What are your concerns?

Hard to understand

Or copy link


Hyperglycemia: What You Should Know About Extreme High Blood Sugar

Hyperglycemia: What You Should Know About Extreme High Blood Sugar

Hyperglycemia is a condition in which you have high blood sugar levels. Most cases of hyperglycemia have a link with diabetes mellitus, therefore, in most cases, these terms may be used interchangeably.

Diabetes and Hyperglycemia

Diabetes mellitus is a metabolic disorder that occurs when the body does not produce enough insulin or there is high insulin resistance. Insulin is a hormone that regulates your blood glucose by pushing glucose into your cells. And once these problems with insulin occur, blood sugar cannot be regulated. This can lead to elevated blood sugar levels, or hyperglycemia.

The criteria for hyperglycemia are as follows:

  • Random blood glucose of more than or equal to 200mg/dl, together with clinical symptoms such as increase in appetite, increased thirst, and increase in urine output
  • Fasting blood glucose of more than or equal to 126mg/dl
  • 2-h plasma glucose ≥200 mg/dl following a 75-g oral glucose challenge in adults

When Hyperglycemia Is Not Controlled

Hyperglycemia, when controlled, is typically a benign condition. However, certain events can push the body into glucose dysregulation. These cases can be life-threatening, especially when intervention is delayed.

The two emergency cases that can result from an elevated blood glucose are diabetic ketoacidosis and hyperosmolar hyperglycemic syndrome. These happen when blood glucose levels reach 250mg/dl. Let’s talk about each of them briefly.

Diabetic Ketoacidosis

Diabetic ketoacidosis, or DKA, is an acute, serious condition that can happen to people with uncontrolled hyperglycemia when substances called “ketones” accumulate in their blood.

Under normal circumstances, the body uses glucose to produce energy. However, people with diabetes who do not usually have enough insulin are unable to absorb and use glucose. As a result, the body begins to metabolize fat as a source of energy.

Ketones are a byproduct of fat metabolism, and too much ketones can be harmful to the body. DKA is more likely to develop in patients with type 1 diabetes mellitus.

DKA can present as:

  • Nausea or vomiting
  • Fatigue
  • Generalized weakness
  • Abdominal pain
  • Decrease in appetite
  • Increased urination
  • Altered mental status
  • Fruity breath

Hyperosmolar Hyperglycemic Syndrome

Hyperosmolar hyperglycemic syndrome or HHS, on the other hand, usually evolves over several days to weeks, in contrast to DKA that develops within a 24-hour period. In addition, HHS is more common in patients with type 2 diabetes mellitus. Unlike in DKA, patients with HHS do not have elevated ketone bodies in their blood.

What happens in HHS? Under normal circumstances, all of the glucose that goes through the kidneys is reabsorbed back into the body. When the blood glucose level reaches approximately 180mg/dl, the blood becomes saturated with glucose, and further reabsorption is halted. The glucose that remains in the kidney is therefore excreted in the urine. This increases the saturation of urine, and a signal is sent to the kidneys to increase water excretion to reverse the supersaturation. Because of the increase in water excretion, glucose concentration in the blood increases, leading to severe hyperglycemia.

Because of an increase in urination, patients with HHS are more severely dehydrated than patients with DKA. They may show signs of dehydration upon presentation, such as increased heart rate, dry lips and oral mucosa, sunken eyes, and decreased skin turgor. Other signs and symptoms of HHS include:

  • Dark yellow or brown urine
  • Weight loss
  • Increase in urination
  • Increased thirst or water intake
  • Hypotension
  • Weak pulse
  • Altered mental status
  • Lethargy

What Leads to Hyperglycemia?

A particular event that abruptly increases blood glucose levels usually precedes both DKA and HHS. The most common precipitating events leading to DKA and HHS include:

  • Acute illnesses such as heart attack and stroke
  • Infections such as pneumonia and urinary tract infection
  • Abrupt discontinuation of insulin therapy
  • Inadequate insulin therapy
  • Decrease in water intake
  • Intake of drugs that affect carbohydrate metabolism, such as glucocorticoids, diuretics, and antipsychotics
  • Cocaine use
  • Eating disorders and other problems that may lead to insulin omission
  • Malfunction of continuous subcutaneous insulin infusion (CSII) devices

As mentioned, both DKA and HHS are emergency situations. Fortunately, both conditions are reversible. Patients with hyperglycemia suspected of having DKA or HHS must be brought to the nearest hospital for prompt evaluation and intervention. Appropriate treatment for both conditions includes strict glucose monitoring and control, fluid resuscitation, and treatment of the underlying condition.

Key Takeaway

Severe hyperglycemia can lead to life-threatening conditions. Consult with your doctor to learn how to prevent this from happening.

Learn more about Diabetes here.

Living with diabetes?

You're not alone. Join the Diabetes community and share your stories and experiences. Join Community now!

Hello Health Group does not provide medical advice, diagnosis or treatment.


Hyperosmolar Hyperglycemic Syndrome, https://my.clevelandclinic.org/health/diseases/21147-hyperosmolar-hyperglycemic-syndrome, Accessed October 21, 2021

Diabetic hyperosmolar syndrome, https://www.mayoclinic.org/diseases-conditions/diabetic-hyperosmolar-syndrome/symptoms-causes/syc-20371501, Accessed October 21, 2021

Hyperglycemia (High Blood Glucose), https://www.diabetes.org/healthy-living/medication-treatments/blood-glucose-testing-and-control/hyperglycemia , Accessed October 21, 2021

Hyperglycemia, https://www.ncbi.nlm.nih.gov/books/NBK430900/, Accessed October 21, 2021

Hyperglycemia, https://medlineplus.gov/hyperglycemia.html, Accessed October 21, 2021

Picture of the authorbadge
Written by Ira Sagad Updated Nov 15, 2021
Fact Checked by Vincent Sales