just to recap – maintaining a healthy weight, regular physical activity and a balanced low carb diet are some of the best lifestyle habits to embrace to get these levels under control and prevent/ delay diabetes progression.

What do I do if fasting numbers are higher than the night before?

Again I would suggest discussing your particular situation with a trusted professional. It depends on how much higher they are than the previous night…and how high they were at night.

For example, if they are 250 (13.8) in the morning, but 170 (9.4) the night before — then both of those numbers need to be addressed, as they are both higher than normal.

On the other hand, if they are in range the night before but elevated in the morning, there are various options to explore, most of which have already been mentioned above.

But again, it will always depend on many factors — if you wake up with 140s (7.8s), that is much different than waking up with 350s (19s).

The best advice is to focus on the proper lifestyle changes (see above and throughout our blog!) and seek medical help for the rest.

Please pin, tweet or share this discussion and get others involved in the conversations. Thanks. 🙂

And if you have questions of your own, leave them below and I’d be happy to answer them.