A while back I had a client sending me her blood sugar charts every few days and on those she always made some notes for me if she had any questions.
I noticed she had 3 big question marks (???) against one of her morning blood sugar results and then again on another morning when her blood sugar levels were high at 160 (mg/dl – or 8.9mmol/l).
She had written:
I don’t understand. 97 (mg/dl – or 5.5mmol/l) last night when I went to sleep. I didn’t eat anything because I didn’t feel well. Humm.
I was also over in one of the online diabetes groups I’m involved in today and this message popped up.
I’m struggling with my morning BS number. When I went to bed around 11PM my BS was 107. I’m waking up with my BS between 120 – 135. I did put two pieces of string cheese next to my bed and when I woke up around 3am, I ate one. Since I was told to eat protein at night. When I woke up 3 hours later my BS was 130. I didn’t want to eat anything large since it’s so close to 140 (my goal is to keep it below 140). So I had 1 piece of toast (sugar free wheat bread) and just a tiny bit of peanut butter. I checked it an hour later and it was 161! What am I doing wrong?
In fact one of the most frequently asked questions is:
Why is blood sugar high in the morning?
Logically we’d think that it should be at it’s lowest in the morning right?
Well don’t panic, there is a reason for it, so let’s explore why morning blood sugar is often higher, and in my next post I’ll share 10 practical tips on bringing it under control.
Why Is Blood Sugar High In The Morning?
Although it would seem logical that your body would have the lowest blood glucose in the morning this often isn’t the case for these 5 reasons.
1. Glucose Happens 24/7
All the cells in the body need glucose to fuel their function, even when we sleep. So the body breaks down stores in the liver so that the body and brain can continue to go about their functions. This glucose production will still occur when you don’t eat and in fact if you skip a meal it can increase the livers production of glucose.
2. Hormones Raise Blood Glucose
Cortisol (our stress hormone) is the hormone that slowly increases in levels from around 3 am onwards to reach it’s peak early in the morning. This occurs to get us moving and to give us energy. There are also other hormonal factors involved in blood sugar regulation that can influence your highs. But as a natural consequence of rising cortisol, this stimulates a rise in blood glucose so it is in fact a ‘normal’ response.
But if you are diabetic there is one factor that impacts both the overnight glucose production and the rise in glucose with cortisol, and that is decreased insulin production.
3. Decreased Insulin Production
Because most type 2 diabetics naturally have decreased insulin production there is not enough insulin being produced to bring these rising levels down, even during the night when you are sleeping. Your body is still producing glucose, your hormones are still doing their thing, but insulin production is low and this is especially so during periods of fasting.
So in the first case we mentioned above where the woman didn’t eat anything this explains why her morning levels were so high the next day.
It’s never a good idea to skip a meal when you have diabetes.
4. Hypoglycemia known as the Somogyi effect
This is less common but in some people with diabetes low blood sugar (hypoglycemia) can occur while you are sleeping. This can also cause more glucose production. Remember our cells need it so if the body thinks it’s low it will naturally produce more. So if you’re trying to identify why your blood sugar is so high in the morning, you might want to wake yourself up during the night to test it, just in case this might be your situation and your insulin needs to be adjusted. You can read more about the somogyi effect here.
5. Poor Food Choices
The last thing that can have an effect is poor food choices. Regardless of the time of day poor food choices will impact your glucose levels negatively.
Okay, so we know the reasons why it happens but what can we do about it?
Some Blood Sugar Numbers
Just so you don’t go into a mad panic, here are some numbers you might find helpful.
- Upon waking (fasting) 70-130 mg/dl or 4-7.2 mmol/l
- An hour after meals up to 180 mg/dl or 10 mmol/l – this is when you reach your glucose peak
- 2 hrs post meal the ideal is 140 mg/dl or 7.8 mmol/l
- Before bed 90-150 mg/dl or 5-8.3 mmol/l
Read more about blood sugar levels here.
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