All forms of diabetes, including prediabetes, type 1, type 2, and gestational diabetes, can be diagnosed and tracked with the help of a diabetes blood test.
Blood glucose units: Basically, there are two measurement units in use for blood glucose measurement; they are:
- Milligrams per deciliter (mg/dl) unit measures milligrams (mg) of glucose per deciliter (dL) of blood. The blood glucose level in mg/dl is the unit used in the United States.
- Millimoles per liter (mmol/L) is a unit measuring the millimoles (mmol) concentration of glucose per liter (L) of blood. Most of the world (except the United States) uses this unit.
What is a diabetes test?
A diabetes test is a simple blood test used to diagnose or monitor diabetes. It measures the glucose or sugar level in the plasma or blood.
- Fasting plasma glucose (FPG) test: The FPG test measures glucose level after fasting for at least 8 hours. This test is useful to detect all types of diabetes. For the FPG test, you must have been fasting for at least 12 to 14 hours (must not eat or drink anything except water for 12 to 14 hours). Thus, this test is convenient to carry out in the morning.
- Oral glucose tolerance test (OGTT): The OGTT measures blood glucose after 8 hours of fasting and 2 hours after the person drinks a glucose-containing beverage.
- Random plasma glucose test - It is also called a casual plasma glucose test; it does not require fasting or worrying about what we have eaten. This test with symptom assessment is used to diagnose diabetes but not pre-diabetes. However, once a random plasma glucose test is confirmed, diabetes needs to be reconfirmed by FPG or OGTT.
- Glycated hemoglobin A1C test: This HbA1C test does not require fasting or the need to drink anything and can be taken at any time at your convenience. This test provides the mean blood glucose level for the last 2 to 3 months. Thus, helps assess, how well or worse your diabetes treatment is responding.
What is the fasting blood sugar test?
Fasting triggers a glucagon hormone when there is no longer enough glucose in the blood for energy. The pancreas produces glucagon hormone that instructs the liver to convert stored glycogen to glucose and release it into the bloodstream for energy requirements.
Once the liver releases glucose into the bloodstream, the healthy body responds quickly by releasing insulin to prevent hyperglycemia (high blood glucose). However, for diabetics, there is insufficient insulin secretion or improper use of available insulin, thus glucose levels stay elevated.
What is Oral glucose tolerance?
The oral glucose tolerance test assesses the body's ability to tolerate the consumption of a certain amount of glucose. Specifically, it measures the body's ability to use blood glucose. OGTT provides details about how quickly glucose is absorbed from the bloodstream. The test is carried out after one hour and two hours of having a glucose beverage say 75mg.
What is a Random blood glucose test?
The Random blood glucose test assesses the blood sugar level at any time of the day. No fasting is required and no worry about what you have eaten.
A level of 200 mg/dl or higher is an indication of diabetes. Additional tests such as fasting blood glucose, oral glucose tolerance test, and or a1c test are required to confirm diabetes diagnosis.
Even if the results are within the normal range, your doctor may order additional tests if you have diabetes risk factors or symptoms.
Also, if the test result confirms diabetes at the borderline level, then the doctor may order another test on another day to reconfirm diabetes.