High Blood Sugar Emergency: Hyperglycemia, DKA Warning Signs and What to Do

Quick answer: high blood sugar (hyperglycemia) can become an emergency when it leads to diabetic ketoacidosis (DKA), a dangerous buildup of acids called ketones. Warning signs include extreme thirst, frequent urination, nausea or vomiting, stomach pain, fruity-smelling breath, deep or fast breathing, weakness and confusion. If someone with diabetes has these symptoms with high readings or moderate to large ketones, call their healthcare provider or emergency services right away. If the person is confused, very drowsy, vomiting repeatedly or breathing hard, call 911. Follow the person’s own diabetes care plan, and do not guess at insulin doses.

Most people hear about low blood sugar emergencies, but high blood sugar can also become life-threatening, especially for people with type 1 diabetes, and it can happen during illness, missed insulin doses, pump failures or stress. Knowing the signs and having a plan can make the difference in an emergency, including during a storm or power outage when insulin storage and supplies become a challenge. This guide is part of our emergency first aid guide. It explains what to look for, what to do and how to prepare. It is general information and does not replace medical advice from a person’s diabetes care team.

Sources: American Diabetes Association (ADA) information on hyperglycemia, ketones and DKA; Centers for Disease Control and Prevention (CDC) diabetes and DKA resources; National Institute of Diabetes and Digestive and Kidney Diseases (NIDDK); Mayo Clinic patient information on diabetic ketoacidosis. Target ranges and action thresholds differ by person, so use the plan from the person’s healthcare provider. In an emergency, call 911 or your local emergency number.

What High Blood Sugar Is

Hyperglycemia means there is too much sugar (glucose) in the blood. In people with diabetes, it happens when the body does not have enough insulin or cannot use insulin well. Causes can include:

• Missed or too little insulin or diabetes medicine
• Illness or infection
• Eating more carbohydrates than planned
• Less physical activity than usual
• Stress, injury or surgery
• Certain medicines, such as steroids
• Problems with an insulin pump or an infusion site
• Insulin that was exposed to heat or has expired

A single high reading is common and often handled at home with the plan from a healthcare provider. The concern is a persistent high, or high readings with symptoms and ketones.

Symptoms of High Blood Sugar

Early signs often include:

• Increased thirst and dry mouth
• Frequent urination
• Blurred vision
• Tiredness
• Headache
• Unplanned weight loss over time

These symptoms can develop slowly. If blood sugar stays high for hours or days, the body may start breaking down fat for fuel, which makes ketones.

What DKA Is

Diabetic ketoacidosis happens when the body does not have enough insulin to let glucose into cells, so it burns fat instead. This produces ketones, which are acids. When ketones build up, the blood becomes too acidic. DKA is most common in type 1 diabetes, but it can occur in type 2 diabetes in some situations. It can also be the first sign that someone has diabetes.

Warning Signs of DKA

• Nausea, vomiting or stomach pain
• Fruity-smelling breath, which comes from ketones
• Fast, deep breathing
• Flushed face
• Extreme thirst and very dry mouth
• Frequent urination
• Weakness or fatigue
• Confusion, trouble concentrating or unusual sleepiness
• High blood sugar readings, often above 250 mg/dL, though DKA can occur at lower numbers in some situations, such as with certain medicines

DKA can develop within hours to a day or more, and children and teens can get sick quickly. Early action is important.

When to Check Ketones

Many diabetes care plans advise checking ketones when blood glucose is high, often above 240 mg/dL, or during illness, even if sugars are not very high. Ketone test strips for urine or meters for blood ketones are available over the counter or by prescription. Your provider can tell you which type is suitable, what the numbers mean and when to call.

General guide (follow your own plan):

Ketone result	Typical meaning	What to do
Negative or trace	Little or no ketones	Continue your plan and recheck if sick or high
Small	Early ketones	Drink fluids, follow your plan and recheck
Moderate or large	Risk of DKA	Call your provider or emergency services right away

Your care team may use different numbers, especially for blood ketone meters, so always use the thresholds they gave you.

First Aid: What to Do

If blood sugar is high but the person feels well

• Check blood glucose and ketones if indicated.
• Drink water or sugar-free fluids to stay hydrated.
• Take insulin or medicine as prescribed in the care plan. Do not guess at doses or give extra insulin without guidance.
• Avoid heavy exercise if ketones are present, since it can make blood sugar and ketones go up.
• Recheck in a couple of hours, or as directed.
• Call the healthcare provider if levels stay high.

If DKA is suspected

1. Call emergency services (911) if the person is confused, very drowsy, vomiting repeatedly, breathing fast or deeply, or has severe stomach pain.
2. Stay with the person and keep them calm.
3. Check blood sugar and ketones if you can, without delaying the call.
4. Give sips of water if they are awake and able to swallow and are not vomiting.
5. Do not give insulin or other medicine unless directed by the care plan or emergency staff.
6. If unconscious, place them on their side if breathing and be ready to start CPR if they stop breathing. Our guide to shock first aid describes how to support someone who is very ill.
7. Give information to responders: diabetes type, recent blood sugar and ketone readings, insulin or medicine taken and any recent illness.
8. Bring supplies such as the insulin, meter and medical ID to the hospital.

DKA is treated in a hospital with fluids, insulin and monitoring of electrolytes.

High Blood Sugar vs. Low Blood Sugar

Telling these apart can be hard. If you are not sure and the person is conscious and able to swallow, check blood sugar. When you cannot check, a person who is shaky, sweaty, confused and has a history of diabetes medicines may be low, and quick sugar is the usual first step. Our guide to low blood sugar emergencies explains how to treat a low. If the person has fruity breath, fast deep breathing and long-lasting symptoms, high blood sugar is more likely. When in doubt, call 911.

