Does High Blood Sugar Make You Sleepy? Here’s Why And Tips

High blood sugar is a common cause of fatigue. Learn why this happens and what you can do to prevent it.

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Science-based and reviewed

May 28, 2023
January 10, 2023
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If you’ve ever eaten a high carb meal (safe to say that’s everyone), you may have felt really tired right after eating. Or may you felt a burst of energy followed by a crash an hour to so later, leaving you feeling fatigued and lethargic. 

Ever wonder why? High blood sugar. When blood sugar gets too high, it can be difficult for insulin (a hormone secreted by the pancreas) to pull glucose from the blood and into cells to give them energy. Often times, a spike in blood sugar (hyperglycemia) leads to a significant dip in blood sugar (hypoglycemia), which can also leave you feeling tired. 

In this article, we will dive into why high blood sugar makes you tired, other symptoms of high blood sugar, and ways to prevent it. 

Can High Blood Sugar Make You Tired? 

People with high blood sugar commonly feel tired. Studies show that 61% of those diagnosed with diabetes often feel tired and sluggish.1 

Even when people with diabetes take steps to actively manage their blood glucose levels – for instance, engaging in regular exercise, proper nutrition, adequate sleep, and stress management – they may still feel tired. People with normal to prediabetic blood sugar levels can also feel tired when they experience significant spikes in blood sugar. 

When blood sugar rises rapidly, the body immediately works to return blood sugar levels to normal. It does this by creating insulin. In diabetes, there either isn’t enough insulin, or the cells do not respond to insulin as they should. This kicks the body into overdrive and it starts pulling energy from fat. 

The body uses energy from the breakdown of the molecule called adenosine triphosphate (ATP). ATP gives off one of three phosphates for energy, and it changes to a different molecule known as adenosine diphosphate (ADP). When ATP cannot regain the phosphate initially lost, this leads to tiredness.2

Managing Tiredness: Tips to Avoid Feeling Sleepy

If you have high blood sugar, here are some practical tips to avoid feeling tired and increase energy levels with high blood sugar: 

  • Get adequate sleep: Getting at least 8 hours of sleep each night can help to avoid feeling sleepy. If you aren’t currently sleeping this much, try adopting a bedtime routine that may help improve the quality of your sleep. Go to bed and wake at the same time each day, and practice a nightly routine that tells your body and brain that it’s time to catch some zzz’s. 
  • Take care of your mental health: Depression, anxiety, and emotional stress are common factors that are often seen in people with high blood sugar. Taking time out to care for your mental health can prevent exhaustion. Consider seeing a therapist, practicing meditation, or some other form of self-care. 
  • Don’t skip meals: Eating at regular intervals can help keep energy levels stable and prevent tiredness. Avoid skipping meals and eat a balanced meal or snack every 3-4 hours. A balanced meal or snack includes carbohydrates, protein, and fat. For example, cheese, crackers, and turkey; or Greek yogurt, fruit, and granola.  
  • Drink coffee or tea without added sugar: Drinking caffeine-containing beverages can provide you with a boost of energy, but you’ll want to avoid beverages that contain added sugars that will contribute to high blood sugar. Opt for unsweetened teas or use artificial sweeteners like stevia, monk fruit sweetener, or sucralose. 
  • Avoid alcohol: Alcohol can disrupt sleep patterns, so while you may be getting enough sleep, it won’t be good quality sleep. This will cause you to wake up feeling tired and unrested. If you choose to drink, limit yourself to 1-2 servings of alcohol per day. Avoid drinking daily.

What Are High Blood Sugar Symptoms? 

High blood sugar is easy to identify. When caught and managed early on, you can take steps to prevent chronically high blood sugars that can lead to prediabetes, diabetes, and other types of metabolic syndrome. Here are some early signs to watch out for: 


Extreme fatigue is one of the hallmark symptoms of high blood sugar (and diabetes). Studies suggest that fatigue related to high blood sugar is likely caused by a lack of glucose to supply energy due to rapidly fluctuating blood sugar levels.3 

Low blood sugar can also cause fatigue. Other conditions and lifestyle factors can worsen this symptom, including dehydration, poor sleep quality, physical inactivity, poor diet, mental health issues, and hormonal imbalances. 

Frequent urination

Frequent or excessive urination, also known as polyuria, is a sign that your blood sugar levels are too high. So much so that they “spill” into your urine. When your kidneys can’t keep up to filter out the amount of glucose in your blood, they allow some of it to go into your urine. This makes you have to urinate often, especially at night. 

