Is My Blood Sugar
Normal?
“Is my blood sugar normal?” seems
like a simple question – but it’s not! The answer can vary dramatically based
on your situation. Let’s look at some of the factors to consider. Please
remember: you should figure out your personal goals in consultation with your
doctor.
Normal Blood Sugar in Diabetic vs. Non-Diabetic
First, a quick note on how we
measure blood sugar. In the USA, blood sugars are measured by weight in
milligrams per deciliter, abbreviated as mg/dL. Most everyone else uses
millimole per liter, abbreviated mmol. If you are in the USA, look at the big
numbers, most everyone else look at the small numbers.
In a person without diabetes,
blood sugars tend to stay between 70 and 100 mg/dL (3.8 and 5.5 mmol). After a
meal, blood sugars can rise up to 120 mg/dL or 6.7 mmol. It will typically
fall back into the normal range within two hours.
These
are normal blood sugars in someone without diabetes. Source: Thriving with
Diabetes
In a person with diabetes, the story is
much more complex:
|
Below 70 mg/dL
Below 3.8 mmol |
Low Blood Sugars
(Hypoglycemia). When blood sugars drop
below this level, you may start feeling hunger, shakiness, or racing of the
heart. Your body is starved for sugar (glucose). Read how
to detect and treat low blood sugars.
|
|
70 mg/dL to 140
mg/dL
3.8 mmol to 7.7 mmol |
Normal Blood Sugar. In this range, the body is functioning normally. In
someone without diabetes, the vast majority of the time is spent in the lower
half of this range.
|
|
140 mg/dL to 180
mg/dL
7.7 mmol to 10 mmol |
Elevated Blood
Sugars. In this range, the body can
function relatively normally. However, extended periods of time in this zone
put you at risk for long-term complications.
|
|
Above 180 mg/dL
Abovoe 10 mmol |
High Blood Sugars. At this range, the kidney is unable to reabsorb all
of the glucose in your blood and you begin to spill glucose in your urine.
Your body may begin to turn to fat for energy and release ketones in your
urine. (You can purchase strips to test your urine for ketones. Contact your
doctor immediately if you have ketones in your urine.)
|
Normal Waking Blood Sugar (or Fasting Blood Sugar)
Ideally, everyone with diabetes will
wake up with blood sugars in the normal range. However, many people experience
what is called the “dawn phenomenon.” As the body prepares to wake and start
moving, it releases stored sugar into the blood. This can cause a moderate
spike in blood sugar. You can read How
to Fix High Morning Blood Sugars for
tips on how to improve these numbers.
To confirm if this is happening to
you, you can wake up in the middle of the night and check your blood sugar. If
it’s in the normal range then but high after waking, this is probably the
cause. If the spike is small and goes away quickly, then it’s likely nothing to
worry about (check with your doctor). The spike from dawn phenomenon is often
less than the one you get from eating a typical meal.
Morning blood sugars can also be
impacted by what happened the night before. The amount of carbohydrates you ate
and how much medicine you took can have an impact. Even stressful night of
tossing and turning can lead to high blood sugars. Learning what causes your
blood sugars to rise and fall by checking your blood sugars strategically is the
key to figuring out why your blood sugars are what they are in the morning.
Normal Blood Sugars After Meals (or Post-Prandial Blood Sugar)
The chart below
compares post-meal blood sugars in a typical person with diabetes and
someone without diabetes. Most diabetes organizations recommend
keeping your post-meal rise below 180 mg/dL or 10 mmol.
So is 200 mg/dL or 11 mmol a
surprisingly high blood sugar an hour after a meal? If you were at 150 mg/dL or
8.3 mmol before you began eating, then probably not. Your meal only caused a
modest bump of 50 mg/dL or 2.8 mmol. That would be perfectly reasonable in
someone with a perfectly functioning pancreas!
To know whether a blood sugar is
what one would expect, it’s important to understand where you started. If you would
like to reduce your blood sugars after meals, read How
to Start a Low-Carb Diabetes Diet.
What Blood Sugar Levels Are Healthy?
This is an area of some debate. The
long-term studies show that the risk of complications drop off dramatically
when an HbA1c is lower than 7%, an estimated average blood glucose of 154 mg/dL
or 8.6 mmol. It continues to drop until it’s below 6%, an average blood sugar
of 126 mg/dL or 7 mmol. There are many people who strive for lower
targets, but there is not a lot of research outlining the benefits of that
approach yet.
One challenge is that studies of A1c
are just looking at averages. In reality, there seems to be a huge
difference in risk of complications based on genetics. There are many people
who have lived thirty or forty years with type 1 diabetes running high blood
sugars almost continuously and have no complications. There are others who have
had nearly perfect blood sugars that still get complications. But for most people, it’s safe to say that
striving for an HbA1c of below 7% and probably below 6.5% is a realistic goal
for staying healthy.
There are exceptions, of course.
Doctors might often recommend higher targets for those that can’t sense low
blood sugars, are elderly or have some other health conditions. The reasoning
is that the health risks of striving for lower targets may be outweighed by the
risks of doing so. For example, most complications take decades to appear. If
someone is diagnosed with type 2 diabetes at 90, there’s almost no chance of
living to see those complications. So a doctor might prescribe less intensive
therapies.
There is also a lot of research
suggesting that the total time you spend in a health range is more
important than your A1c. For example, if your low A1c comes from a lot of
severe lows balancing out highs, this is less good than just having more steady
blood sugars near the normal range.
A Note About Meter Accuracy
In the USA, a meter can be approved
for sale so long as the results are consistently within 20% of the right
number. That means that if your blood sugar was 180 mg/dL or 10 mmol, than a
result of 216 mg/dL (12 mmol) or 144 mg/dL (8 mmol) would still be considered
accurate. In practice, most meters are more accurate than that, but even an
expensive hospital blood test using calibrated equipment has a 10% margin of
error.
So don’t automatically panic if you
check your blood sugar and it’s 140 mg/dL (7.7 mmol) and a few minutes later
it’s 150 mg/dL (8.3 mmol), a change of under 10 mg/dL or 1 mmol. This may just
be the meter. Look for trends over time to truly understand what’s happening.
You can check out this chart comparing
blood glucose meter accuracy.
Keep in mind that this study is not current and, unfortunately, that no one has
published more current data. (There should be some independent group testing
meter accuracy in the real world, but it just isn’t happening… yet.)
Is My Blood Sugar Normal?
So there you have it: a long and
winding answer to what seems like a simple question! And remember: please
consult your doctor to understand what healthy blood sugars are for you.
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