Low Blood Sugar Emergency: Hypoglycemia Signs, the 15-15 Rule and When to Use Glucagon

Quick answer: low blood sugar, or hypoglycemia, is generally a blood glucose level below 70 mg/dL. The American Diabetes Association’s 15-15 rule says to eat or drink 15 grams of fast-acting carbohydrate, such as 4 ounces of juice or regular soda or glucose tablets, then recheck after 15 minutes and repeat if still low. If someone cannot safely swallow, is unconscious or is having a seizure, do not give food or drink by mouth. Give glucagon if it is available and you know how, place them on their side and call 911.

For people who take insulin or certain diabetes medicines, low blood sugar is one of the most common medical emergencies. It can come on quickly after a missed meal, extra exercise, alcohol or a dose that turned out to be too much. Mild lows are uncomfortable and easy to treat. Severe lows can cause confusion, seizures and loss of consciousness, and the person may not be able to help themselves.

Family members, roommates and coworkers can make a real difference by knowing the signs and the treatment. This guide draws on the American Diabetes Association (ADA), the CDC and the National Institute of Diabetes and Digestive and Kidney Diseases (NIDDK). It is part of our apartment emergency kit guide.

Sources: American Diabetes Association, “Hypoglycemia (Low Blood Glucose)” and the 15-15 rule; CDC, “Low Blood Sugar (Hypoglycemia)” and diabetes emergency preparedness guidance; NIDDK, “Low Blood Glucose (Hypoglycemia)”; FDA information on glucagon products including nasal glucagon; American Red Cross first aid guidance. Checked November 2026. General safety information, not medical advice. People with diabetes should follow the plan from their own health care team.

What Counts as Low Blood Sugar

The ADA and NIDDK describe hypoglycemia in levels:

Level	Blood glucose	What it means
Level 1	Below 70 mg/dL and at or above 54 mg/dL	Low; treat with fast-acting carbohydrate
Level 2	Below 54 mg/dL	Clinically significant low; treat right away
Level 3	Any level with severe confusion or inability to function without help	Severe event requiring help from another person

People without diabetes rarely have dangerous lows. The risk is mainly for people who take insulin or medicines called sulfonylureas, which increase insulin release, according to the NIDDK.

Signs and Symptoms

The CDC lists common symptoms of low blood sugar:

• Shaking
• Sweating
• Nervousness or anxiety
• Irritability or confusion
• Dizziness
• Hunger
• Fast heartbeat
• Blurred vision
• Weakness or tiredness
• Headache

As blood sugar falls further, the person may have trouble speaking clearly, act strangely, become clumsy, have a seizure or pass out. Severe lows can be mistaken for drunkenness, which is one reason a medical ID bracelet matters.

Lows during sleep

Nighttime lows can cause nightmares, sweating through pajamas or sheets, and waking up tired, irritable or confused, according to the NIDDK. Continuous glucose monitors (CGMs) can alarm for lows overnight.

Hypoglycemia unawareness

Some people, especially those who have had diabetes for many years or have frequent lows, stop feeling early warning symptoms. The ADA calls this hypoglycemia unawareness. It raises the risk of severe lows, which makes CGMs and a prepared support network especially useful.

The 15-15 Rule

The ADA’s 15-15 rule is the standard first response for a conscious person who can swallow:

1. Check blood sugar if possible. If you cannot check but symptoms suggest a low, treat anyway.
2. Take 15 grams of fast-acting carbohydrate.
3. Wait 15 minutes and recheck.
4. Repeat if blood sugar is still below 70 mg/dL.
5. Eat a snack or meal once blood sugar is back in range, to keep it from dropping again.

Examples of 15 grams of fast-acting carbohydrate, according to the ADA:

• Glucose tablets (check the label for the right number)
• Glucose gel tube (check the label)
• 4 ounces (half a cup) of juice or regular soda, not diet
• 1 tablespoon of sugar, honey or corn syrup
• Hard candies, jellybeans or gumdrops (check the label for how many)

Avoid foods high in fat or protein, like chocolate or peanut butter, for the first treatment, because fat slows sugar absorption. Children usually need less than 15 grams; follow the plan from their care team.

Do not overtreat

Eating too much during a low can send blood sugar too high later. Sticking to the 15-gram amount and rechecking helps avoid a rebound.

Severe Low Blood Sugar: What to Do

When someone is too confused to eat or drink safely, is unconscious or is having a seizure, treatment by mouth is dangerous because they could choke. The ADA and CDC advise:

1. Do not put food, drink or insulin in their mouth.
2. Give glucagon if it is available and you have been shown how.
3. Turn the person on their side to prevent choking if they vomit.
4. Call 911 if glucagon is not available, if they do not respond within about 15 minutes of glucagon, or if you are unsure what to do.
5. Once awake and able to swallow, give fast-acting carbohydrate followed by a snack.

Types of glucagon

Glucagon is a hormone that raises blood sugar by signaling the liver to release stored glucose. Older kits required mixing powder and liquid in a syringe. The FDA has since approved easier options, including a nasal powder sprayed into one nostril, which works even if the person is unconscious, and prefilled autoinjectors and pens. Ask a doctor or pharmacist which type is prescribed and how to use it.

Glucagon may cause nausea or vomiting when the person wakes, another reason to place them on their side.

Tell everyone where it is

Glucagon only helps if someone else can find it and use it. People at risk for severe lows should keep it in a known place at home, at work, in a bag and in the car (with attention to temperature limits), and show family, roommates or coworkers how to use it. Check expiration dates.

