High blood sugar: When is it a medical emergency?

Key takeaways

• A blood sugar reading above 250 milligrams per deciliter (mg/dL) is considered very elevated, usually requiring immediate evaluation.
• Symptoms such as extreme thirst, rapid breathing, and confusion can indicate very high blood sugar levels that need prompt medical intervention.
• Lifestyle changes and prescribed medications can help manage high blood sugar, but immediate medical care, including IV insulin, might be necessary during emergencies.

Overview

Hyperglycemia is the medical term for high blood sugar. This refers to blood glucose levels above the optimal range. However, it can refer to anything from slightly higher than optimal to significantly higher.

In some cases, extremely high blood sugar becomes a medical emergency. 

Blood sugar levels are measured using milligrams per deciliter (mg/dL) or millimoles per liter (mmol/L). Doctors often use a blood glucose meter to analyze a small blood sample, typically taken from a finger prick, and determine the glucose concentration in the blood.

Treatment is available and effective for high blood sugar. Timing is key for critical high blood sugar, and emergency medical care is lifesaving.

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Blood sugar levels: What is ‘too high’?

Hyperglycemia is generally defined as blood sugar levels higher than 140 mg/dL, and this should be managed appropriately. Anything above 180 mg/dL needs careful monitoring and attention. Any reading above 250 mg/dL is a symptom of a critical medical emergency known as diabetic ketoacidosis (DKA).

It’s also important to monitor other symptoms you may have. High blood sugar alone may not be a medical emergency, but if you have other symptoms like vomiting, stomach pain, or confusion, then you may need urgent medical care.

A medical emergency means your blood sugar levels may jeopardize your health and life, and you need immediate medical intervention to lower them safely. It is highly advised to go to the emergency room.

Blood sugar ranges

For a healthy adult, the standard range for fasting blood sugar levels (measured after an overnight fast) is generally less than 100 mg/dL. 

However, if you have diabetes, target ranges for blood sugar levels may differ depending on your type of diabetes, age, overall health, and other individual factors. Your healthcare professional may provide you with blood sugar ranges for your case.

According to the World Health Organization (WHO), the expected values for fasting blood glucose in adults are:

• Normal blood sugar: less than 100 mg/dL
• Low blood sugar (hypoglycemia): below 70 mg/dL
• High blood sugar (hyperglycemia): 100 to 125 mg/dL
• Critical high levels: above 250 mg/dL

There are generally no significant differences in blood sugar ranges between males and females, although hormonal fluctuations during the menstrual cycle may temporarily affect blood sugar levels. 

Factors like high carbohydrate foods, stress, and dehydration may also temporarily raise blood sugar levels in both males and females, although individual responses may differ.

Symptoms of high blood sugar

Symptoms of high blood sugar may vary depending on how high they are and for how long. Typically, they may include:

• urinating often
• feeling more thirsty
• unexplained fatigue
• blurred vision
• sudden and persistent headaches

Symptoms of very high blood sugar levels, indicating a medical emergency, may include:

• extreme thirst that does not go away by drinking fluids
• rapid breathing
• heart palpitations
• abdominal pain
• mental confusion or disorientation
• fruity scented breath
• numbness in one or more limbs
• loss of consciousness

Immediate medical assistance is needed for these severe symptoms.

Causes of high blood sugar

Possible causes of persistent high blood sugar may include:

• insufficient insulin production or insulin resistance
• insufficient insulin dosage if you live with diabetes
• untreated or undiagnosed diabetes
• medication side effects, such as those from corticosteroids 
• health conditions like hormonal imbalances or pancreatic disorders
• chronic stress

Persistent high blood sugar may lead to health complications if left untreated. Common complications may include:

• diabetic ketoacidosis (DKA)
• cardiovascular diseases
• nerve damage
• kidney failure
• hyperglycemic hyperosmolar state (HSS)

Can a person without diabetes have high blood sugar levels?

A person without diabetes can have high blood sugar levels.

Causes of high blood sugar without a diagnosis of diabetes may include:

• release of hormones due to high levels of psychological stress
• side effects from certain medications, such as corticosteroids
• pancreatic disorders such as pancreatitis
• menstrual periods, which cause hormonal imbalances 
• dehydration

How quickly can you lower blood sugar levels?

Lowering blood sugar levels quickly may depend on factors like:

• how high your blood sugar is
• whether you live with diabetes or other conditions
• your blood sugar intervention method (insulin shot or oral medication)
• whether the insulin is fast-acting or slow-release
• the cause and duration of your blood sugar spike
• how active you are, as exercise tends to lower blood sugar levels quickly
• your natural body’s response

Generally, a noticeable decrease in your blood sugar levels may take minutes to hours, depending on the above factors and medical intervention.

Medical intervention can lower your levels quickly and safely for significantly high blood sugar.

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How to lower blood sugar levels

During a medical emergency, a healthcare professional may lower your blood sugar levels safely by giving insulin through a vein (intravenous insulin therapy) and replacing fluid and electrolytes via IV.

You can lower your blood sugar levels through medical intervention and lifestyle modifications.

Lifestyle habits like at least 150 minutes of physical activity per week, a nutrient-dense diet, and stress management may help reverse and keep your blood sugar at an optimal level.

If your blood sugar stays high, doctors may prescribe medication to help lower it. Taking the medication exactly as directed is important to keep your blood sugar in a safe range and prevent serious health problems. Always talk with healthcare professionals if you have concerns or side effects.

Common medications used to help lower high blood sugars may include:

Insulin 

Various forms of insulin delivery are available, including rapid-acting, short-acting, intermediate-acting, and long-acting insulin shots.

Some available forms of insulin include:

• Lispro
• Admelog
• Humalog

A doctor may prescribe insulin when other treatment methods, such as oral medications or lifestyle changes, won’t affect your blood sugar levels effectively.

Insulin is a hormone and medication classified as an antidiabetic agent. It helps lower blood sugar levels by promoting the uptake and utilization of glucose by cells. 

Common side effects of insulin may include:

• hypoglycemia
• weight gain
• injection site reactions

The benefits of insulin often outweigh these potential side effects.

Metformin

Metformin (Glucophage) is an oral medication belonging to the biguanide class. It lowers blood sugar by reducing glucose production in the liver and enhancing muscle glucose uptake. 

Common side effects may include: 

• nausea
• vomiting
• diarrhea

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Glipizide

Glipizide (Glucotrol) is an oral medication classified as a sulfonylurea. It stimulates insulin from the pancreas, helping to lower blood sugar levels.  

Common side effects may include:

• hypoglycemia
• weight gain
• nausea

Sitagliptin

Sitagliptin (Januvia) is an oral medication classified as a dipeptidyl peptidase-4 (DPP-4) inhibitor. It helps increase the incretin hormone. This hormone stimulates insulin release and reduces glucagon secretion, which helps lower blood sugar levels.

Common side effects may include:

• upper respiratory tract infections
• headaches

Summary

Extremely high blood sugar — above 250 mg/dL — may lead to severe health challenges and, in some cases, may signal a medical emergency.

Persistent high blood sugar, even if slightly over the optimal range, may also indicate the need for medical intervention. Checking for symptoms like constant thirst, urinating more often, and unexplained fatigue may signal higher-than-optimal blood sugar levels. Consulting with a healthcare professional is highly advised.

Lifestyle changes and, in some cases, medications can help lower high blood sugar and keep it at optimal levels.

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