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Hyperglycemia: What You Should Know About Extreme High Blood Sugar Levels

Medically reviewed by Jezreel Esguerra, MD · General Practitioner

Written by Ira Sagad · Updated Nov 21, 2022

    Hyperglycemia: What You Should Know About Extreme High Blood Sugar Levels

    Hyperglycemia is a condition in which you have high blood sugar levels. It is most commonly linked with diabetes mellitus. But make no mistake; hyperglycemia is common with diabetes, but that does not necessarily mean that you have diabetes. Learn more about the disease as we go along.

    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. Basically, it means that your body cannot utilize insulin properly. So what is insulin? It is a hormone that regulates your blood glucose by pushing glucose into your cells. And since with diabetes, insulin cannot be used by your body, blood sugar level rises as it cannot be regulated properly. This elevation of blood sugar levels is what we call 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.

    Hyperglycemia per se does not equate to diabetes. But it most commonly happens when you have the said disease. As most condition or disease, diabetes produces complications when not managed properly. And these complications can be an emergency.

    The two emergency cases that can result from untreated diabetes are diabetic ketoacidosis and hyperosmolar hyperglycemic syndrome. 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 cannot utilize insulin well are unable to absorb and use glucose. As a result, the body begins to use fat as a source of energy.

    Ketones are a byproduct of fat metabolism, and too much ketones can be harmful to the body. Why? Because ketones can abruptly change the pH level of the blood, making it acidic. This is what happens in diabetic ketoacidosis. Interestingly, patients with type 1 diabetes mellitus will likely develop DKA than patients with type2 diabetes mellitus.

    DKA can present with the following symptoms:

    • 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.

    So 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, which halts further reabsorption of glucose. 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 further 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 such as increased heart rate, dry lips and mouth, 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
    • Low blood pressure
    • 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:

    • 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
    • Acute illnesses such as heart attack

    As mentioned, both DKA and HHS are emergency situations. Fortunately, both conditions are manageable. 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 Takeaways

    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.


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

    Medically reviewed by

    Jezreel Esguerra, MD

    General Practitioner

    Written by Ira Sagad · Updated Nov 21, 2022

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