Insulin is a hormone (a chemical substance that acts as a messenger in the human body) that is secreted by an abdominal organ called the pancreas. It controls the breakdown of carbohydrates, fats and proteins in the body. It also guides the liver and muscles to store glucose and fat that can be used during periods of increased energy requirements and fasting. Insulin is a “key” that unlocks the cell gates so that glucose from the blood enters the cells. The cells of the muscle and fat tissue are dependent solely on insulin for glucose uptake and use.
The lack of insulin in the body or inefficient insulin action at cellular levels causes blood sugar levels to spike (hyperglycemia). Hyperglycemia is the hallmark of diabetes mellitus. Insulin is the only hormone in the body that can prevent hyperglycemia.
Hyperinsulinemia: Some individuals require higher than normal amounts of insulin to maintain their blood sugar levels. This condition is called hyperinsulinemia. It is often found to co-exist with insulin resistance.
Insulin resistance is a state in which a given insulin concentration does not cause an expected dip in blood sugar levels. Insulin resistance may be caused by
- Antibodies to insulin or to the site in the cell where insulin binds (seen in autoimmune diseases such as systemic lupus erythematosus and Hashimoto’s thyroiditis).
- Suboptimal quality insulin (less effective insulin) as seen in people with certain genetic diseases.
- Genetic tendency to insulin resistance as seen in the people of Latino, African American, Native American or Asian-American heritage.
Certain conditions may cause temporary insulin resistance and resultant hyperinsulinemia, but as soon as the underlying cause is corrected, insulin resistance goes away. These conditions include long-term stress, infections, long-term sleep deprivation, obesity and pregnancy. These conditions release the stress hormones in the body. Stress hormones are a known cause of insulin resistance and high insulin levels.
The other causes of high insulin levels that may need medical intervention are as follows.
Metabolic syndrome is a cluster of multiple maladies including
|Tumors of insulin-secreting cells||
High insulin levels often have no clinical symptoms and may go undetected. Rarely, they may cause recurrent low blood sugar, which may be seen as palpitations, irritability, sweating and hunger pangs. Some individuals with long-standing insulin resistance may develop skin tags over the neck and armpits. Others may have dark underarms and groins (acanthosis nigricans).
What are normal insulin levels?
Insulin levels in the blood can be interpreted using a simple blood test that is performed after eight hours of fasting. This test must be performed in individuals with suspected insulin resistance or as a part of a hormonal panel in metabolic syndrome evaluation.
The normal values of insulin are as follows.
|Insulin level||Insulin level (SI units*)||Values in pmol/L|
|Fasting||<25 mIU/L||<174 pmol/L|
|30 minutes after glucose administration||30-230 mIU/L||208-1,597 pmol/L|
|1 hour after glucose administration||18-276 mIU/L||125-1,917 pmol/L|
|2 hours after glucose administration||16-166 mIU/L||111-1,153 pmol/L|
|≥3 hours after glucose administration||<25 mIU/L||<174 pmol/L|
What are the consequences of high insulin levels?
The following are the consequences of high insulin levels:
- High insulin levels generally translate into an overworked pancreas. This may be followed by the exhaustion of the pancreatic cells, resulting in the development of diabetes mellitus.
- Diabetes further brings on complications such as heart disease, nerve damage, eye damage and kidney damage.
- High insulin levels have been linked to the development of certain cancers such as cancer of the gut, although it is not proven conclusively.
- Non-alcoholic fatty liver disease (NAFLD) is a dysfunction of the liver due to increased fat deposition inside the organ. It is seen in individuals with insulin resistance.
- High insulin levels hasten plaque buildup in the large blood vessels causing atherosclerosis (blockages).
- High levels of insulin affect the estrogen-progesterone ratio in the ovaries and may result in polycystic ovarian syndrome (PCOS) that may cause irregular periods and infertility in young women.
Health Solutions From Our Sponsors
The Clinical Biochemist Reviews