Insulin Fasting, Serum

Insulin testing has several possible uses. Insulin is a hormone that is produced and stored in the beta cells of the pancreas. Insulin helps transport glucose , the body's main source of energy, from the blood to within cells. If a person makes too little insulin or is resistant to its effects, cells starve. If someone makes too much, as may happen with an insulin-producing tumor (insulinoma) for example, then symptoms of low blood glucose (hypoglycemia) emerge. Insulin testing may be used to help: Diagnose an insulinoma, verify that removal of the tumor has been successful, and/or to monitor for recurrence Diagnose the cause of hypoglycemia in an individual with signs and symptoms Identify insulin resistance Monitor the amount of insulin produced by the beta cells in the pancreas (endogenous); in this case, a C-peptide test may also be done. Insulin and C-peptide are produced by the body at the same rate as part of the conversion of proinsulin to insulin in the pancreas. Both tests may be ordered when a health practitioner wants to evaluate how much insulin in the blood is made by the body and how much is from outside (exogenous) sources such as insulin injections. The test for insulin measures insulin from both sources while the C-peptide test reflects insulin produced by the pancreas. Determine when a type 2 diabetic might need to start taking insulin to supplement oral medications Determine and monitor the success of an islet cell transplant intended to restore the ability to make insulin, by measuring the insulin-producing capacity of the transplant Insulin testing may be ordered with glucose and C-peptide tests. Insulin levels are also sometimes used in conjunction with the glucose tolerance test (GTT). In this situation, blood glucose and insulin levels are measured at pre-established time intervals to evaluate insulin resistance. When is it ordered?
Insulin levels are most frequently ordered following a low glucose and/or when someone has acute or chronic symptoms of low blood glucose (hypoglycemia) caused by, for example, an insulinoma. Symptoms of hypoglycemia may include: Sweating Palpitations Hunger Confusion Blurred vision Dizziness Fainting In serious cases, seizures and loss of consciousness These symptoms may indicate low blood glucose but may also be seen with other conditions. An insulin test may also be done when an individual has or is suspected of having insulin resistance. This may include people with type 2 diabetes, polycystic ovarian syndrome (PCOS), prediabetes or heart disease, or metabolic syndrome. A health practitioner also may order insulin and C-peptide tests after an insulinoma has been successfully removed to verify the effectiveness of treatment and then order the tests periodically to monitor for recurrence. Periodic testing may also be used to monitor the success of an islet cell transplant by measuring the insulin-producing capacity of the transplant.

Can I do an insulin test at home?

No. Although glucose levels can be monitored at home, insulin tests require specialized instruments and training are are perforemd at laboratories.

Why does insulin have to be injected?

Insulin must be injected or given via an insulin pump. It ca ot be given orally because it is a protein and is broken down in the stomach before it can be absorbed.

How is an insulinoma treated?

Insulinomas are insulin-producing tumors that are usually benign. They are typically treated by being located and removed. Once removed, generally they do not return.

What else is important about insulin resistance?

insulin resistance is a warning signal that the body is having problems processing glucose and it is characteristic of prediabetes. People with early or moderate insulin resistance often don't have any symptoms, but if their condition is ignored, it puts them at a much greater risk of developing type 2 diabetes, hypertension, hyperlipidemia, and/or heart disease several years down the road. Abdominal obesity, insulin resistance, dyslipidemia, and hypertension form a set of risk factors that are referred to as metabolic syndrome.

Risk factors for insulin resistance include:

Obesity, especially abdominal obesity Family history of Diabetes or insulin resistance Gestational diabetes Polycystic ovary syndrome

Treatment of insulin resistance involves changes in diet and lifestyle. The American Diabetes Association recommends losing excess weight, getting regular amounts of moderate intensity physical activity, and increasing dietary fiber to lower blood insulin levels and increase the body's sensitivity to it.