Increased thirst

Extreme thirst is another hallmark symptom of high blood sugar and is often made worse by frequent urination. Usually, drinking won’t quench the thirst.

Increased hunger

Increased hunger, also called polyphagia, can also be an early warning sign of diabetes. The body uses the glucose in the blood to feed its cells. When this system is broken, cells can’t absorb glucose. As a result, the body is constantly looking for more fuel, causing constant hunger.

Blurred vision

Blurred vision often occurs in people with unmanaged diabetes, and can be an early warning sigh of chronically high blood sugar. Blurred vision can occur due to sudden spike in blood sugar. High blood sugar affects the tiny blood vessels in the eyes, causing fluid to seep into the lens of the eye. In the early stages, blurriness will usually resolve, but you should still see an eye doctor right away.

When high blood sugar levels are chronic, there is an increased risk for more serious conditions that can lead to blindness, like diabetic retinopathy.

Frequent infections

Anyone can develop a bacterial, fungal, or yeast infection, but people with high blood sugar tend to get them more often.

When blood sugar is too high for the kidneys to filter it well, sugar ends up in the urine. This may cause urinary tract infections (UTIs) and yeast infections. Infections of the gums and skin are also common.

Slow healing wounds

There are a number of reasons that wounds heal more slowly in people with high blood sugar. High blood sugar levels narrow your blood vessels over time, which decreases blood circulation and limits nutrients and oxygen from reaching healing wounds. Chronically high blood sugar levels also cause damage to your immune system, so your body isn’t as good at fighting off infection.


Irritability or changes in mood can indicate blood sugar levels that are too high. Of course, there are other medical conditions that can cause mood swings. If you’re feeling more irritable than usual, don’t automatically assume you have high blood sugar. 

Changes in mood that are related to high blood sugar will usually be present with other signs of high blood sugar. There is increasing evidence that indicates a relationship between mood and highs and lows in blood sugar.4

6 Ways to Prevent Blood Sugar Spikes

If you have high blood sugar, there are some things you can do to lower your blood sugar and keep energy levels more stable. Here’s how to prevent blood sugar spikes that can make you feel sleepy:

Eat balanced meals and snacks

Make sure your meals are balanced by including all three macronutrients – carbohydrates, protein, and fat. When carbohydrates are eaten alone without fat or protein, the body quickly digests the carbohydrates and causes blood sugars to spike. Focus on whole foods, like nuts, dairy products, whole grains, fruits, and vegetables. 

Exercise regularly

Moving your body on a regular basis can help regulate blood sugar levels. Both high-intensity and moderate-intensity exercise typically deliver the same results, so choose a form of exercise that you enjoy and can remain consistent with. Just walking for 30 minutes daily can make a huge difference in managing blood sugars.

Swap simple carbs for complex carbs

Eating simple carbs like those from white bread, table sugar, and breakfast cereals can cause spikes in blood sugar because they are quickly and easily digested. Unlike simple carbs, complex carbs are more slowly digested, decreasing the occurrence of blood sugar spikes. 

Consuming adequate vitamins and minerals

It’s important to consume enough essential vitamins and minerals in your daily diet. Eating a wide variety of foods including lean proteins, fruits, vegetables, whole grains, dairy, nuts, and seeds can help increase your intake of these essential nutrients. If you don’t get enough of these vitamins and minerals in your diet, consider taking a multivitamin to fill in the gaps.

Taking time to destress

Chronic stress can contribute to high blood sugar levels.5

To prevent increases in blood sugar that are caused by external stressors (i.e. work, family, life, etc.), find ways to manage stress like therapy, meditation, yoga, or journaling. 

Be mindful of the glycemic index (GI) of foods

The glycemic index ranks carbohydrates on a scale from 0 to 100 based on how quickly and how much they raise blood sugar levels after eating. Foods that have a high glycemic index, like white rice, are rapidly digested and cause substantial spikes in blood sugar. 

The glycemic index was developed based on how the foods affect blood sugar when eaten alone. If you eat high-GI foods, just add something that has fat and protein to help slow digestion and prevent blood sugar spikes. 

Potential Consequences of High Blood Sugar Levels

Over time, when high blood sugar levels are left unmanaged, glucose builds up in the bloodstream and cells do not receive the energy they need. When cells cannot use glucose for energy, they start to use fat instead. 

