Why is my blood sugar high in the morning even when I haven’t eaten anything? This is a question you may be asking yourself. Believe me, you are not alone. In diabetes or pre-diabetes it is common to wake up with blood sugar levels higher than the night before.
Fasting blood sugar
The fasting blood sugar (blood glucose) is the most common test used to assess the blood sugar levels. You would usually do this in the morning before breakfast. It is easy to do at home with a personal blood glucose monitor which most people with diabetes have.
You usually check your fasting blood sugar after fasting over night. This means you don’t eat or drink anything except water for at least 8 hours before you do the test.
Naturally you would expect the following pattern. You eat dinner, perhaps you check your blood sugar an hour or two after eating. Then you would fast overnight and check your blood sugar before breakfast.
You would expect your morning fasting blood sugar number to be lower than what you had before you slept.
It doesn’t always work that way!
Much to your frustration, you find that your blood sugar isn’t lower! In fact, it’s even higher. There are a couple of reasons why you may be having this problem. I’ll go through them all and explain what’s happening and what you can do about it.
If you have diabetes, you’ll find it more difficult to regulate the levels of sugar in your blood. In type 1 diabetes the body is not able to produce enough insulin. There is an absolute lack of insulin in the body.
In type 2 diabetes the body produces insulin and initially very large amounts. But the body cannot use the insulin effectively. This is insulin resistance. Insulin is the hormone that helps the body cells to take up sugar from the blood. The cells use this sugar for energy.
Normal blood sugar levels
The main symptom of all types of diabetes mellitus is high blood sugar. Diabetes is diagnosed with a fasting blood sugar over 125mg/dl or a random blood sugar above 200mg/dl. The aim of most diabetic treatment in non-pregnant adults is to maintain a fasting blood sugar within certain levels:
- between 70 and 130 mg/dl and
- 2-hour postprandial (2 hours after eating) blood sugar level under 180mg/dl.
In pregnant diabetic women:
- the fasting blood sugar should not be above 90 mg/dl,
- the 1 hour postprandial blood sugar should not be above 140mg/dl
- the 2-hour postprandial blood sugar should be less than 120mg/dl.
The dawn phenomenon (and extended dawn phenomenon)
By far, the most common cause of very high morning fasting blood sugar levels is the dawn phenomenon.
The dawn phenomenon refers to recurring high blood sugar occurring in the early morning before breakfast. Sometimes it may extend into the late morning after breakfast. This is an extended dawn phenomenon.
The body has a circadian rhythm. During this daily cycle the body is programmed to do certain things at certain times of the day. For example in the evening your body starts to wind down. This prepares you to gradually become less active and eventually to go to sleep.
In the early morning, changes take place in your body. These changes prepare you to tackle a day of activity and challenges. This happens in every normal human being.
Insulin secretion goes down in the early hours of the morning. This allows for secretion of insulin antagonist hormones which raise the blood sugar.
Hormones that work to raise the blood sugar
From around 4 a.m. to 8 a.m. the body starts to release certain hormones. They tell it to wake up and be alert. These are the hormones that help you to get out of bed in the morning.
Hormones are chemicals which travel around the body telling different cells and organs what to do. These hormones that are released in the morning include;
- cortisol which is a stress hormone
- growth hormone
- glucagon
- thyroid hormone
- adrenaline or epinephrine
Under the influence of these hormones, in the early morning hours the liver starts to break down stored glycogen. This releases glucose into the blood. The liver also increases production of glucose from other sources like stored fat.
This leads to a rise in blood sugar. If you don’t have diabetes the body responds by producing more insulin. So as the blood sugar goes up the insulin levels go up as well. This tells the liver to stop producing and releasing more glucose into the blood. It also tells the cells to take up glucose from the blood.
Some diabetics do not have this response to the early morning rise in blood sugar. The blood sugar continues to go up to abnormal levels. There is no increase in the production of insulin. The liver just keeps producing and dumping in glucose into the blood, even as the blood sugar levels are rising higher and higher.
Who has high blood sugars in the morning?
The dawn phenomenon occurs in both type 1 and type 2 diabetics and can also occur in pre-diabetics.
If you are a type 2 diabetics who have dawn phenomenon you may have problems with your pancreatic beta cells. When the liver is dumping glucose into the blood, the pancreas does not produce insulin. It cannot respond to the high blood sugar levels.
In type 1 diabetics, the dawn phenomenon occurs when the insulin you injected the previous day is not enough to compensate for the early morning rise in blood sugar. This means that:
- basal insulin injections are too low or
- the intermediate acting insulin dose injected the night before is not high enough to compensate for the morning rise in blood sugar. The effects of the injected insulin start to wear off at about the same time as the release of the hormones. This raises blood sugar and opposes the effects of insulin.
About 50% of people with type 1 and type 2 diabetes may experience the dawn phenomenon. Recurring morning hyperglycemia (very high blood sugar levels) can cause insulin resistance. This can lead to a worsening of glucose tolerance and make the disease worse.
The Extended Dawn Phenomenon
If the morning glucose remains high until mid-morning you may have the Extended Dawn Phenomenon.
Possible causes of the extended dawn phenomenon include:
- eating too many carbohydrates for breakfast and
- abnormal growth hormone secretion.
