Hyperglycemia (High Blood Sugar): Symptoms & Signs

  • Medical Author:
    Melissa Conrad Stöppler, MD

    Melissa Conrad Stöppler, MD, is a U.S. board-certified Anatomic Pathologist with subspecialty training in the fields of Experimental and Molecular Pathology. Dr. Stöppler's educational background includes a BA with Highest Distinction from the University of Virginia and an MD from the University of North Carolina. She completed residency training in Anatomic Pathology at Georgetown University followed by subspecialty fellowship training in molecular diagnostics and experimental pathology.

Hyperglycemia is the term that refers to an abnormally high level of sugar, or glucose, in the blood. Diabetes mellitus types 1 and 2 are by far the most common causes of hyperglycemia. In patients with either type 1 or type 2 diabetes, metabolic abnormalities lead to an elevation in blood glucose levels. When there is too much glucose in the blood, this can lead to a number of health risks and other symptoms. The main symptoms associated with hyperglycemia are

A severe elevation in blood glucose level can be life-threatening. This represents a medical emergency like diabetic ketoacidosis (DKA) or hyperglycemic hyperosmolar nonketotic syndrome (HHNS, also referred to as hyperglycemic hyperosmolar state). Some symptoms of hyperglycemia occur when the hyperglycemia is present for a long time, such as poor wound healing and weight loss. In emergencies like diabetic ketoacidosis, symptoms include nausea, vomiting, abdominal pain, confusion, shortness of breath, and a fruity odor to the breath.

Causes of hyperglycemia

Type 1 or type 2 diabetes is the most common cause of hyperglycemia. Other causes can include pancreatitis, Cushing's syndrome, unusual hormone-secreting tumors, pancreatic cancer, certain medications, and severe illnesses.


Kasper, D.L., et al., eds. Harrison's Principles of Internal Medicine, 19th Ed. United States: McGraw-Hill Education, 2015.

Medically Reviewed by a Doctor on 3/6/2017

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