Fasting glucose, or fasting glucose, is a blood test that measures the rate of glucose in the bloodstream and needs to be done after a fasting of 8 to 12 hours without consuming any food or drink except water .
This test is widely used to investigate the diagnosis of diabetes, and to monitor the blood sugar levels of people who are diabetic or at risk for this disease.
In addition, to obtain more reliable results, this test may be requested in conjunction with others who also evaluate these changes, such as the oral glucose tolerance test (TTOG) and glycated hemoglobin, for example. Learn more about the tests that confirm diabetes.
Reference values
The reference values for fasting blood glucose are:
- Normal fasting glycemia: less than 110 mg / dL;
- Altered fasting glycemia: between 110 mg / dL and 125 mg / dL;
- Diabetes: equal to or greater than 126 mg / dL;
- Low fasting glycemia or hypoglycemia: equal to or less than 70 mg / dL.
To confirm the diagnosis of diabetes, when the glycemic value is equal to or greater than 126mg / dl, it is necessary to repeat the examination the other day, since at least 2 samples are recommended.
When the values of the test are between 110 and 125 mg / dL, it means that the fasting glycemia is altered, that is, the person has a pre-diabetes, a situation in which the disease has not yet been established, but there is an increased risk of developing. Learn more about what is and how to treat pre-diabetes.
Examination of fasting blood glucose in pregnancy is part of the prenatal routine and can be done in any trimester of pregnancy, but the reference values are different. Thus, for pregnant women, when fasting glycemia is above 92 mg / dL, this may be a case of gestational diabetes. However, the main diagnostic test for this condition is the glycemic or TOTG curve. Find out what it means and how the glycemic curve test is done.
Exam Preparation
The preparation of the fasting glucose test includes not taking any food or drink that contains calories for at least 8 hours and should not exceed 12 hours of fasting.
It is recommended to keep your usual diet the week before the test and it is important not to consume alcohol, avoid caffeine and not practice rigorous exercise the day before the test.
Who should do fasting blood glucose
This test is usually asked by doctors to track the presence of diabetes mellitus, a disease that causes increased blood glucose, or to monitor blood glucose levels for those who are already taking the treatment for this disease.
This research is usually done for all people over 45 years, every 3 years, but it can be done on younger people or in less time if there are risk factors for diabetes, such as:
- Symptoms of diabetes, such as excessive thirst, excessive hunger and weight loss;
- Family history of diabetes;
- Sedentary lifestyle;
- Obesity;
- HDL (good) cholesterol low;
- High pressure;
- Coronary disease, such as angina or infarction;
- History of gestational diabetes or childbirth with macrosomia;
- Use of hyperglycaemic medication, such as corticosteroids and beta-blockers.
In cases of altered fasting glycemia or impaired glucose tolerance detected in previous exams, it is also recommended to repeat the examination annually.
