Insulin Fasting is a test that measures insulin levels in the blood after 8 hours of fasting or whole night fasting.
What is Insulin?
Insulin is a hormone produced by the beta cells in the pancreas. Insulin helps in absorption of glucose (sugar) from the bloodstream into the cells of the body. In these cells, glucose is used for the production of energy, which is utilized by the body. In healthy individuals, insulin production is high when the glucose levels in the blood are high and insulin production is low when the glucose levels in the blood are low.
Insulin maintains blood glucose levels and prevents hypoglycemia (low blood sugar levels) as well as hyperglycemia (high blood sugar levels). Insulin converts the excess sugar in the blood into glycogen for storage.
If insulin secretion is abnormal or if the body is unable to produce insulin, it may lead to an increase in the blood sugar levels; this may cause Diabetes mellitus. If the body is unable to produce insulin, it may lead to type 1 diabetes mellitus. If the body produces an insufficient amount of insulin or if the body cells are resistant to insulin, this may lead to type 2 diabetes mellitus.
Why this test is performed?
Your doctor may ask you to perform this test if you are suffering from symptoms such as frequent urination, hunger, blurred vision, fatigue, increased thirst or dry mouth, unexplained weight loss or weight gain, poor wound healing, foot pain and numbness, frequent infections, itching around penis or vagina, sweating, fast heart rate, sleepiness, headache, nausea, vomiting, etc. which are common symptoms of diabetes mellitus. In some cases, such as the removal of an insulinoma (a tumor of the pancreas), your doctor may ask you to perform this test to determine the effectiveness of the treatment. This test may be performed either alone or in a combination with other tests for better diagnosis.
This test is also done to understand whether an individual is having pancreatitis (inflammation of the pancreas), Cushing syndrome (pink and purple stretch marks along with round face and large tummy), acromegaly (enlargement of the face, hand, and feet), insulinomas (excess production of insulin due to tumor in the pancreas). If the patient exhibits symptoms of diabetes, the doctor may ask the patient to undergo insulin fasting test to determine the status of insulin secretion.
Medications such as corticosteroids, levodopa, oral contraceptives, etc. may alter the results of this test. Hence, it is advised that you report all your current medications to your healthcare practitioner before undergoing this test.
The frequency of this test depends on various factors like suspected diabetes mellitus, personal history of diabetes, family history of diabetes, body weight, history of heart disease, high blood pressure, gestational diabetes (high blood sugar levels during pregnancy), imbalance of female sex hormones, polycystic ovary disease, etc.
Inform your doctor if you are on any medications, have any allergies or underlying medical conditions before your Insulin Fasting. Your doctor will give specific instructions depending on your condition on how to prepare for Insulin Fasting.
Fasting Insulin test is done after you have fasted (without eating or drinking anything) for a whole night or for 8 to 12 hours. Usually, the blood is drawn in the morning after an overnight fast.
If the test result falls within the normal reference range, then the insulin production is normal and you may not need further medical intervention.
Increased levels of insulin may be due to obesity, insulinoma, type-2 diabetes mellitus, infantile hypoglycemia, hyperinsulinism (increase in the insulin levels than the normal range), Cushing’s syndrome (pink and purple stretch marks along with round face and large tummy), acromegaly (enlargement of the face, hand, and feet), hyperthyroidism (excess production of hormones from thyroid gland), insulin resistance, etc.
Decreased levels of insulin may indicate hypopituitarism (decrease in hormone production by the pituitary gland), Type-1 diabetes mellitus, cystic fibrosis, pancreatitis (inflammation in the pancreas), pancreatic cancer, etc.
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