Sick Day Rules

Illness raises the risk of high blood sugar and DKA, even when a person is not eating much. Many diabetes care plans include sick day rules such as:

• Keep taking insulin, even if you cannot eat. Ask your provider how to adjust doses.
• Check blood sugar more often, such as every few hours.
• Check ketones if sugar is high or you are sick.
• Drink plenty of fluids, and sip sugar-containing drinks if blood sugar is low.
• Call your provider if you have vomiting, diarrhea, fever or cannot keep fluids down.
• Keep emergency numbers and the care plan handy.

Dehydration makes everything worse, so learn the signs in our guide to dehydration signs and first aid.

Preparing for Emergencies and Power Outages

Storms, outages and evacuations can make diabetes care harder.

• Keep a supply of medications, test strips, ketone strips, lancets and insulin, according to guidance from the provider and the pharmacy.
• Store insulin properly. Unopened insulin is usually kept in the refrigerator, while opened insulin has a shorter shelf life at room temperature. Check the label and the manufacturer’s directions for the specific type. If power is out, follow manufacturer guidance for how long insulin can be safely kept at room temperature.
• Use a cooling case or a cool, insulated bag for insulin if you need to leave.
• Charge devices such as meters, pumps and phones, and see our guide on backup power for medical devices during outages.
• Wear a medical ID or carry a card with diabetes type, medicines, allergies and emergency contacts.
• Pack a go-bag with supplies, snacks for lows, copies of prescriptions and the care team’s contact details.
• Keep a backup plan such as syringes if a pump fails.
• Talk to your provider about a written emergency plan.

A basic kit is a good starting point, and our guide to a first aid kit for a small apartment lists items to stock.

Insulin Pump Problems

People who use insulin pumps depend on a steady flow of rapid-acting insulin. If a pump stops working, a tube kinks or an infusion site comes loose, blood sugar can climb quickly because there is no long-acting insulin in the body. Warning signs of a pump problem include unexplained high readings, a pump alarm or leaking at the site. Most pump training teaches the same steps: check the site and tubing, change the infusion set if there is any doubt, check ketones and follow the plan for a correction dose with an injection if the pump may have failed. Keep spare pump supplies and a backup supply of insulin, along with syringes or pens, in your go-bag.

High Blood Sugar in Children and Teens

Children can develop DKA quickly, especially when they are sick or when their first symptoms of diabetes are missed. Parents should watch for increased thirst, bedwetting in a child who was previously dry, weight loss, unusual tiredness, stomach pain and fast breathing. Because symptoms can look like a stomach bug or the flu, any child with known diabetes who is vomiting needs a ketone check. A child who has these signs and has never been diagnosed with diabetes should be seen by a doctor the same day, and an emergency room visit is appropriate if the child is breathing fast, is very sleepy or has been vomiting.

Another Serious Condition: Hyperosmolar State

Most people hear about DKA, but older adults with type 2 diabetes can develop a different emergency called hyperosmolar hyperglycemic state. In this condition, blood sugar becomes extremely high over days, causing severe dehydration, confusion, weakness and sometimes seizures, often without ketones or fast breathing. It tends to develop slowly during illness or when someone cannot drink enough. Any person with very high readings, strong thirst and confusion needs emergency care.

Questions to Ask the Care Team

• What blood sugar number should make me call you?
• When should I check ketones, and what do the results mean?
• How much insulin or medicine should I take on sick days?
• What should I do if my pump fails?
• How should I store insulin during a power outage?
• Do any of my medicines raise the risk of DKA?
• What should be in my emergency kit?

Write down the answers and keep them where you and the people in your home can find them quickly.

Who Is at Higher Risk?

• People with type 1 diabetes, including children and teens
• People who miss insulin doses or have trouble affording supplies
• People with an insulin pump, if the pump or infusion site fails
• People who are ill, have infections or are under severe stress
• People taking certain medicines, such as some newer diabetes medicines called SGLT2 inhibitors, which can occasionally cause DKA at lower blood sugars. Ask your provider about this.

How to Help Someone With Diabetes

• Encourage them to follow their care plan and to speak up if they feel sick.
• Learn the warning signs and where their supplies are kept.
• Know who to call and the person’s provider contact information.
• Do not assume symptoms are only from the flu or stress.
• Stay calm and clear when speaking with emergency dispatchers.

After the Emergency

After an episode of high blood sugar or DKA, the care team will review what caused it. They may adjust medicine, review insulin technique, check supplies and teach sick day steps. Ask questions, and make a plan for next time.

Frequently Asked Questions

What blood sugar level is an emergency?

There is no single number for everyone. Very high readings with symptoms or moderate to large ketones, and symptoms like confusion or vomiting, need urgent care. Follow your provider’s plan.

What does DKA breath smell like?

Often fruity or like nail polish remover, caused by ketones. Not everyone has it, so do not rely on the smell alone.

Should I give insulin if I find someone with a high blood sugar?

Only if their care plan directs it. Guessing at doses can be dangerous. If they are unwell, call their provider or 911.

Can DKA happen with type 2 diabetes?

Yes, though it is less common. It can happen during serious illness or with certain medicines.

How can I prepare for a power outage with diabetes?

Keep supplies and a plan, know how to store insulin without refrigeration, charge devices ahead of time and ask your provider for a written emergency plan.