Hypoglycemia unawareness, also known as impaired awareness of hypoglycemia (IAH), is one of the most alarming and dangerous issues that people with diabetes can face. Normally, a drop in glucose levels triggers warning symptoms (like shaking or sweating) that prompt you to treat the low. In hypoglycemia unawareness, these warning signals are diminished or absent, so you might not realize you’re low until your thinking, coordination, or behavior is already impacted.

The good news: awareness can improve for many people. This page explains what hypoglycemia unawareness is, why it happens, how to recognize it, and practical steps to reduce risk—especially overnight.

What is hypoglycemia unawareness (impaired awareness of hypoglycemia)?

Impaired awareness of hypoglycemia means you don’t notice the usual early symptoms of low blood sugar, or you only notice them when glucose levels are already very low. Sometimes you may check a number that is clearly low and still feel “fine,” or feel too confused to act quickly.

This matters because early symptoms serve as your natural safety alarm. Without them, lows are more likely to become serious and may require assistance from someone else.

Why it’s not a “willpower” problem

Hypoglycemia impacts the brain. When the brain isn’t getting enough fuel, insight and judgment can decline. That’s why people may deny they’re low, refuse treatment, or act in ways that are out of character.

Why is hypoglycemia unawareness dangerous?

IAH is closely linked to severe hypoglycemia. If you don’t feel a low coming on, you might continue driving, exercising, working, or sleeping while your glucose keeps dropping. Unless someone else notices what’s happening—or your CGM alarm wakes you—serious outcomes (like seizures or loss of consciousness) can occur.

Action step: If you’ve ever needed help from someone else for a low, consider that a major safety signal. Contact your diabetes clinician promptly to review your insulin and medication plan.

What causes hypoglycemia unawareness?

The most common cause is repeated hypoglycemia. Frequent lows can “train” the body to respond less strongly—reducing the stress hormone response that usually triggers warning symptoms and helps raise glucose. Over time, lows may start to seem less severe… until they become serious.

Common triggers that can impair awareness

Frequent recent lows (especially over the past 1–3 days)
Overnight lows (many people sleep through them)
Longer duration of diabetes (risk increases over time for many people)
Rapid drops (glucose falling quickly can outpace your ability to notice)
Alcohol within the last 12 hours (increases risk of delayed lows, especially overnight)
Exercise and increased activity can boost insulin sensitivity for hours.
Some medications, such as beta-blockers, can hide warning signs like tremor or rapid heartbeat.
Stress, burnout, depression, or low capacity for self-care (missed checks, missed snacks, dosing errors)

In type 1 diabetes, another factor is that the normal glucagon response to falling glucose levels is often diminished over time, which can further raise the risk, emphasizing the importance of prevention and early detection.

How frequently do people experience impaired awareness of hypoglycemia?

Estimates vary based on how it’s measured and who is studied. In type 1 diabetes, impaired awareness is frequently reported in a significant minority of people (often estimated at up to approximately 40% in some studies and reviews). Among older adults with type 1 diabetes, the rates may be even higher. People with IAH have a significantly increased risk of severe hypoglycemia.

If you’re not sure whether this applies to you, treat it like a screening question: “Do I ever have lows without feeling them?” If yes, it’s worth addressing—even if severe lows haven’t happened yet.

What are the signs that you might have hypoglycemia unawareness?

You don’t need a formal diagnosis to recognize this. Common signs include:

You find that glucose is low (<70 mg/dL), but you have few or no symptoms.
You often find yourself “suddenly realizing’ you’re very low instead of noticing early symptoms.
Others notice personality changes, confusion, or clumsiness before you do.
You experience nighttime lows (alarms don’t wake you, or you wake up feeling ‘foggy’).
You’ve experienced a serious low (needed help, passed out, or had a seizure)

Can hypoglycemia unawareness be reversed?

Often, yes—at least partly. A common recommended approach is a period of strict avoidance of hypoglycemia. The goal is to give your body time to “reset” and re-learn early warning signals. Some people notice improvement within a few weeks, with further progress as lows become less frequent.

How can you restore awareness of low glucose?

Use this as a practical plan to discuss with your clinician. You don’t have to do everything at once—small changes can make a big difference.

1) Temporarily raise targets (intentionally)

For a brief period (usually 1–3 weeks), set safer targetsand try to avoid lows altogether.
This may include a higher CGM low alert and an earlier “urgent low soon” style alert, if available.

2) Decrease the frequency of lows—especially following a low.

After any significant low, be extra cautious during the next 24–48 hours.
Check more often, avoid aggressive corrections, and be conservative with activity and alcohol.

3) Use CGM alerts and share alarms when appropriate

If you’re at risk, a CGM is one of the most effective tools for prevention—especially overnight.
Think about sharing alerts with a partner or family member if you tend to sleep through alarms.

4) Review insulin settings (basal, carb factor, correction factor)

Frequent lows often indicate that insulin settings are too aggressive for your current needs.
Review patterns based on time of day (overnight, after meals, after exercise).
Make incremental changes with clinical guidance.

5) Use AID features strategically (if available)

Use exercise or activity modes when suitable.
Be careful with late corrections and stacking insulin.
If your levels are often low, consider whether targets, insulin action time, or settings need adjusting.

What steps can you take to stay safe while working on awareness?

Have a “severe low” plan (and supplies)

Keep fast carbs in multiple locations (bedside, car, desk, pocket).
Ask your clinician about glucagon. Today, there are easier-to-use options (including nasal and ready-to-use injectables) besides traditional kits.
Show others what to do if you can’t self-treat.

Driving Safety

If you have impaired awareness, consider treating driving as a higher-risk activity.

Check your glucose before driving and on long trips.
Don’t drive if you are low or if your glucose is rapidly dropping.
Keep fast carbs accessible (not in the trunk).

When is it necessary to contact your clinician?

Contact your diabetes clinician promptly if:

You’ve experienced a severe low (needed help from someone else).
You suspect impaired awareness (low levels without symptoms)
You are experiencing frequent lows (for example, more than 1–2 per week).
You’re waking up with low readings or suspecting overnight lows.

You aren’t “failing” if this occurs. It typically indicates that your insulin or medication plan needs updating to reflect real-life conditions.

Awareness can improve—begin by avoiding lows.

Hypoglycemia unawareness is common enough that many people experience it at some point, especially with long-term diabetes and frequent lows. The best approach is usually simple: avoid hypoglycemia for a while, use CGM/AID tools and safer targets, and work with your clinician to adjust insulin settings so lows become less frequent. As lows decrease, warning signs often become clearer again—making life safer and less stressful.

Other Resources

Medical disclaimer: This content is for education and does not replace individualized medical advice. Seek urgent help for severe lows (seizure, unconsciousness, or inability to swallow safely), and talk with your clinician if you’re having frequent or unexplained hypoglycemia.

Last Updated on December 31, 2025

Contents hide

1 What is hypoglycemia unawareness (impaired awareness of hypoglycemia)?

1.1 Why it’s not a “willpower” problem

1.2 Why is hypoglycemia unawareness dangerous?

2 What causes hypoglycemia unawareness?

2.1 Common triggers that can impair awareness

3 How frequently do people experience impaired awareness of hypoglycemia?

4 What are the signs that you might have hypoglycemia unawareness?

5 Can hypoglycemia unawareness be reversed?

6 How can you restore awareness of low glucose?

6.1 1) Temporarily raise targets (intentionally)