Type 2 Diabetes: High Blood Sugar Levels Before Bed

Diabetes is a common condition that affects around 10%¹ of people in the US. Approximately 90–95% of these people have type 2 diabetes.

Type 2 diabetes is not curable, but you can effectively manage it and even put it into remission. Monitoring your blood sugar levels is one of the best ways to keep the condition under control.

Blood glucose levels can change throughout the day. The reading you get will depend on many factors. Knowing what to expect from these fluctuations can help you identify a problem and take the necessary steps to manage it.

Let’s take a closer look at type 2 diabetes and what you should expect from your blood sugar levels before bed, in the morning, and throughout the rest of the day.

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Type 2 diabetes and blood sugar levels 

With type 2 diabetes, you will know your safe blood glucose range. It depends on many different factors, including the time of the day.

According to the CDC,² typical times to check blood sugar levels are:

  • When you wake up (before eating or drinking)

  • Before a meal

  • Two hours after you eat

  • Before bed

Under normal circumstances, your pancreas releases insulin in response to the rising glucose levels in your bloodstream. This usually happens when you eat something. Insulin allows the glucose to enter your cells and convert them to energy.

Insulin also helps your liver and muscles store glucose and keeps the liver from producing new sugar or releasing the stores.

People with type 2 diabetes can’t process glucose normally, so their blood sugar levels can stay high for a long time. This could lead to various problems when unmanaged, including blood vessel damage and heart disease.

For this reason, your doctor will recommend controlling your blood sugar levels and taking action when they stay high for too long.

Normal blood sugar levels for people with type 2 diabetes 

Together with your doctor, you can determine your ideal blood sugar goals for different times throughout the day.

Adults with type 2 diabetes should normally aim for the following typical ranges:

  • Before you eat: 70–130 mg/dl

  • After you eat: less than 180 mg/dl

  • At bedtime: 100–140 mg/dl

These numbers may differ from person to person, depending on underlying conditions, treatment, and age.

Call your doctor if your blood sugar levels before bed are consistently higher than 140 mg/dl. You might need to adjust your treatment or change your routine.

What causes high blood sugar levels before bed?

Reasons for blood sugar level spikes before bedtime can differ for each person with diabetes.

The most likely reasons are:

  • Dosage and timing of insulin medication: Your blood sugar levels may be too high if the insulin dosage is too low or if you take your medication at the wrong time.

  • Late dinner: If you snack before going to sleep, your blood glucose levels will be outside the normal “pre-bed” range.

  • Too many carbs: Your blood sugar levels may stay high for longer if your dinner contains too many carbohydrates.

  • Illness, infection, or injury: Sickness, infections, and injuries increase inflammation and stress in your body. This causes excessive adrenaline and cortisol production, which reduces insulin sensitivity and increases blood glucose levels.

  • Stress: Feeling stressed in the evening can affect your blood sugar levels. Stress can also cause you to overeat, which can lead to hyperglycemia (high blood glucose levels).

Going to sleep with hyperglycemia can be uncomfortable and dangerous.

Dangers of going to sleep with high blood sugar levels 

An occasional rise in blood sugar levels before bed is not usually a cause for concern. However, frequent hyperglycemia at night can be harmful.

High blood sugar levels before bed can cause:

Poor sleep

Studies³ show people who can’t manage their blood sugar levels during the night face poor sleep. Sleep deprivation can:

  • Increase cortisol levels

  • Reduce insulin sensitivity

  • Increase oxidative stress (imbalance between antioxidants and free radicals) and inflammation

High blood sugar levels before bed and poor sleep form a cycle, as these effects cause blood sugar levels to rise.

Health complications 

If you don’t control your blood sugar levels before bed and during the night, you could face hyperglycemia complications. These include:

  • Diabetic retinopathy: Growth of abnormal blood vessels on the retina (causes vision problems).

  • Nephropathy: Problems with kidney function.

  • Neuropathy: Nerve damage that causes numbness, tingling, and pain in affected areas.

  • Coronary artery disease: Plaque buildup in your arteries that could lead to blockage and possibly a heart attack.

  • Cerebrovascular disease: Problems with blood flow to the brain, which could result in a stroke.

  • Peripheral vascular disease: Problems with blood circulation.

You could also start experiencing depression, a mental health condition that could impact your blood sugar levels.

Diabetic ketoacidosis 

If blood sugar levels regularly increase before bed and continue rising during the night, you could develop diabetic ketoacidosis (DKA).

When your body doesn’t have enough insulin to convert glucose into energy, it searches for another fuel source. As an alternative, it uses stored fat for energy by employing ketones produced by the liver. The excess ketones in your blood cause DKA.

Diabetic ketoacidosis is a serious condition that could lead to:

  • Organ damage

  • Brain swelling

  • Muscle weakness

  • Heart rhythm problems

DKA is a medical emergency that requires immediate attention.

How to lower blood sugar levels before bed 

If you check your blood sugar levels in the evening and see high readings, you need to rethink your daily routine so it doesn’t happen regularly.

Review your meals

You need to give your body enough time to deal with the post-eating blood sugar spike. Try to avoid eating large late-night dinners and limit your carbohydrate intake.

Speak to your doctor about specific diet recommendations that are suitable for you and your health. They may refer you to a nutritionist.

Your doctor may recommend late-night snacks to help manage your blood sugar levels. According to research,⁴ you should opt for snacks high in protein and low in carbs, like hard-boiled eggs, roasted chickpeas, and low-fat cheese with whole-wheat crackers.

