1. Type 2 Diabetes: Learn the Warning Signs
2. Diabetes and Foot Problems Slideshow
3. Take the Diabetes Quiz!

Medical Author:

Melissa Conrad Stöppler, MD

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.

View Full Profile

Medical Editor:

Jerry R. Balentine, DO, FACEP

Jerry R. Balentine, DO, FACEP

Dr. Balentine received his undergraduate degree from McDaniel College in Westminster, Maryland. He attended medical school at the Philadelphia College of Osteopathic Medicine graduating in1983. He completed his internship at St. Joseph's Hospital in Philadelphia and his Emergency Medicine residency at Lincoln Medical and Mental Health Center in the Bronx, where he served as chief resident.

View Full Profile

In this Article

• Hyperglycemia facts
• What is hyperglycemia?
• What causes hyperglycemia?
• What are the signs and symptoms of hyperglycemia?
• How is hyperglycemia diagnosed?
• How is hyperglycemia treated?
• What are the complications of hyperglycemia?
• Patient Comments: Hyperglycemia - Describe Your Experience
• Hyperglycemia Index

In addition to having elevated levels of glucose in the blood, people with hyperglycemia often have glucose detected in their urine (glycosuria). Ordinarily urine contains no glucose as it is all reabsorbed by the kidneys.

The main symptoms of hyperglycemia are increased thirst and a frequent need to urinate. Other symptoms that can occur with hyperglycemia are headaches, tiredness, blurred vision, hunger, and trouble with thinking or concentrating. Severely elevated glucose levels can result in a medical emergency ("diabetic coma"). This can occur in both people with type 1 and those with type 2 diabetes. People with type 1 diabetes may develop diabetic ketoacidosis (DKA), and those with type 2 diabetes can develop hyperglycemic hyperosmolar nonketotic syndrome (HHNS, also referred to as hyperglycemia hyperosmolar state). These so-called hyperglycemia crises are serious conditions that can be life-threatening if not treated immediately. Hyperglycemic crises cause about 2,400 deaths each year in the U.S.

Over time, hyperglycemia can lead to damage to organs and tissues. Long-term hyperglycemia can impair the immune response, leading to poor healing of cuts and wounds. It can also cause nerve damage, vision problems, and damage to the blood vessels and kidneys (see below).

There are different kinds of blood tests that can diagnose hyperglycemia. These include

• Random blood glucose: this test reflects the blood sugar level at a given point in time. Normal values are generally between 70 and 125 mg/dL, as discussed earlier.
• Fasting blood glucose: this is a measurement of blood sugar level taken in the early morning prior to eating or drinking anything since the night before. Normal fasting blood glucose levels are less than 100 mg/dL. Levels above 100 mg/dL up to 125 mg/dL suggest prediabetes, while levels of 126 mg/dL or above are diagnostic of diabetes.
• Oral glucose tolerance test: this is a test that measures blood glucose levels at given time points after a dose of sugar is consumed. This test is most commonly used to diagnose gestational diabetes.
• Glycohemoglobin A1c: is a measurement of glucose that is bound to red blood cells and provides an indication about blood sugar levels over the past 2 to 3 months.