Diabetes and Hypoglycemia Unawareness
DiabetesType 1 Diabetes

What Is Hypoglycemia Unawareness?

What Is Hypoglycemia Unawareness?
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Published on December 5, 2025
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If you have type 1 diabetes or type 2 diabetes that you manage with insulin, you could be at risk of hypoglycemia unawareness.

The condition can happen when you use insulin or other diabetes medications, such as or sulfonylureas, that create a risk of low blood sugar (hypoglycemia). After repeated bouts of hypoglycemia, you may stop experiencing the symptoms of low blood sugar, leaving you without a warning to act. If left untreated, hypoglycemia unawareness can lead to dangerous or even life-threatening complications.

Why the Body’s Warning System Fails

The body has a built-in alarm system for hypoglycemia, which occurs when blood sugar drops below 70 milligrams per deciliter (mg/dL).

 It’s triggered by the autonomic nervous system, which sends you into fight-or-flight mode when you sense danger. Typically, this reaction includes the release of adrenaline, which may cause some of the defining symptoms of low blood sugar, such as rapid heartbeat, shaking, sweating, and anxiety.

But when you have hypoglycemia unawareness, your body may not recognize that danger or produce those symptoms.

“It basically means that your autonomic alarm system for low blood sugar is not responding as it normally should,” says Eric Hames, MD, a family medicine physician at Texas Health Harris Methodist Hospital Alliance and a member of the Texas Health Physician’s Group in Fort Worth.

Normally, if your blood sugar drops below 70 mg/dL, you experience physical and neurological symptoms. These symptoms may vary depending on how low your blood sugar is.

Mild hypoglycemia, a blood sugar barely below 70 mg/dL, may cause symptoms that include:

  • Cold or clammy skin
  • Headache
  • Hunger
  • Nervousness
  • Pounding heartbeat
  • Shaking
  • Sweating
Your hypoglycemia is considered moderate if it is less than 55 mg/dL, but it is still a dangerous condition at this level. Additional symptoms include:

  • Confusion
  • Dizziness
  • Irritability
  • Sleepiness
  • Trouble speaking
  • Weakness
When your hypoglycemia is severe, below 40 mg/dL, it is a medical emergency. You may lose consciousness and the ability to swallow, and it can become difficult or impossible to treat your low blood sugar without help from others. Severe symptoms include:

Risks and Complications

Hypoglycemia unawareness can have serious consequences. While people with diabetes can generally sense and treat most episodes of low blood sugar, hypoglycemia unawareness can make it so that symptoms do not appear until the situation is already severe. In those cases, it may be too late for you to treat your own condition the normal way, by eating or drinking something sugary. You may be unable to recognize the danger, or you may lose consciousness entirely. If you’re alone, or not close to anyone who knows that you have diabetes, your situation could quickly become life-threatening.

Hypoglycemia unawareness can easily lead to accidents while driving, working with power tools, swimming, or engaging in similar scenarios that can lead to injuries to yourself or to others.

There is also a long-term risk. Repeated hypoglycemia can lead to brain or heart issues.

Just one episode of severe hypoglycemia may more than double your risk of heart disease, heart failure, or a stroke.

Even if you don’t experience dangerously low blood sugar, the inability to treat hypoglycemia when it is only mild might lead to more frustrating glucose-management issues. If you overcorrect low blood sugar by consuming too many carbohydrates you can rebound into high blood sugar (hyperglycemia), which has its own symptoms and risks.

Fear of hypoglycemia unawareness itself can affect your quality of life, says Joseph Hsiao, MD, an endocrinologist at Providence St. Joseph Hospital in Orange, California. You might opt out of social activities, avoid driving, or even struggle to get a good night’s sleep.

What Causes Hypoglycemia Unawareness?

Alarms are designed to be used infrequently — that’s how they get your immediate attention. If you hear one going off all the time, you might begin to ignore it.

It’s a similar situation with hypoglycemia unawareness. People who take insulin or sulfonylureas are more prone to experiencing blood sugar drops than those who aren’t on medication.

 And when these dips happen frequently, your body may tune them out, Dr. Hames says.
Over time, your threshold for experiencing symptoms of hypoglycemia can dip lower and lower. Eventually, you might not notice until you are about to pass out.

Experts are still learning about why this happens, but they have some theories.

“The exact mechanism of how hypoglycemia unawareness develops is unknown but may involve alterations in hypothalamic regulation and cortisol secretion,” says Dr. Hsiao, referring to the stress hormone released by the adrenal glands.

How Common Is Hypoglycemia Unawareness?