Exercise before bed

Gentle exercise before bed can help reduce your blood sugar levels. Consider taking a walk or practicing yoga. Avoid strenuous exercises as they could increase glucose levels in your blood. 

Avoid stressful situations

Feeling stressed before bed is very damaging to your health. Besides preventing you from falling asleep quickly, it can spike your blood glucose levels.

If you feel stressed during the day, consider practicing relaxation techniques before going to bed. You could try gentle breathing or progressive muscle relaxation. Yoga and other non-strenuous exercises can also help manage stress levels before sleeping.

Adjust your medication

Speak to your doctor about high blood sugar levels before bed if you take insulin. You may need to adjust your dose or change the time when you take your meds.

Other medications could be affecting your blood sugar levels before bed, so speak to your doctor about any other drugs you are taking.

Medications such as steroids, birth control pills, beta-blockers, antidepressants, diuretics, and nasal decongestants may increase your blood sugar levels. Talk to your doctor about changing the time you take these medications.

Focus on your comfort 

People living with type 2 diabetes often have other underlying health conditions. These conditions often cause aches, pains, and other symptoms that could keep you from relaxing and enjoying a good night’s sleep. This could cause high blood sugar levels.

Take steps to make your bedroom more comfortable, such as:

  • Turn off or dim the lights

  • Use a comfortable mattress

  • Don’t use your phone for at least 15 minutes before sleep

  • Turn your cellphone’s sound off so it doesn’t wake you up during the night

  • Set the optimal sleep temperature (ideally between 65 ⁰F and 69 ⁰F).

If you are sleeping with a partner, coordinate your bedtime to avoid waking each other.

High blood sugar levels during the night and in the morning 

Your blood sugar levels may be normal before bed but rise during the night.

Symptoms of high blood sugar levels while you sleep include:

  • Sleeping poorly

  • Waking up frequently to urinate or drink water

  • Headache

  • Nausea

  • Dry mouth

When you sleep, your body doesn’t require as much fuel as it does when you are awake. However, when you wake up, your body gets ready to work and produce energy, and your liver begins releasing glucose into the blood. This causes the pancreas to release extra insulin to handle the rising blood sugar levels in your body.

With diabetes, your body can’t produce sufficient insulin to process the released glucose. This causes blood sugar levels to rise in the morning.

The Dawn Phenomenon 

When your body is getting ready to wake up, it releases specific hormones into your bloodstream. These hormones can work against insulin and cause blood sugar levels to rise slightly. This is called the Dawn Phenomenon.⁵ It usually occurs between 3 AM and 8 AM.

This rise goes unnoticed in non-diabetic people. They simply release more insulin to deal with the increase. However, the phenomenon can be challenging for people with diabetes.

The Dawn Phenomenon affects over 50%⁵ of people with type 1 and type 2 diabetes. If it affects you, discuss management techniques with your doctor. They may involve taking insulin at bedtime, avoiding late-night snacks, and exercising after dinner.

The Somogyi Effect

Using insulin to manage blood sugar levels before bed with type 2 diabetes could lead to something called the Somogyi Effect.⁶

Taking insulin before bed causes your blood sugar levels to drop. During the night, your body responds to the drop in blood glucose by releasing hormones like cortisol, adrenaline, and glucagon. These hormones cause your liver to release glucose, and your blood sugar levels rise as a result.

If you have low blood sugar levels during the night and high blood sugar levels in the morning, speak to your doctor. Before making an appointment, check your blood sugar levels:

  • Before sleep

  • At 3 AM

  • As soon as you wake up

Low glucose levels at 3 AM coupled with high glucose levels in the morning could indicate the Somogyi Effect.

Low blood sugar levels before bed 

Low blood sugar levels before bed are just as problematic as hyperglycemia for people with type 2 diabetes.

Some people with diabetes have a condition called nocturnal hypoglycemia. This occurs when blood sugar levels fall below 70 mg/dl.⁷

You are at risk of suffering from this condition if you:

  • Don’t eat dinner

  • Do strenuous exercise before going to bed

  • Drink alcohol in the evening

  • Develop an infection

The symptoms of nocturnal hypoglycemia include a racing heartbeat, changes in your breathing, poor sleep, nightmares, and sweating.

If they are low, you can increase your blood sugar levels by eating a healthy snack before bed.

The following steps can help prevent the problem from happening in the future:

  • Check your blood sugar levels before going to bed

  • Speak to your doctor about changing your insulin dosage and timing (hypoglycemia is more frequent⁸ in people who take insulin)

  • Don’t skip meals

  • Avoid drinking alcohol before bedtime

The lowdown 

To avoid complications, you need to keep your blood sugar levels under control at all times if you have type 2 diabetes.

You may notice abnormal readings when you measure your blood sugar levels before going to bed. If this happens regularly, you may need to adjust your habits and medication.

Learning all you can about type 2 diabetes and what affects your blood sugar levels before bed can help you avoid readings that are too high or low.

Speak to your doctor about the best ways to manage your blood glucose levels in the evening and during the night.

Have you considered clinical trials for Type 2 diabetes?

We make it easy for you to participate in a clinical trial for Type 2 diabetes, and get access to the latest treatments not yet widely available - and be a part of finding a cure.

Joining community groups and exercise programs for my condition made me feel empowered – but I want to be part of finding a cure.
Peter, 64


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