High blood sugar is known as “hyperglycemia,” and it can be dangerous for people with or without diabetes. Hyperglycemia can cause drowsiness, thirst, and a need to urinate more often.

Acute hyperglycemia is also known as “elevated blood glucose (BG) levels.” While hyperglycemia is most commonly thought of in the context of diabetes, there are other conditions that may lead to hyperglycemia.

This article will explain more about acute hyperglycemia, the conditions that may play a part in its development, how serious a health concern it may be, and how you can treat it with a healthcare team’s consultation.

Acute hyperglycemia happens when a person experiences severe or intensely elevated BG levels.

Hyperglycemia indicates high blood sugar, and it’s measured as a BG level:

  • more than 125 milligrams per deciliter (mg/dL) when you haven’t eaten for at least 6 hours (fasting)
  • more than 180 mg/dL 2 hours after eating (postprandial)

Hyperglycemia in someone who doesn’t have diabetes may be an indication of medical distress or undiagnosed diabetes.

Higher glucose levels for someone with diabetes could reflect poorly managed BG and indicate the need for a direct treatment response.

Everyone’s glucose levels vary throughout the day.

Generally glucose levels rise in response to eating food or experiencing stress, illness, or injury, or with some medications. If your glucose levels rise too high consistently, the risk of more serious and even life threatening complications is increased.

The most immediately dangerous of these complications is diabetic ketoacidosis (DKA), which is a medical emergency. DKA can happen in all types of diabetes but is typically experienced by people with type 1 diabetes.

When DKA happens, the blood’s chemical balance can change dramatically, which may lead to a coma and even death. DKA is suspected when glucose levels reach and stay at 300 mg/dL or above. Testing blood or urine for the presence of ketones will confirm a DKA diagnosis.

Symptoms of DKA may include:

  • abdominal pain
  • fruity breath
  • extreme thirst
  • increased urination
  • fatigue
  • hunger

If hyperglycemia evolves from acute to chronic, more serious complications are possible. Chronic hyperglycemia may affect or damage your brain, heart, kidneys, and nerves.

Diabetes disrupts the body’s ability to produce and effectively use its insulin to moderate and maintain BG levels. Because of its effect on BG levels, hyperglycemia is commonly thought about in the context of diabetes.

There are two main mechanisms in diabetes that drive hyperglycemia:

  • when the body doesn’t secrete enough insulin
  • when the body is insulin resistant and doesn’t effectively use the insulin it does produce

The first mechanism is most commonly associated with type 1 diabetes but can happen with type 2 diabetes as well.

The second mechanism, insulin resistance, is associated with type 2 diabetes. It’s important to note that regardless of type, diabetes does increase the risk of experiencing hyperglycemia.

The signs and symptoms of hyperglycemia can vary. How strongly these symptoms are experienced may also vary from person to person.

Symptoms of hyperglycemia include:

  • drowsiness or feeling tired
  • excessive thirst
  • excessive urination
  • blurred vision

Additional symptoms that are associated with DKA (extreme hyperglycemia that can create a medical emergency) include:

  • fruity smelling breath
  • dry mouth and dry skin
  • frequent urination that lasts a day or more
  • mental confusion or difficulty concentrating
  • feeling weak
  • nausea or vomiting
  • abdomen pain

Some people don’t experience symptoms or aren’t aware they’re having symptoms even though their glucose levels are elevated. Unawareness can be risky because the person may end up experiencing DKA without realizing it, which can be life threatening.

Over time, as hyperglycemia becomes more chronic, elevated glucose levels can damage blood vessels throughout the body, including blood vessels in the brain that carry oxygen-rich blood to the brain. Once blood vessels in the brain are damaged, brain cells can die off due to receiving too little blood.

The resulting cerebral (or brain) atrophy can undermine memory and mental abilities. Over time cerebral atrophy can also lead to dementia.

Yes, hyperglycemia can result from stress, infections, and taking some medications.

This kind of nondiabetic hyperglycemia is more common in people who are critically ill. It’s especially more common for people in the hospital receiving intravenous (IV) nutritional support than for people not receiving an IV.

Nondiabetic hyperglycemia can also happen in children.

In a 2020 review of clinical research literature on the issue of medication-induced hyperglycemia in children, the authors found that certain medications are associated with a higher risk of hyperglycemia in both kids and adults:

  • corticosteroids (such as hydrocortisone, prednisone, and dexamethasone)
  • L-asparaginase
  • tacrolimus

Other medications may also lead to hyperglycemia, but the level of risk is less clear:

  • clonidine
  • hormonal contraceptives
  • amiodarone

Experiencing physical or psychological stress can drive BG levels up and result in hyperglycemia. This is true for people without diabetes as well as those who have diabetes.

A diagnosis of stress-induced hyperglycemia (SIH) results from an illness that either lowers the amount of insulin the body secretes or triggers insulin resistance.

Generally measured as a BG level of more than 180 mg/dL in people without diabetes, SIH is usually temporary.

Regardless, SIH should still be monitored and managed to minimize the chance of experiencing hyperglycemia complications.

Additionally, a number of other health ailments can lead to experiencing hyperglycemia, including:

When to seek medical care

If DKA is suspected you should seek medical care immediately, by calling 911 or local emergency services, because DKA can be life threatening.

How you may recognize DKA:

  • If your BG level readings are 240 mg/dL or higher in a row with or without any DKA symptoms.
  • If you check for ketones, which can initially be checked by an at-home urine test strip, and find the presence of a large number of ketones.
  • If BG levels are above 300 mg/dL, you may need to go to the emergency room.
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Bringing BG levels down is the first priority in treating hyperglycemia.

Often for people with diabetes, there are a number of actions that can be taken in response to a hyperglycemic episode. While physical exercise and drinking water can help, insulin has the most direct effect on BG levels.

If you know your “correction factor” (the number of units of insulin needed to lower your BG level by a certain amount), determine the dose and take a shot of insulin. Check for changes to your BG level 20 to 30 minutes after taking the dose. If you don’t see any change in BG levels after 2 hours, you may want to take a second dose of insulin.

Be careful not to “stack” insulin doses and end up with extremely low BG levels (hypoglycemia, measured as less than 70 mg/dL). Clinicians advise you to wait at least 3 hours before taking additional insulin to avoid overlapping doses.

Seek medical care up front if you feel uncertain about how much insulin to take in response to hyperglycemia. If you come to a point in a hyperglycemic episode when you aren’t sure what to do next, seek medical care.

Seek medical care immediately if your BG levels remain above 300 mg/dL, you experience DKA symptoms, or you have measurable ketones using an at-home test.

Managing daily BG levels is the cornerstone of managing diabetes. By keeping BG levels within a healthy range (typically 70 to 180 mg/dL), the risk of developing complications is reduced.

Hyperglycemic episodes drive BG levels well outside the healthy range. Each episode brings with it the risk of long-term complications. At its most extreme, when DKA results, hyperglycemia can be life threatening.

It’s imperative that people with diabetes continually and actively manage their BG levels. To do this requires a daily regimen of insulin injections (for insulin users), a healthy diet, regular exercise, and stress management.

Acute hyperglycemia poses serious danger, especially to those living with type 1 diabetes. It’s important to recognize the signs and take corrective action when a hyperglycemic episode happens, which reduces the likelihood of developing physical and mental complications over time.