What Are the Causes of Elevated Insulin Levels?

Do you have a high insulin level? Doctors order fasting insulin levels if they're looking for insulin resistance or if they're concerned that a person has an insulin-producing tumor called an insulinoma. What are the causes of a high insulin level in the blood?

The Most Common Cause of Elevated Insulin Levels: Insulin Resistance

Insulin resistance is a common condition where cells don't respond as readily to insulin the pancreas produces. As a result, the pancreas has to pump out more to successfully get glucose into cells. Insulin resistance is a precursor to type 2 diabetes and heart disease, which is why it's important to make the diagnosis early. Losing weight, dietary changes and exercise helps to correct this condition and prevent type 2 diabetes.

Obesity

You can have a high insulin level if you're obese. Fat cells produce fatty acids and proteins called cytokines that make cells more resistant to insulin. This leads to a high fasting insulin level for the same reason insulin resistance does.

Medications

Some medications including oral contraceptives, corticosteroids and levodopa used to treat Parkinson's disease causes elevated insulin levels in some cases. For this reason, it's important to let your doctor know about any medications you're taking.

Diseases Associated With a High Insulin Level

Small tumors of the islet cells of the pancreas cause increased insulin production. When these tumors overproduce insulin it enters the bloodstream and can be detected through a fasting insulin blood test. Fortunately, 9 out of 10 of these tumors are benign, but they still require treatment.

A condition called acromegaly may cause insulin levels to rise. Acromegaly is a condition where the body produces too much growth hormone. It's usually caused by a small tumor on the pituitary gland in the brain - and it can be associated with abnormal growth of the hands and feet and enlargement of facial features.

Cushing's syndrome is a condition where the body makes too much cortisol often due to a small tumor in the pituitary gland. A person with Cushing's will gain weight, especially in the waist and abdomen, and have an elevated blood pressure. They also may have muscle weakness, fatigue, a moon-shaped face and skin changes along with elevated insulin levels.

Elevated Insulin Levels: The Bottom Line?

In most cases, a high fasting insulin level is a sign of insulin resistance, but in some cases, it can be caused by more serious conditions such as Cushing's syndrome or

acromegaly. That's why a physical exam is important to rule out these conditions as the cause of elevated insulin levels.

References:

Lab Test Online. "Insulin: The Test"

Merck Manual. Eighteenth edition. 2006.

J Clin Invest. 1967 October; 46 (10) : 1549-1557.