Fasting Blood Sugar

A fasting blood sugar (FBS) test is used to measure the amount of glucose (sugar) present in your blood after fasting for a whole night or for 8 hours. This test is used to monitor individuals with diabetes. Fasting blood sugar test is the most commonly prescribed test for diabetes and it is the simplest and fastest test.

What is the importance of glucose?

The main source of energy for all the cells in our body, mostly for brain cells comes from glucose. Glucose acts as a building block for carbohydrates. Carbohydrates are commonly found in rice, cereals, bread, fruit, or pasta. Carbohydrates are immediately converted to glucose, thus increasing the glucose levels in your blood. This condition is called diabetes.

Why this test is performed?

This test may be recommended to you if you experience any of the symptoms like increase urge to urinate, blurred vision, recent weight gain, confusion, change in behavior, if you experience seizures for the first time, loss of consciousness, etc. Increase in your blood sugar levels and diabetes may not always show all the symptoms.

Precautions:

Some medicines may also alter your fasting blood sugar levels like contraceptive pills, diuretics like furosemide, torsemide, etc, if you are on hormone therapy, corticosteroids like prednisone, prednisolone, etc, aspirin, phenytoin, lithium, epinephrine, sulfonylurea drugs like glimepiride, glipizide etc, tricyclic antidepressants like amitriptyline, etc.

Inform your doctor about your past illness or medications, about your present illness and current medication prior to the test.

Frequency:

For individuals above 45 years of age, this test is recommended every 3 years. The frequency of this test depends on various factors like body weight, history of heart disease, high blood pressure, gestational diabetes, imbalance of female sex hormones, a family member with diabetes, physically inactive, polycystic ovary disease, etc. Children above 10 years of age with any of two above-mentioned risk factors should be recommended to this test at least once in every 3 years even with no symptoms.

If your fasting blood sugar levels are slightly higher than your normal levels, it may indicate impaired fasting blood glucose which is a type of prediabetes. If it is greater than normal range then it may indicate that you have diabetes.

If your fasting blood sugar levels are lower than normal range then it may indicate a condition called hypoglycemia.

Sometimes other medical problems may also lead to high blood sugar levels like pancreatic cancer, overactive thyroid gland, pancreatitis where pancreas are swollen, stress, trauma, stroke, heart attack, surgery, acromegaly, glucagonoma, pheochromocytoma, Cushing syndrome, etc.

Low level fasting blood sugar may be due to pituitary gland disorder like hypopituitarism, too little food, too much insulin or diabetic medicines, liver disease or kidney disease, underactive adrenal gland or thyroid gland, vigorous exercise, weight loss post surgery, tumor in the pancreas, etc.