Common Causes of Lows

According to the NIDDK and ADA, lows are often caused by:

• Taking too much insulin, or timing insulin wrong relative to meals
• Skipping or delaying meals
• Eating fewer carbohydrates than planned
• Exercise, which can lower blood sugar during and for hours afterward
• Drinking alcohol, especially without food
• Illness, especially with vomiting or poor appetite

Knowing the cause helps prevent the next one. Note the time, what happened before and how it was treated, and share patterns with the health care team.

Exercise, Alcohol and Lows

Physical activity is one of the most common triggers for a low, and the effect can last well after the workout ends. The ADA notes that exercise makes the body more sensitive to insulin and that blood sugar can drop during activity and for up to 24 hours afterward. People who take insulin are often advised to check blood sugar before, during and after exercise, carry fast-acting carbohydrate and adjust food or insulin as their care team recommends. That advice matters during emergencies too. Carrying supplies up stairs during an outage, shoveling snow or walking long distances after an evacuation all count as exercise, even if they do not feel like a workout.

Alcohol is another important trigger. According to the ADA, alcohol can interfere with the liver’s ability to release stored glucose, which raises the risk of lows, sometimes many hours after drinking and often overnight. The ADA recommends that people with diabetes who drink do so with food and check blood sugar before bed. Friends should know that the symptoms of a severe low, such as slurred speech, stumbling and confusion, can look like intoxication. If someone with diabetes seems drunk, check for a low rather than assuming they just need to sleep it off.

Lows at Work, in Transit and in Public

A low can happen on a subway, in a meeting or at the grocery store. People at risk often keep glucose tablets in several places and let a trusted coworker know what to do. If you see someone who seems confused, sweaty and shaky and they wear a medical ID showing diabetes, ask if they need sugar. If they can swallow, juice or a regular soda from a nearby store can help. When the person cannot respond or is having a seizure, call 911, keep them safe from injury and turn them on their side once the seizure stops.

Transit and building staff are often trained in basic first aid and can call for help quickly. In a high-rise, tell building management about medical needs so they can help during evacuations. Our guide on preparing for a power outage in a high-rise covers that planning. Keep extra supplies in the first aid kit for your apartment too, so glucose tablets and a spare meter are never far away.

Planning for Emergencies and Outages

Disasters, power outages and evacuations can disrupt meals, routines and insulin storage, which raises the risk of both highs and lows. The CDC recommends that people with diabetes keep an emergency kit with:

• At least a week’s supply of diabetes medications and supplies, if possible
• Glucose meter, test strips, lancets, extra batteries and CGM supplies
• Glucose tablets or gel and shelf-stable snacks
• Glucagon
• A cooler and cold packs for insulin
• A written list of medications, doses and providers
• Copies of insurance cards and prescriptions

Insulin should be kept cool. The CDC says unopened insulin can often be kept at room temperature for a limited period, depending on the product, but should not be frozen or left in direct heat. Check the specific insulin’s labeling. Our guides to an emergency medication plan and backup power for medical devices cover storage and charging during outages.

Store glucose where you need it

Low blood sugar can happen anywhere. Small packs of glucose tablets fit in a pocket, purse, desk drawer, nightstand and glove compartment. In a high-rise, keep some in your go-bag in case you are stuck in an elevator or have to walk down many flights of stairs during an evacuation.

After the Low Is Over

Recovery from a low takes time. Even after blood sugar returns to range, people often feel tired, headachy or shaky for a while. The ADA suggests eating a snack or meal once blood sugar is back above 70 mg/dL, especially if the next meal is more than an hour away. After a severe low that needed glucagon or emergency help, the person should contact their health care provider, since the treatment plan or medication doses may need to change. Replace any glucagon that was used and restock glucose supplies right away so they are ready next time.

How Roommates and Family Can Help

People with diabetes often know when something is wrong, but confusion during a low can make them insist they are fine. Agree on a plan in advance:

• Learn the person’s symptoms and their CGM alarms
• Know where glucose and glucagon are kept
• Practice with a glucagon trainer if one is available
• Agree on when to call 911
• Keep emergency contact numbers in phones and on the fridge

A medical ID bracelet or phone emergency profile helps first responders recognize diabetes quickly.

Frequently Asked Questions

What blood sugar level is an emergency?

Below 54 mg/dL is considered a clinically significant low by the ADA. A low at any level with severe confusion, seizure or unconsciousness is an emergency.

What is the fastest way to raise blood sugar?

Fast-acting carbohydrates such as glucose tablets, glucose gel, juice or regular soda. The ADA suggests 15 grams, then recheck in 15 minutes.

Should I give juice to someone who is unconscious?

No. Do not give food or drink to someone who cannot swallow safely. Use glucagon if available, turn them on their side and call 911.

Can glucagon be used by someone without training?

Newer nasal and autoinjector glucagon products are designed to be easy to use, but read the instructions in advance and ask a pharmacist to demonstrate.

Can people without diabetes have low blood sugar?

It is uncommon. Anyone who has low blood sugar symptoms without diabetes should talk to a health care provider.

The Bottom Line

Hypoglycemia is generally blood sugar below 70 mg/dL. For a person who can swallow, follow the 15-15 rule: 15 grams of fast-acting carbohydrate, recheck in 15 minutes, repeat if needed, then eat a snack. For someone who is unconscious, seizing or unable to swallow, give nothing by mouth, use glucagon if available, turn them on their side and call 911. Keep glucose and glucagon where you and others can find them, and plan ahead for outages and evacuations.