What Is Insulin?

The insulin your body makes naturally is a hormone. Insulin helps move sugar from the blood into the body’s cells, where it can be used for energy.

The pancreas releases insulin all the time. The pancreas is an organ that sits near the stomach. Special cells in the pancreas, called beta cells, make insulin. In between meals, the pancreas releases a low level of insulin to help the body produce energy.

When you eat, your blood sugar (also known as blood glucose) rises. The pancreas releases more insulin to take sugar from the food you eat and bring it to the cells to be changed into energy. This brings the blood sugar level in the blood back down.

Insulin works like a key, unlocking cells to help deliver sugar from the blood. Every cell in the body has a lock on its cell wall, called a receptor. Insulin fits into that lock like a key, allowing sugar to enter the cells.

When the body is not able to make enough insulin, blood sugar is locked out of the cells, causing it to stay in the bloodstream. This leads to blood sugar building until the levels are too high, which is also called hyperglycemia. This extra sugar is what makes people feel the symptoms of diabetes, such as often feeling tired or thirsty.

In the case of diabetes, when the body is either not making enough insulin, or cannot use it properly, insulin therapy is often used to replace what the body no longer produces.


History of Insulin Therapy

  • From the 1920s to the 1980s, insulin from animals is used for treatment
  • In the 1980s, the first generation of man-made insulin, called "human insulin," is created. This man-made insulin was genetically identical to the body’s naturally produced insulin
  • By the late 1990s, man-made insulin analogs were being developed. Insulin analogs are similar to regular human insulin, but they are changed slightly to allow them to act more quickly or slowly than regular human insulin

Different types of insulin analogs are available. Every one has a specific:

Onset of action (when they start to work)

Time of peak action (when their effect on blood sugar is greatest)

Duration of action (how long they work)

Long-acting insulin (also known as basal). This type works more slowly. It works longer to control blood sugar between meals and when you sleep. Long-acting insulin is taken either once or twice a day at the same time every day, often with your evening meal or at bedtime to help give up to 24-hour insulin coverage. This is often the first insulin prescribed by your doctor for type 2 diabetes.

Fast-acting insulin (also known as bolus or rapid-acting). This type is taken shortly before mealtime. It works quickly to control the rapid rise in blood sugar after meals. Fast-acting insulin closely mimics the body's natural release of insulin at mealtime.

Premix insulin. For appropriate people with diabetes, premix insulin combines the action of a fast-acting and long-acting insulin.

These types of insulin help manage diabetes. But no one type is right for everyone. Each person's insulin need is different. And each person's insulin need may change over time.

Insulin analogs are preferred by the American Association of Clinical Endocrinologists or AACE. Your doctor and diabetes care team will prescribe the insulin that is best for you.

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