A blood glucose test, also known as a blood sugar test, a fasting blood sugar, or random blood sugar, is a measurement of the number of glucose molecules in your bloodstream at any given moment.
What is glucose?
Glucose is the form of sugar that the cells in your body use for energy, and its presence in your blood is regulated by the hormone insulin. When there is a lot of glucose circulating in your blood, your body releases more insulin hormone to help bring glucose molecules from the bloodstream into your cells. These molecules can then be used as fuel (for cells like muscle cells), or they may be stored in fat cells.
When you have diabetes, your body’s cells are not as sensitive to the effects of insulin, or your body may not be producing insulin at all, so there is a greater amount of glucose that remains in your bloodstream, notes Medline Plus. Continuously high blood glucose levels can damage your body over time, causing kidney problems, vision problems, nerve problems, and heart problems, among many others. For this reason, medical professionals use a blood glucose test to check for high levels of sugar in the blood and screen for diabetes or monitor the status of existing diabetics. Other medical conditions can also cause a high blood glucose level such as problems with your adrenal glands, according to the National Library of Medicine (NLM).
What is a glucose test?
A blood glucose test can also reveal low blood glucose levels. Low blood glucose levels can cause severe symptoms such as seizures or comas according to the NLM. It may sound contradictory, but people who have diabetes can also suffer from low blood sugar levels, especially if they use insulin injections to help manage their blood sugar. Low blood sugar levels may also be caused by other medications or health conditions according to the NLM.
Who should get a glucose test?
A blood glucose test can be a useful tool for anyone who is having symptoms of high or low blood sugar. According to the NLM, symptoms of high blood sugar can include excessive thirst or hunger, having wounds that don’t heal well, fatigue, unintentional weight loss, blurred vision, or numbness or tingling in your extremities. According to the US Centers for Disease Control and Prevention (CDC), symptoms of low blood sugar can include hunger, dizziness, irritability, confusion, anxiety, sweating, or shaking.
Your healthcare provider may also use a blood glucose test as a screening tool for diabetes. This can be especially helpful if you have the following risk factors for type 2 diabetes, as noted by the CDC:
- Excessive body weight
- Age greater than 45
- A family history of diabetes
- High blood pressure
- Sedentary lifestyle
- Heart disease
- A history of gestational diabetes
Additionally, the CDC states that a blood glucose test can help you monitor your blood sugar if you already have a diagnosis of prediabetes or diabetes. Many people who have diabetes are well-accustomed to checking their blood glucose several times a day to see how well their body is processing glucose and make interventions as needed.
How to get a glucose test
There are many ways to get a blood glucose test. At-home blood glucose monitors are available over the counter without a prescription; however, many insurance companies will also pay for these machines (and their associated lancets and testing strips) if you have an order from a healthcare provider. A healthcare provider can also perform a blood glucose test in a clinic setting, using either a finger stick or a blood draw. A finger stick method can give you immediate results, whereas the results of a blood draw may take longer because they are processed by a laboratory. Another way in which you can monitor your own blood sugar is through a medical device known as a continuous glucose monitor (CGM). These machines can be a valuable substitute for finger pricks if you have a health condition that requires you to frequently check your blood sugar.
What to expect during a glucose test
What you can expect during a blood glucose test may vary depending on the context according to the NLM. If you are at a health clinic and your healthcare provider recommends a blood glucose test, you may have a blood draw or finger prick on the spot. Or, if your healthcare provider would like for you to be fasting before your blood glucose test, you may be requested to return at a later time to have this simple blood test. If you are pregnant or have another specific medical need, your healthcare provider may order a specific type of blood glucose test known as an oral glucose tolerance test (OGTT). According to the NLM, these tests require you to consume a large amount of sugar and then have your blood drawn within a certain time frame to see how well your body processes sugar.
Interpreting the results of a glucose test
When you are interpreting the results of a glucose test, it will be important to factor in the setting in which you took the test. A sugar level can have different meanings depending on whether or not you were fasting when you had the test performed.
According to the CDC, for a fasting blood sugar test, the following ranges are considered standard:
- Normal: 99 mg/dL or below
- Prediabetes: 100 mg/dL to 125 mg/dL
- Diabetes: 126 mg/dL or above
According to the CDC, a glucose test can be used to diagnose prediabetes or diabetes. If you are not fasting and your blood sugar is greater than 200mg/dL, this is also considered to be a result consistent with diabetes if you are also having symptoms of high blood sugar.
What to do if a glucose test is elevated
The CDC reports that if you have an elevated blood glucose test, it could mean that you have either prediabetes or diabetes. If you are pregnant, it may mean that you have gestational diabetes. Other factors can contribute to high blood sugar at a specific moment in time, including certain medications, so talk with your healthcare provider about an abnormal blood glucose test to decide what steps you need to take. A healthcare provider may suggest further testing, lifestyle changes, medications, or any of these measures in combination, to help you lower your blood glucose and avoid the consequences of consistently high blood sugar levels.
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Glucose Testing FAQs
What is a glucose test looking for?
A glucose test checks for the amount of blood glucose that is in your bloodstream at the time of the assessment. This is usually measured in milligrams per deciliter. This test can fluctuate based on whether or not you have eaten food before the test, notes the CDC.
Does a high glucose test mean I have diabetes?
A high glucose test could mean that you have diabetes, according to the CDC. These tests diagnose diabetes in people who are fasting or in people showing signs of hyperglycemia (high blood sugar). However, blood sugar could be high outside of diabetes, so follow-up is needed if you have an elevated test.
What kind of diabetes do I have if my glucose test is elevated?
If you have Type 1 diabetes, Type 2 diabetes, or gestational diabetes, your blood glucose can be elevated, reports the CDC. However, a blood glucose test cannot decipher between types of diabetes. A healthcare provider can help you determine the type of diabetes that is causing an elevated test.
How often should I get my glucose test checked?
According to the CDC, you may benefit from a blood glucose check every 3 years if you are aged 45 and above and have had previous tests with a normal range. If you have prediabetes or diabetes, talk to your healthcare provider about how often to check your blood glucose.
Can your glucose test result change?
Yes, glucose tests provide a snapshot of your blood glucose level at a very specific point in time (the point at which your blood is assessed). Your blood glucose levels are dynamic and they fluctuate naturally throughout the day. This means that your blood glucose test result will also change.
Where can I get a glucose test?
How can I lower my glucose test?
According to the American Diabetes Association (ADA), exercising is one of the best ways to lower your blood glucose. Consult your physician prior to starting an exercise program.
Are there risks of getting a glucose test?
Yes, a finger prick or blood draw can cause slight bruising or bleeding. Rarely, there is a chance of infection—however, this is not common, notes the ADA. Overall, the risks of getting a blood glucose test are very low.
Solv has strict sourcing guidelines and relies on peer-reviewed studies, academic research institutions, and medical associations. We avoid using tertiary references.
- Blood Glucose Test (Jul 07, 2022)
- Manage Blood Sugar (Sep 30, 2022)
- Oral Glucose Tolerance Tests: What Exactly Do They Involve? (Oct 22, 2020)
- Hyperglycemia (High Blood Glucose) (2022)
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