Fasting blood glucose

Fasting Blood Glucose

Fasting blood glucose (FBG) is a test that measures the level of glucose in the blood after an individual has not eaten for at least 8 hours. It is commonly used to diagnose and monitor diabetes mellitus, as well as to assess the risk of developing diabetes.

Physiology

Glucose is a primary source of energy for the body's cells. It is obtained from the food we eat and is regulated by hormones such as insulin and glucagon. After a meal, blood glucose levels rise, prompting the pancreas to release insulin, which helps cells absorb glucose. During fasting, insulin levels decrease, and the liver releases stored glucose to maintain normal blood glucose levels.

Procedure

The fasting blood glucose test is typically performed in the morning after an overnight fast. A healthcare professional will draw a blood sample, usually from a vein in the arm. The sample is then analyzed in a laboratory to determine the glucose concentration.

Interpretation of Results

The results of a fasting blood glucose test are interpreted as follows:

• Normal: FBG level less than 100 mg/dL (5.6 mmol/L)
• Prediabetes: FBG level between 100 and 125 mg/dL (5.6 to 6.9 mmol/L)
• Diabetes: FBG level of 126 mg/dL (7.0 mmol/L) or higher on two separate tests

Clinical Significance

Fasting blood glucose is a critical component in the diagnosis and management of diabetes. It helps in:

• Diagnosing Diabetes: Along with other tests such as the oral glucose tolerance test (OGTT) and hemoglobin A1c, FBG is used to diagnose diabetes.
• Monitoring Diabetes: Regular FBG tests help in monitoring the effectiveness of diabetes management strategies.
• Assessing Risk: Elevated fasting blood glucose levels can indicate an increased risk of developing type 2 diabetes and cardiovascular diseases.

Factors Affecting Fasting Blood Glucose

Several factors can influence fasting blood glucose levels, including:

• Diet and Nutrition: High carbohydrate intake can lead to elevated glucose levels.
• Physical Activity: Regular exercise can help lower blood glucose levels.
• Medications: Certain medications, such as corticosteroids, can increase blood glucose levels.
• Stress and Illness: Stress and acute illnesses can cause temporary increases in blood glucose levels.

Also see

• Diabetes mellitus
• Insulin
• Oral glucose tolerance test
• Hemoglobin A1c
• Hypoglycemia