Doctors carry out this test and use the result to determine whether a person is likely to have diabetes. While other tests may be necessary to confirm a full diagnosis,
This article will look at what a random glucose test is, why a doctor may recommend it, and what the results can mean.
What is random glucose testing?
A random glucose test measures the amount of glucose or sugar in a person's blood.
Random glucose testing measures the levels of glucose in the blood at any given point in the day.
Many blood tests for diabetes involve either fasting or continuous monitoring, but this test does not.
How does the test work?
Glucose is a form of sugar and comes from the foods people eat.
It is the body's primary energy source and fuels every cell, including those in the brain, heart, and muscles.
The body works continuously to keep the amount of blood glucose at optimum levels. It produces a hormone called insulin to achieve this, which helps glucose get into the cells that need it for energy.
People with type 1 diabetes do not produce insulin because their immune systems attack and destroy the cells in the pancreas that make insulin.
People with type 2 diabetes either do not produce enough insulin or their body does not respond to it appropriately.
When a person does not make insulin correctly, glucose remains in the blood. Hyperglycemia occurs when levels remain consistently high and hypoglycemia when they are too low.
Random glucose testing is one way of checking the levels of glucose in the blood. Doctors may carry out a random glucose test at any time of the day.
If the result indicates that a person has higher than expected glucose levels, the doctor will usually order a follow-up test to confirm the diagnosis, including the following:
Fasting glucose test. This test measures blood glucose levels after the person has had nothing to eat or drink for 8 hours.
Doctors usually perform this test in the morning before breakfast.
Oral glucose tolerance test (OGTT). People with diabetes can sometimes demonstrate normal results in the fasting or random glucose tests yet still have diabetes.
If a doctor still suspects that a person has diabetes, they may recommend an OGTT. This test also requires a person not to eat or drink for 8 hours.
After giving the first blood sample, the individual drinks a liquid containing glucose. The doctor then takes more blood samples hourly over the next 2 hours.
Reasons for testing
A doctor may recommend a random blood glucose test if a person shows symptoms of diabetes, such as:
- urinating more often
- feeling extremely thirsty
- feeling very hungry despite eating enough
- unexplained weight loss
- extreme fatigue or tiredness
- blurred vision
- slow healing of cuts and bruises
Type 2 diabetes can often develop slowly, which might make symptoms difficult to detect at first.
People with diabetes may also experience a sensation of tingling or numbness in the hands or feet, or diabetic neuropathy. This is more likely to occur if a person does not control blood glucose for extended periods.
A random glucose test is a quick test that a doctor or nurse can carry out at short notice in their office or clinic. The person does not need to fast beforehand.
The test requires a small sample of blood that the doctor or nurse will take using a needle, often from the finger.
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Doctors measure the amount of glucose in a person's blood in milligrams per deciliter (mg/dL).
For a random glucose test, a result of 200 mg/dL or above indicates that a person may have diabetes. However, for a more reliable diagnosis, the doctor will usually repeat the test on another day.
To help confirm the diagnosis, the doctor may also order a different type of test, such as a fasting glucose test or an OGTT.
For a fasting glucose test:
- less than 100 mg/dL is normal
- 100 to 125 mg/dL indicates prediabetes
- 126 mg/dL or above indicates diabetes
For an OGTT:
- less than 140 mg/dL is normal
- 140 to 199 mg/dL indicates prediabetes
- 200 mg/dL or above indicates diabetes
Prediabetes means that a person's blood glucose levels are higher than usual, but doctors do not yet consider that they have diabetes. Doctors sometimes call this impaired glucose tolerance (IGT) or impaired fasting glucose (IFG).
People with prediabetes are at increased risk of developing diabetes. Lifestyle modifications, such as weight loss and exercise, and certain medications can help reduce this risk.
What can affect the result?
Blood glucose levels change throughout the day, depending on a range of factors.
These might include a person's food intake, as well as the duration and intensity of any exercise or physical activity that day. However, the blood glucose levels of people without diabetes tends to stay within the normal range.
The following factors may increase a person's blood glucose levels:
- eating too much food
- low levels of physical activity
- medication side effects
The following factors may decrease a person's blood glucose levels:
- eating little or no food
- drinking alcohol
- medication side effects
- intense physical activity or exercise
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Diagnosis with any chronic condition can be distressing, and, without treatment, diabetes can lead to serious health problems and complications, including:
However, with effective treatment and management, people with diabetes can enjoy a long and active life.
Doctors usually diagnose type 1 diabetes in children and young adults. People with type 1 diabetes need to take insulin daily and regularly monitor their blood sugar levels for the rest of their lives.
Type 2 diabetes often develops later in life. A person can sometimes manage type 2 diabetes using only diet and exercise. Other people may need medication or even insulin so that they can keep their blood sugar levels within healthy levels.
Anyone with symptoms of diabetes should see their doctor for an evaluation.