When cells in the body use fat for energy instead of glucose, ketones are produced during this process. This affects people who have diabetes more severely than those who don’t.

People who have diabetes may develop a potentially deadly condition called diabetic ketoacidosis (DKA). This condition decreases the pH of the blood, causing it to become too acidic. People with diabetes do not have normal insulin functioning, so ketone levels can rise to deadly levels very quickly. Untreated DKA can result in coma or death.

People with normal insulin functioning can manage certain levels of ketones in the blood. This is called a state of ketosis. People who do not have diabetes will not develop ketoacidosis because their bodies are able to properly manage glucose levels with insulin. Normal insulin functioning keeps the body’s ketone levels at an appropriate level. 

Signs of DKA include 

  • Nausea and vomiting
  • Severe dry mouth
  • Trouble breathing
  • Fruity-smelling breath or sweat
  • Weakness
  • Abdominal pain
  • Confusion
  • Coma

DKA is a dangerous condition that requires immediate medical treatment. If you have any of the above signs or symptoms, call 911 or seek emergency medical treatment immediately. 

Other Common Causes of Fatigue

Having prolonged periods of fatigue is different than feeling tired or having low energy. Fatigue may make you feel tired, but it will also cause a lack of motivation, low energy, and decreased quality of life. There are many possible causes of fatigue. Fatigue can also occur due to certain lifestyle choices such as poor diet and physical inactivity. 

Along with high blood sugar, other causes of fatigue include 

  • Hormonal imbalances
  • Anemia
  • Chronic conditions causing inflammation
  • Stress
  • Acute illnesses
  • Lack of sleep
  • Unbalanced diet 
  • Mental health issues

When You Should Reach Out For a Pro

Feeling tired every once in a while is normal and usually shouldn’t cause concern for an underlying health issue. However, prolonged periods of fatigue may indicate something more serious and should be addressed by a health professional. 

It’s time to see your doctor if you have been feeling fatigued and: 

  • can’t think of any reasonable cause of your fatigue
  • have an increased body temperature
  • have had unexplained or unintended weight loss
  • feel very sensitive to colder temperatures
  • often have trouble falling asleep and staying asleep
  • concerns you may be depressed

If you have made adjustments to your lifestyle habits to address fatigue, including getting adequate sleep, eating a balanced diet, and managing stress, and your fatigue persists for more than two weeks, you should make an appointment with your doctor.

Continuous glucose monitors (CGMs) help monitor and manage blood sugar levels. With a CGM, you can see how meals, exercise, and illness impact glucose levels. CGM wearers are alerted when glucose spikes or drops outside of a specific range. CGMs aren’t just for people who have diabetes. A CGM can help anyone monitor their blood sugar levels to make sure they are within normal limits. Learn more about continuous glucose monitoring with Signos to see how a CGM can help you.

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  1. Goedendorp MM, Tack CJ, Steggink E, Bloot L, Bazelmans E, Knoop H. Chronic fatigue in type 1 diabetes: Highly prevalent but not explained by hyperglycemia or glucose variability. Diabetes Care. 2013;37(1):73-80. doi:10.2337/dc13-0515 
  2. Kalra S, Sahay R. Diabetes fatigue syndrome. Diabetes Therapy. 2018;9(4):1421-1429. doi:10.1007/s13300-018-0453-x 
  3. Kalra S, Sahay R. Diabetes Fatigue Syndrome. Diabetes Ther. 2018;9(4):1421-1429. doi:10.1007/s13300-018-0453-x
  4. Penckofer S, Quinn L, Byrn M, Ferrans C, Miller M, Strange P. Does glycemic variability impact mood and quality of life?. Diabetes Technol Ther. 2012;14(4):303-310. doi:10.1089/dia.2011.0191
  5. Wong H, Singh J, Go RM, Ahluwalia N, Guerrero-Go MA. The Effects of Mental Stress on Non-insulin-dependent Diabetes: Determining the Relationship Between Catecholamine and Adrenergic Signals from Stress, Anxiety, and Depression on the Physiological Changes in the Pancreatic Hormone Secretion. Cureus. 2019;11(8):e5474. Published 2019 Aug 24. doi:10.7759/cureus.5474

About the author

Victoria Whittington earned her Bachelor of Science in Food and Nutrition from the University of Alabama and has over 10 years of experience in the health and fitness industry.

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