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When You Don’t Know You’re Low – Hypoglycemia Unawareness 101

Most people with diabetes know when they are low, but others have difficulty detecting it or are completely unaware. This is known as hypoglycemia unawareness.

People with hypoglycemia unawareness or “impaired hypoglycemia awareness” can't tell when their blood sugar gets low, which can put them at a higher risk for severe episodes of hypoglycemia.

Let's break down what hypoglycemia unawareness is, what factors increase the likelihood of experiencing it, and the steps you can take to reduce your risk.

What is impaired awareness of hypoglycemia?

Hypoglycemia can be caused by too much insulin, missing a meal without reducing medication, exercise, alcohol, and other factors. Also known to increase the risk of hypoglycemia are sulfonylureas, a medication used to treat type 2 diabetes. 

Hypoglycemia unawareness occurs when someone doesn’t experience or perceive the symptoms of hypoglycemia, which typically occur when blood sugars fall below 54 mg/dl (3.0 mmol/L). 

Studies show that those with hypoglycemia unawareness are at much higher risk for experiencing severe hypoglycemia as they are less likely to recognize early “alert” signs, which stem from the body’s natural response to very low blood sugar. 

Early warning signs of low blood glucose levels commonly include shakiness, hunger, and sweating. Other symptoms of hypoglycemia include:

  • Confusion

  • Dizziness

  • Difficulty speaking

  • Heart palpitations

  • Headache

  • Muscle weakness

  • Nausea

  • Sleepiness

  • Clumsiness or jerky movements 

Risk factors for hypoglycemia unawareness

An estimated one in five people with type 1 diabetes and one in ten with insulin-treated type 2 diabetes report experiencing hypoglycemia unawareness.

Several factors increase this risk, including:

  • Going low while sleeping. Many people experience low blood sugar levels while they are asleep and not able to perceive the symptoms or treat the low. If this happens frequently, it can affect the ability to detect hypoglycemia warning symptoms while awake.

  • Exercise. The likelihood of hypoglycemia is increased both during and after exercise, when the body’s tissues are more sensitive to insulin. This effect can be delayed and occur up to 15 hours later, especially if the amount of exercise was unusually strenuous.

  • Having diabetes for a long time. Studies have found that people with diabetes who have used insulin over many years are more likely to develop hypoglycemia unawareness compared to those on insulin for fewer years. This may be because people who've had diabetes for longer are more likely to have experienced multiple episodes of hypoglycemia, which has been shown to contribute to hypoglycemia unawareness.

  • Age. As many people get older, they start to experience changes in cognition like slowed thinking, confusion, and difficulty speaking. These cognitive symptoms can occur at the same time as low blood sugar symptoms, making hypoglycemia hard to distinguish. There is no exact age when this effect begins to take place, as the process of aging varies so widely. However, some studies indicate that hypoglycemia unawareness occurs more frequently in people over age 60.

  • Consuming alcohol. Too much alcohol, in the short term, can lower your ability to recognize typical symptoms. It also impairs your liver’s ability to release glucose when blood sugar levels drop too low. These effects typically last as long as it takes your body to process the alcohol. There is no evidence that alcohol increases hypoglycemia unawareness long-term unless chronic, heavy drinking leads to permanent liver damage. That, in turn, increases the risk of severe hypoglycemia.

  • Certain prescription drugs. Non-selective beta-blockers used to manage high blood pressure, like Inderal (see here for a complete list), may reduce your ability to recognize hypoglycemia. Selective serotonin reuptake inhibitors (SSRIs) used to treat depression may also have this effect. Common SSRIs include Lexapro, Prozac, and Zoloft.

Do I have hypoglycemia unawareness?

Below is a questionnaire to determine if you have hypoglycemia unawareness: 

If you recognize hypoglycemia only when glucose is far below 54 mg/dL (3.0 mmol/L), consider taking steps (more on that below) to reduce the number of times your blood glucose falls below this level. This may also help to reset the onset of symptoms or recognition of a higher glucose level.

What can I do to protect myself?

Here are some of the best tips for avoiding hypoglycemia unawareness.

1. Measure blood sugar more frequently

Measure your blood sugar several times daily using finger sticks or continuous glucose monitoring (CGM). By doing this, those with impaired awareness can identify potential hypoglycemia and reduce the risk of falling low without warning.

