Insulin is a hormone made in the pancreas, an organ located behind the stomach. The pancreas contains clusters of cells called islets. Beta cells within the islets make insulin and release it into the blood.

Insulin plays a major role in metabolism—the way the body uses digested food for energy. The digestive tract breaks down carbohydrates—sugars and starches found in many foods—into glucose. Glucose is a form of sugar that enters the bloodstream. With the help of insulin, cells throughout the body absorb glucose and use it for energy.

Insulin’s Role in Blood Glucose Control

When blood glucose levels rise after a meal, the pancreas releases insulin into the blood. Insulin and glucose then travel in the blood to cells throughout the body.

• Insulin helps muscle, fat, and liver cells absorb glucose from the bloodstream, lowering blood glucose levels.
• Insulin stimulates the liver and muscle tissue to store excess glucose. The stored form of glucose is called glycogen.
• Insulin also lowers blood glucose levels by reducing glucose production in the liver.

In a healthy person, these functions allow blood glucose and insulin levels to remain in the normal range.

Types of Insulin

There are many different types of insulin. The type lets you know how fast the insulin starts working or how long it lasts in your body. Your health care provider will help you find the insulin that is best for you.

• Rapid-Acting – This insulin starts working within 15 minutes after you use it. It is mostly gone out of your body after a few hours. It should be taken just before or just after you eat.
• Short-Acting – This insulin starts working within 30 minutes to 1 hour after you use it. It is mostly gone out of your body after a few hours. It should be taken 30-45 minutes before you eat.
• Intermediate-Acting – This insulin starts working within 2-4 hours after you use it. It reaches its highest level in your blood around 6-8 hours after you use it. It is often used to help control your blood sugar between meals. Some people use this type of insulin in the morning, at bedtime, or both.
• Long-Acting – This insulin starts working within 2 to 4 hours after you use it. It can last in the body for up to 24 hours. It is often used in the morning or at bedtime to help control your blood sugar throughout the day.
• Pre-Mixed – This is a mix of two different types of insulin. It includes one type that helps to control your blood sugar at meals and another type that helps between meals.

General Tips

• Never share insulin needles (syringes) or devices.
• Ask your doctor or nurse to show you how to inject your insulin.
• Always wash your hands before you inject your insulin.
• Do not inject your insulin in the exact same spot on your body each time.
  • The skin may get thick or thin if you use the same spot.
  • Inject in the same general area of your body.
• Do not use your insulin if it looks cloudy or looks like something is floating in it. Take it back to the drug store for a new one.
• Do not use insulin needles (syringes), pens, and injectors after the expiration date printed on the label or on the box.