Increased thirst, fatigue, and frequent urination are some symptoms of a blood sugar spike. Eating a balanced diet, following your diabetes management plan, and exercising may help prevent spikes.

A blood sugar spike happens when glucose builds up in the bloodstream and your blood sugar levels increase.

Most of the food you eat is broken down into glucose, a type of carbohydrate. Glucose is your body’s primary fuel source and makes your muscles, organs, and brain work properly.

However, glucose can’t be used as fuel until it enters your cells.

A hormone produced by your pancreas called insulin helps unlock cells so glucose can enter them. Without insulin, glucose floats around in your bloodstream with nowhere to go, leading to higher concentrations of glucose.

When glucose builds up in the bloodstream, blood glucose (blood sugar) levels rise. This can lead to hyperglycemia (high blood sugar), which can lead to damaged organs, nerves, and blood vessels.

Blood sugar spikes most commonly occur in people with diabetes because their bodies are unable to use insulin effectively.

Keep reading to learn about the symptoms, causes, and treatment of blood sugar spikes.

Symptoms of hyperglycemia typically begin when blood glucose levels rise above 250 milligrams per deciliter (mg/dL). They can worsen if left untreated.

Symptoms of a blood sugar spike may include:

  • frequent urination
  • fatigue
  • increased thirst
  • blurred vision
  • unexplained weight loss

Some people with diabetes immediately feel the symptoms of high blood sugar, while others don’t because their symptoms are mild or vague.

If your blood sugar stays elevated for too long, you may develop diabetic ketoacidosis.

If high blood sugar levels are untreated for too long, glucose can build up in the bloodstream, starving cells of fuel. Instead, cells will use fat for fuel.

When your cells use fat instead of glucose, the process produces a byproduct called ketones.

If you have unmanaged diabetes, this may lead to diabetic ketoacidosis (DKA), a potentially deadly condition that causes the blood to become too acidic. In DKA, ketone levels are not managed properly due to insulin deficiency.

As such, ketones can rise to dangerous levels quickly and result in diabetic coma or death.

People without diabetes can tolerate certain levels of ketones in the blood, a state known as ketosis. You typically don’t develop ketoacidosis because your body can still use glucose and insulin properly, which helps keep ketone levels stable.

Signs and symptoms of DKA

DKA is a medical emergency that requires immediate treatment. Call 911 or seek emergency medical attention if you experience any of the following symptoms:

  • fruity-smelling breath or sweat
  • nausea and vomiting
  • severe dry mouth
  • trouble breathing
  • weakness and fatigue
  • blurry vision
  • pain in the abdominal area
  • confusion

Symptoms usually develop over 24 hours, but they could happen more suddenly.

Can you have blood sugar spikes and not have diabetes?

Yes, it’s possible for people without diabetes to experience high blood sugar spikes. These usually happen after consuming foods or beverages high in sugar.

The best way to manage high blood sugar is to follow your treatment plan and monitor your levels regularly using a finger stick or a continuous glucose monitor (CGM).

The Centers for Disease Control and Prevention (CDC) recommends the following tips to help you manage high blood sugar:

  • limit your intake of sugary, salty, starchy, and high fat foods
  • exercise regularly
  • eat at regular times daily
  • don’t skip meals
  • drink water instead of sugar-sweetened beverages like soda and juice
  • limit your alcohol intake, if you drink
  • manage stress
  • maintain a healthy-for-you weight

If you frequently experience blood sugar spikes, your doctor may change your medication routine.

If your blood sugar level is repeatedly above 240 mg/dL, check your urine for ketones using a test kit. If you have ketones, don’t exercise, as this could elevate your blood sugar levels.

If ketones are high, call a doctor and seek emergency medical attention immediately.

Blood sugar levels fluctuate throughout the day. When you eat food, particularly foods high in carbohydrates like bread, potatoes, or pasta, your blood sugar immediately begins to rise.

Other causes of blood sugar spikes may include:

  • not following your diabetes management plan
  • not taking enough insulin or using expired insulin
  • insulin not lasting as long as you think it does
  • not getting regular exercise
  • consuming foods and beverages high in sugar, salt, and fat
  • medication dosage needs to be adjusted
  • eating more than usual
  • having an illness or infection
  • experiencing physical or emotional stress, such as injury, surgery, and trouble at work or home

If your blood sugar is consistently high, speak with a doctor about your diabetes management plan.

If your blood sugar is usually well managed but you experience unexplained blood sugar spikes, there might be an acute cause.

Try keeping a record of all the food and drinks you consume. Then, check your blood sugar levels according to your doctor’s recommendations.

It’s common to record your blood sugar reading first thing in the morning, before eating, and 2 hours after eating. Even a few days of recorded information can help you and your doctor learn what’s causing your blood sugar spikes.

There are many ways to prevent blood sugar spikes. Consider adding the following to your diabetes management plan:

  • Work with a nutritionist to develop a meal plan: Planning your meals can help avoid unexpected spikes. You might also want to look at meal planning resources from the American Diabetes Association (ADA).
  • Start a weight loss program, if needed: Losing weight can help your body use insulin better. Talk with your doctor about weight management, and whether they recommend you lose weight to manage your diabetes.
  • Learn how to count carbs: Carb counting helps you keep track of how many carbohydrates you’re consuming. Check out the ADA’s resources on counting carbs and guidebook “Choose Your Foods: Count Your Carbs,” which is available for purchase on the ADA online store.
  • Learn about the glycemic index: Not all carbs are created equal. The glycemic index (GI) measures how different carbs may affect blood sugar. Foods with a high GI rating can affect blood sugar more than those with a lower rating.
  • Find diabetes-friendly recipes or an online meal planning tool: You can try the ADA’s “diabetes plate” method.
  • Measure your portions: A kitchen food scale can help you measure your portions better.
  • Be more active: Exercising regularly can help you manage blood sugar levels. Try going on walks, taking an exercise class, or integrating exercise into activities you already do — like lifting weights while watching TV.
  • Walk after a meal: Walking for 20 minutes after eating a meal may help manage blood glucose levels in people with diabetes.

Occasional blood sugar spikes don’t typically cause complications.

Long-term diabetes complications typically result from having elevated blood sugar levels over a long period of time. Diabetes complications may develop slowly over the course of many years before symptoms appear.

Common complications of unmanaged diabetes and hyperglycemia may include:

Untreated high blood sugar could also develop into ketoacidosis. This is an emergency condition that could lead to diabetic coma or death.

People with diabetes may experience blood sugar spikes because of their body’s inability to use glucose effectively.

Untreated high blood sugar can lead to complications, such as ketoacidosis and conditions that affect the heart, kidneys, eyes, and nerves.

Following your medication routine, regularly testing your blood sugar, and maintaining a balanced diet and regular exercise routine can help you manage blood sugar spikes and reduce the risk of complications in the future.