2. Continuous glucose monitoring

A number of clinical trials have shown that seeing your glucose levels in real-time (via measuring tissue fluid) may help prevent hypoglycemia.

While fingersticks give a snapshot at a single point in time, CGM provides a glucose value every five minutes, as well as trend information and optional alarms, alerting users of lows when they start or even before they happen.

Studies have found that CGM reduces hypoglycemia in people taking insulin who have hypoglycemia unawareness. In another study, CGM use showed a 58% reduction in severe hypoglycemic episodes. Research has found CGM to be significantly more effective than finger sticks in reducing hypoglycemia, though it's important to note that not everyone has access to these devices as they can be costly and are only available in certain countries.

A full list of continuous glucose sensors currently available in the U.S. and Europe can be found here.

3. Fine-tune your insulin regimen

FDA-cleared apps like iSage Rx and My Dose Coach may also be helpful for people with type 2 diabetes who would like more frequent guidance for dosing basal insulin.

If possible, switch to an insulin analog or next-gen insulin – especially one of the newest long-acting (basal) insulin analogs like Toujeo or Tresiba.

  • Common basal insulin analogs include Basaglar and Lantus.

  • Next-generation insulins associated with less nighttime hypoglycemia include Toujeo and Tresiba.

  • If possible, avoid using older, less predictable insulins like NPH (also called “N”).

  • Fast-acting (mealtime) insulin analogs include Humalog, NovoRapid/Novolog, Apidra, and Fiasp. Another option is the inhaled insulin Afrezza, an ultra-rapid-acting product that some users have reported a lower risk of delayed hypoglycemia.

Access can be challenging – work with your healthcare provider, and see our various strategies to gain coverage in the U.S. through our access series.

For people with type 2 diabetes on insulin therapy, taking a GLP-1 agonist may reduce the need for boluses (mealtime insulins), which may reduce hypoglycemia. Common GLP-1 drugs include Victoza, Ozempic, Trulicity, and Bydureon. It's a good idea to consult with your healthcare provider before making any changes to your insulin regimen.

4. Structured training

Structured training is in-person training with a doctor, nurse, or diabetes educator who will help on how to improve insulin use and anticipate an increased risk of low blood sugar. They also help manage mental barriers associated with going low.

If you have never worked with a certified diabetes educator, it is especially encouraged. You can use this online tool from the American Association of Diabetes Educators to find a program near you.

Medicare and most private insurance plans cover up to 10 hours of initial training with a diabetes educator, although people covered by Medicare have to pay 20% of the session’s cost. This free, online training also provides general information on how to recognize and treat hypoglycemia.

5. Automated insulin delivery

Similar to CGM, automated insulin delivery (AID) is technology designed to remove constant monitoring and decision-making to help users manage blood sugars.

AID systems take CGM values every few minutes and run them through algorithms that decide how much insulin to deliver via a pump. As blood sugars fall, insulin is reduced or suspended, which helps prevent hypoglycemia.

Newer AID systems available for users in the U.S. include the MiniMed 780G, Omnipod 5, and Tandem Mobi. Many people with diabetes are also using do-it-yourself AID systems, such as Loop and OpenAPS.

6. Build a hypoglycemia emergency toolkit

A great way to combat hypoglycemia unawareness is to have an emergency toolkit with all the items you need in case you do go low. It’s important to make sure that friends and family members know what to do in case you have a hypoglycemic event and that they know where your emergency toolkit is.

Your emergency kit should include: glucose tablets or sugary snacks, glucagon (either emergency nasal glucagon like Baqsimi or ready-to-use autoinjector pens like the Gvoke HypoPen), a glucose monitor (this could be a BGM or CGM), and emergency contact information.

Glucagon is an extremely important part of anyone’s toolkit. Glucagon is a hormone that increases blood sugar levels by telling the cells in the body to release any stored sugar into the bloodstream. In an emergency, glucagon can be given to someone to quickly raise their blood glucose. 

The bottom line

While impaired awareness of hypoglycemia can be a serious issue for some people with diabetes, the risk can be significantly reduced with the right tools, resources, and awareness. 

Sometimes hypoglycemia unawareness is unavoidable, but taking steps like making adjustments to your insulin regimen, measuring blood sugar often, and using a CGM are all ways to prevent low blood glucose.

Learn more about managing low blood sugar here: