Hyperglycemia is a term referring to high blood glucose levels - the condition that often leads to a diagnosis of diabetes.
High blood glucose levels are the defining feature of diabetes, but once the disease is diagnosed, hyperglycemia is a signal of poor control over the condition.
Hyperglycemia is defined by certain high levels of blood glucose:1
- Fasting levels greater than 7.0 mmol/L (126 mg/dL)
- Two-hours postprandial (after a meal) levels greater than 11.0 mmol/L (200 mg/dL).
Chronic hyperglycemia usually leads to the development of diabetic complications.2
Symptoms of hyperglycemia
The most common symptoms of diabetes itself are related to hyperglycemia - the classic symptoms of frequent urination and thirst.2,3
Hyperglycemia is defined as having a fasting blood glucose level greater than 126 mg/dL.
Typical signs and symptoms of hyperglycemia that has been confirmed by blood glucose measurement include:1,3,4
- Thirst and hunger
- Dry mouth
- Frequent urination, particularly at night
- Recurrent infections, such as thrush
- Weight loss
- Vision blurring.
Causes of hyperglycemia
Hyperglycemia often leads to the diagnosis of diabetes. For people already diagnosed and treated for diabetes, however, poor control over blood sugar levels leads to the condition. Causes of this include:1,3,4
- Eating more or exercising less than usual
- Insufficient amount of insulin treatment (more commonly in cases of type 1 diabetes)
- Insulin resistance in type 2 diabetes
- Illness such as the flu
- Psychological and emotional stress
- The "dawn phenomenon" or "dawn effect" - an early morning hormone surge.
The video below from Diabetes UK explains the dawn phenomenon and offers practical tips.
Treatment and prevention of hyperglycemia
Prevention of hyperglycemia for people with a diabetes diagnosis is a matter of good self-monitoring and management of blood glucose levels, including adherence to insulin regimes if necessary.4
For someone who has not been diagnosed with diabetes, symptoms of hyperglycemia need to be reported to a doctor so that they can test for diabetes - other conditions can also lead to hyperglycemia.4
Control of high blood sugar is important to prevent complications caused by chronic hyperglycemia. A doctor may need to review the treatment plan for a diabetes patient who becomes hyperglycemic and they may decide to take one of the following actions: 4
- Raise the insulin dose (learn more about insulin treatment)
- Recommend dietary changes (learn more about diet and diabetes)
- Recommend more exercise (learn more about exercise and diabetes)
- Recommend closer glucose monitoring (learn more about self-monitoring).
Hyperglycemia can lead to diabetic ketoacidosis
It is important to attend to hyperglycemia since it can lead to a dangerous complication known as ketoacidosis that can result in coma and even death. Ketoacidosis rarely occurs in type 2 diabetes, typically occurring in cases of type 1 diabetes.3
High levels of glucose in the blood mean that insufficient levels of glucose are available to cells for their energy needs. As a result, the body resorts to breaking down fat so that energy is derived from fatty acids. This breakdown produces ketones, leading to higher acidity of the blood.2,3
Diabetic ketoacidosis requires urgent medical attention and, alongside hyperglycemia and its symptoms, is signaled by:2,4
- Nausea or vomiting
- Abdominal pain
- A fruity smell on the breath
- Drowsiness or confusion
- Loss of consciousness.
Hospital treatment of ketoacidosis includes the administering of intravenous fluids and insulin.2