About 25 percent of people with type 1 diabetes experience hypoglycemia unawareness. It affects between 10 and 15 percent of people with type 2 diabetes who take insulin or sulfonylureas.

How to Manage Hypoglycemia Unawareness

If you have hypoglycemia unawareness, you should be careful to change your diabetes management strategy to reduce your risks. That starts with more frequent blood sugar checks.

“The best way to treat hypoglycemia unawareness would be to monitor blood sugar very closely, ideally with a continuous glucose monitor, which should be an essential part of managing any individual who is on insulin or has a history of hypoglycemia,” Hames says.

Depending on your device, you may be able to turn on a sharing mode that can send low blood sugar alerts to a friend or family member.

You should also talk to your doctor about having the medication glucagon on hand. This emergency drug can raise glucose levels quickly in cases of severe hypoglycemia. People with low blood sugar don’t typically use glucagon on themselves; instead, they train their family members, caregivers, coworkers, or roommates on how to use it in an emergency.

Your doctor or diabetes educator may also have specific advice on how to avoid dangerous hypoglycemia episodes. For example, you may be advised to change your drinking habits or take less insulin before you go to sleep or on days when you plan to exercise.

Lifestyle changes that support stable blood sugar levels will help, too. Have regular meals and snacks that include sources of complex carbohydrates such as whole grains, fruits, vegetables, and beans, Hsiao says.

When your blood sugar levels do fall below 70 mg/dL, take steps to bring them back up — even if you feel fine. Have 15 to 20 grams of fast-acting carbohydrates as soon as possible. A tablespoon of honey, 4 ounces of regular soda or fruit juice, hard candies or jelly beans (check the nutrition label for the serving size), or a glucose gel tube may do the trick. Then wait 15 minutes and check your blood sugar again.

Repeat this process as needed until your blood sugar levels are trending up. Then, have a snack with carbohydrates and protein, such as crackers with cheese or peanut butter, to keep your blood sugar levels from dropping again before your next meal.

How to Improve or Reverse Hypoglycemia Unawareness

There’s no direct cure or treatment for hypoglycemia unawareness, but you may be able to improve your condition by avoiding hypoglycemia. The key to restoring hypoglycemia sensitivity is to keep your blood sugar from dropping into that dangerous low range.

You can potentially benefit from any change that helps keep your blood sugar safe and stable, whether you’re using new blood sugar monitoring technology, a new diet, or a new insulin-dosing strategy. Avoiding episodes of low blood sugar over just the course of a few weeks can recalibrate your body’s alarm system.

 Work closely with your doctor on a diabetes management plan that significantly reduces your incidence of hypoglycemia without frequently provoking high blood sugar levels.
Though it may be impossible to restore your sensitivity fully, any improvement could reduce your risk of dangerous outcomes and make your daily diabetes management easier and less stressful.

The Takeaway

  • Hypoglycemia unawareness is a dangerous condition that occurs when you have diabetes and your blood sugar is too low but your body does not recognize the symptoms.
  • If your blood sugar is too low, you may have a seizure or lose consciousness, and repeated bouts of hypoglycemia can cause brain and heart issues.
  • You may need to change your diabetes management strategy to minimize the risks, particularly by checking your blood sugar more frequently.
  • It may be possible to restore your sensitivity to low blood sugar by avoiding hypoglycemic events as much as possible.

Resources We Trust

EDITORIAL SOURCES
Everyday Health follows strict sourcing guidelines to ensure the accuracy of its content, outlined in our editorial policy. We use only trustworthy sources, including peer-reviewed studies, board-certified medical experts, patients with lived experience, and information from top institutions.
Resources
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  5. How Hypoglycemia Unawareness Affects People With Diabetes. National Institute of Diabetes and Digestive and Kidney Diseases. April 5, 2023.
  6. Echouffo-Tcheugui J et al. Severe Hypoglycemia, Cardiac Structure and Function, and Risk of Cardiovascular Events Among Older Adults With Diabetes. Diabetes Care. November 16, 2020.
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Anna L. Goldman, MD

Medical Reviewer
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Anna L. Goldman, MD, is a board-certified endocrinologist. She teaches first year medical students at Harvard Medical School and practices general endocrinology in Boston.

Dr. Goldman attended college at Wesleyan University and then completed her residency at Icahn School of Medicine at Mount Sinai Hospital in New York City, where she was also a chief resident. She moved to Boston to do her fellowship in endocrinology at Brigham and Women's Hospital. She joined the faculty after graduation and served as the associate program director for the fellowship program for a number of years.

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