Growth hormone is normally released into the blood which raises the blood sugar. The levels gradually come down as the morning progresses. But some people with diabetes have an abnormal pattern of growth hormone production. The growth hormone continues to be produced even when insulin has been secreted which keeps the blood sugar high.
Insulin
Insulin acts as a kind of gatekeeper to many hormones. Hormones produced early in the morning that contribute to the dawn phenomenon cannot be released in the presence of high insulin levels. So the low insulin requirements during the night allows these hormones to be secreted.
When you eat, the insulin level rises and then comes down again. Seeing as you’re not eating during the night, the pancreas does not produce much insulin. During the night when you’re not eating the insulin level drops quite low. This reduction in insulin allows the other hormones like growth hormone, epinephrine, cortisol and thyroid hormone to be released into the blood. These hormones work as antagonist to insulin. They raise the blood sugar while insulin brings down the blood sugar.
Tests for the dawn phenomenon
Both the dawn phenomenon and the Somogyi effect can be a reasons why blood sugar is high in the morning. So you need to be able to tell them apart because the treatment for them is different.
There are two ways to do this:
- Test the blood sugar between 3 and 4 a.m. for several days. In the dawn phenomenon the blood sugar should be normal or high at this time. In the presence of the Somogyi effect the blood sugar will be low.
- Check the blood sugar levels with a continuous glucose monitor (CGM). This is a small machine that you attach to the skin to detect changes in blood sugar levels throughout the day. A computer processes and interprets the information. This will show whether the blood sugar is low normal or high between 3 and 4 a.m. This helps differentiate between the dawn phenomenon and the Somogyi effect.
Treatment and prevention of the dawn phenomenon
You can bring down high morning blood sugar levels over time in several ways.
Exercise
Engage in some physical activity after your evening meal. Go for a brisk walk or do something you find enjoyable but not too exciting (as this may stop you from falling asleep).
This activates your muscles so that they can take up glucose from the blood. Physical activity after your evening meal actually helps with blood glucose control throughout the whole of the next day. It is something that you should try.
Change what and when you eat
- Eat a meal that’s high in protein and low in carbohydrates.
- Have more fish, meat, eggs, chicken etc. with your meals.
- Eat less starchy foods like pasta and bread. It’s also best to avoid processed and packaged food and to eat natural whole foods as much as possible.
- Eat dinner earlier in the day. Instead of eating around 8 p.m., eat your dinner before 6 p.m.. You may find this difficult to pull off depending on how and where you work and how you structure your day. It may also not work for you if you have a family and you like to eat dinner together. But it is definitely something you should consider if you can make it work.
- Take a tablespoon of apple cider vinegar in half a glass of water after your evening meal. It helps to reduce the absorption of carbohydrates into the blood from the intestines.
Medication
- Increase your morning dose of diabetes medication
- Switch to an insulin pump and program it to release more insulin in the morning
Why blood sugar is high in the morning – The Somogyi effect
Another way you can describe this is rebound hyperglycemia. This is another reason why blood sugar is high in the morning. The Somogyi effect is named after the doctor who first put forward the idea.
It occurs in type 1 diabetics and only in type 2 diabetics who are on insulin. The Somogyi effect refers to a situation in which there is very low blood sugar during the night followed by high blood sugar in the morning. This is your body trying to save you from the dangers of having a blood sugar that’s too low. In the body’s attempt to raise the blood sugar and prevent the complications of having a very low blood sugar, the blood sugar levels overshoot and become very high in the morning.
Your body tries to keep you alive by producing hormones that raise the blood sugar. These hormones tell the liver to release glucose into the blood. In a diabetic the system does not work efficiently and the liver releases more sugar than the body needs. This leads to a very high blood sugar in the morning.
Signs that you may be having very low blood sugar during the night
Signs that your blood sugar may be dropping very low during the night include:
- waking up with a headache,
- sweating profusely during the night,
- having nightmares.
Why blood sugar is high in the morning – dawn phenomenon vs Somogyi
In both the dawn phenomenon and the Somogyi effect, the main symptom is very high blood sugar in the morning. So it’s important to be able to tell them apart to make sure the right kind of treatment is given. Once again the blood sugar should be measured between 3 and 4 a.m.. If it is very low repeatedly over several night this suggests that you’re suffering from the Somogyi effect.
How to prevent the Somogyi effect
You can prevent the Somogyi effect by making changes to what you eat. You can also adjust your medication.
- Eat more protein and less carbohydrate with your evening meal.
- Adjust your insulin regimen with your doctor’s help to make sure that you’re not having too much insulin or to reduce your insulin. Change your dosage to make sure that you don’t have hypoglycemia during the night.
- Use an insulin pump to administer your insulin. Program it to give you a higher dose of insulin in the morning.
- Eat a carbohydrate snack before going to bed.
- If you exercise in the evening do it earlier in the day.
Problems you may have when blood sugar is persistently high in the morning
You may start experiencing the dawn phenomenon early on when you develop diabetes. If it is not treated it can lead to a worsening of diabetes. It can also increase your chances of developing cardiovascular disease (problems with your heart and blood vessels) and problems with your nerves (neuropathy).