There are many reasons you might need a blood sugar test. If you’ve gotten a diabetes diagnosis, monitoring your blood glucose (sugar) at regular intervals might be part of your care plan. Even people without diabetes may have their blood sugar checked during an annual physical exam or during pregnancy as part of routine prenatal care.

Measuring morning blood sugar levels can be especially useful because they show how your body manages glucose overnight. What’s considered normal blood sugar when you wake up can vary from person to person. If you’re living with diabetes and you notice your blood glucose level is high in the early morning, several factors could be at play.

The good news is there are practical steps you can take to help bring your morning blood sugar levels into a healthier range. In this article, we discuss why morning blood sugar levels may be high and share tips on how to manage them.

What Is a Good Blood Sugar Level in the Morning?

Blood glucose readings taken in the early morning are usually done before eating or drinking. Because of this, they’re often referred to as fasting blood glucose tests. These tests check glucose levels when you’ve had nothing to eat or drink, besides water, for at least eight hours.

Normal blood sugar values first thing in the morning depend on whether you have diabetes. According to the American Diabetes Association (ADA), the normal ranges for fasting blood sugar levels are usually:

• For people without diabetes who aren’t pregnant — Below 100 milligrams per deciliter (mg/dL)
• For people with diabetes who are taking medications — Between 80 mg/dL and 130 mg/dL

• For pregnant people — 91 mg/dL or lower

If you live with diabetes, your doctor may recommend a slightly different goal range. For example, older adults, people with other health conditions, or those who don’t notice symptoms of low blood sugar may be given higher targets.

Also, keep in mind that lower isn’t always better. For people with diabetes, a blood sugar reading below 70 mg/dL on a fasting blood glucose test is considered hypoglycemia (low blood sugar). For someone without diabetes, that number may be normal.

Why You May Have High Blood Sugar in the Morning

So, why might you have high blood sugar levels in the morning if you have diabetes? It’s not like you just ate a meal full of carbs. There are a few possible reasons, including something called the dawn phenomenon.

The Dawn Phenomenon

The dawn phenomenon is a common cause of hyperglycemia (high blood glucose) in the morning for people living with diabetes. This rise in blood sugar tends to happen between 4 a.m. and 8 a.m., which is why it’s called the “dawn” phenomenon. It affects about half of people with type 2 diabetes and type 1 diabetes.

According to the ADA, the dawn phenomenon happens when certain hormones, like cortisol, prompt the body to make glucose as the night ends. Glucose gives your body energy and helps you wake up. But if you have diabetes, your body may not have enough insulin to lower blood sugar the way it should.

Reasons you may not be able to counteract this rise in blood sugar while you sleep include:

• Your body doesn’t make enough insulin on its own.
• You have high insulin resistance.
• You didn’t take the right dose of your diabetes medication or your insulin the night before.
• You ate carbohydrates (carbs) before going to sleep.

If you often wake up with high blood sugar, talk with a healthcare professional. They may suggest you start wearing a continuous glucose monitor (CGM) to track your blood glucose levels while you sleep.

Insulin Levels Dropping Too Much While You Sleep

Insulin is a hormone that helps keep blood sugar in check. Sometimes, insulin levels drop too low while you sleep. When this happens, your body reacts by raising your blood glucose too much. This can happen for several reasons.

Common causes of insulin levels falling too low at night include:

• Taking a dose of long-acting insulin that’s too low
• Using an insulin pump that isn’t programmed to give the right amount of insulin while you sleep
• Taking your long-acting insulin dose too early in the evening

The Somogyi Effect

Another possible reason for high blood sugar in the morning if you have diabetes is the Somogyi effect. This theory, first described by Dr. Michael Somogyi in the 1930s, is based on something called “rebound hyperglycemia.”

Somogyi’s theory states that episodes of hypoglycemia during sleep can trigger a rush of hormones such as growth hormone, glucagon, corticosteroids, and adrenaline. These hormones work to raise your blood sugar back into a healthy range. But in some cases, these hormones may raise blood sugar levels too much, leading to high blood sugar in the morning.

However, studies using CGM have not found strong evidence that the Somogyi effect is a common cause of high morning blood sugar. While it may still happen in some cases, most scientists now believe the dawn phenomenon or other causes are more likely.

How To Lower Blood Sugar in the Morning

If you often wake up with high blood sugar levels, it’s important to understand why. Tracking your glucose levels at night can help. You can do this by checking your levels before bed, during the night, and in the morning or by using a CGM.

The best way to lower blood sugar levels depends on the cause. Here are some possible strategies.

Eat a Smaller Dinner

If your blood sugar is high at bedtime, your evening meal or late-night snack may be to blame. Eating a large dinner or foods that raise your blood glucose too much at night can cause blood glucose levels to stay high until morning. Try eating smaller meals later in the evening, eating earlier in the evening, or choosing foods with fewer carbs.

Adjust Your Insulin Dose

If you aren’t taking enough insulin to manage the rise in blood glucose that comes with your evening meal, your levels may stay high overnight. In some cases, taking more insulin with dinner can help.

Adjust Your Insulin Timing

If your blood sugar is within the normal range at bedtime but you wake up with high glucose levels, your medication may be the cause. This can happen if your long-acting insulin is wearing off too soon before your next dose. If this happens, adjusting the time of your dose may help. You can also talk to your doctor about options like splitting your insulin dose into two injections a day or using an ultra-long-acting insulin.

Get Moving

Exercise can help keep blood sugar levels under control, including in the morning. Taking a walk after your evening meal or doing another kind of physical activity in the evening can have effects that last through the night. But if you often have low blood sugar while you sleep, try exercising in the morning instead. This may help prevent your levels from dipping too low overnight.

Talk to Your Doctor

Waking up with high blood glucose levels too often can raise your A1C. If your morning blood sugar readings stay high even after you make changes, talk with your doctor about your diabetes treatment plan. Your healthcare provider may recommend adjusting your morning blood sugar goal to be slightly higher or changing your treatment plan. For example, if the dawn phenomenon is the cause, your doctor may recommend using an insulin pump.

Together, you and your doctor can create a diabetes management plan that fits your needs and helps bring your morning blood sugar into a healthy range.

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