A blood glucose test measures the glucose levels in your blood. Glucose is a type of sugar. It is your body's main source of energy. A hormone called insulin helps move glucose from your bloodstream into your cells.
Too much or too little glucose in the blood can be a sign of a serious medical condition. High blood glucose levels (hyperglycemia) may be a sign of diabetes, a disorder that can cause serious, long-term health conditions.
High blood sugar may also be caused by other conditions that can affect insulin or glucose levels in your blood, such as problems with your pancreas or adrenal glands.
Low blood glucose levels (hypoglycemia) are common among people with type 1 diabetes and people with type 2 diabetes who take certain diabetes medicines. Certain conditions, such as liver disease, may cause low levels of blood glucose in people without diabetes, but this is uncommon. Without treatment, severe low blood sugar can lead to major health problems, including seizures and brain damage.
Other names: blood sugar, self-monitoring of blood glucose (SMBG), fasting plasma glucose (FPG), fasting blood sugar (FBS), fasting blood glucose (FBG), random blood sugar, glucose challenge test, oral glucose tolerance test (OGTT)
A blood glucose test is used to find out if your blood sugar levels are in a healthy range. It is often used to help diagnose and monitor diabetes.
Your health care provider may order a blood glucose test if you have symptoms of high glucose levels or low glucose levels.
Symptoms of high blood glucose levels include:
Symptoms of low blood glucose levels include:
You may also need a blood glucose test if you have a high risk for developing type 2 diabetes. You're more likely to develop diabetes if you:
If you are pregnant, you will likely get a blood glucose test between the 24th and 28th week of your pregnancy to check for gestational diabetes.
