Diabetes and insulin

Insulin is a naturally occurring hormone made by your pancreas that regulates the amount of sugar (glucose) in your blood. Insulin helps glucose enter your cells so it can be used for energy and helps keep your blood sugar level from getting too high (hyperglycemia). Read on to learn about the connection between diabetes and insulin.

Having high blood sugar for a long period can permanently damage parts of your body. It can cause serious health problems, such as heart disease, blindness, nerve damage and kidney damage.

Type 1 diabetes happens when your body does not make insulin. Type 1 diabetes was once commonly known as insulin-dependent diabetes.

Prediabetes and type 2 diabetes happens when your body does not use insulin effectively or doesn't make enough insulin.

In type 1 diabetes, the body does not make any insulin, a hormone that allows the body to use sugar from food to supply energy to the cells in the body. An individual with type 1 diabetes must take insulin injections or use an insulin pump to live. Type 1 diabetes is more common in children, but it can occur at any time.  

In type 2 diabetes, the body can still produce insulin, it just doesn’t use it like it should, so the individual needs to supplements with additional insulin or other anti-diabetic medications. Although more common in older individuals, a growing number of children and adolescents are being diagnosed with type 2 diabetes.

There are different types of insulin. The choice depends on how quickly they work, when they peak and how long they last. Your healthcare provider will help you find the right type of insulin for your health needs and your lifestyle. You may also be prescribed more than one type of insulin.

The many types of insulin vary based on the following characteristics:

• How long the insulin takes to begin lowering blood sugar (onset)
• When the insulin reaches its maximum effect in terms of lowering blood sugar (peak)
• How long the insulin continues to lower blood glucose (duration)

There are seven different types of insulin available:

• Rapid-acting: starts to work within a few minutes and lasts for a couple of hours. It is usually taken right before a meal and is often used with a longer acting insulin.
• Inhaled: begins working within 12 to 15 minutes, peaks by 30 minutes, and is out of your system in 180 minutes. It is not a substitute for long-acting insulin and must be used as directed by your healthcare provider. It’s usually taken before a meal.
• Regular or short-acting: usually reaches the bloodstream within 30 minutes after injection. It peaks anywhere from 2 to 3 hours after injection, and lasts for about 3 to 6 hours. This insulin is usually taken 30-60 minutes before a meal
• Intermediate-acting: generally reaches the bloodstream about 2 to 4 hours after injection, peaks 4 to 12 hours later, and can last for up to 18 hours. This allows for a longer span of coverage and is often used with rapid or short acting insulin.
• Long-acting: reaches the bloodstream several hours after injection and can work up to an entire day. The user can supplement with rapid or short acting insulin if needed
• Ultra long-acting: reaches the bloodstream in 6 hours, does not peak and lasts about 36 hours or longer.
• Premixed : reaches the bloodstream in 5 minutes to 1 hour. The peak varies based on the combination of intermediate and short acting insulin and lasts for between 10 to 16 hours.  This is usually taken 10 to 30 minutes before breakfast and dinner. 

An insulin pump is a small, computerized device that delivers insulin through a thin tube placed under your skin. You can place the thin tube in an area on your body with fatty tissue such as your belly, buttock, thigh or upper arm. Insulin pumps deliver insulin doses in two ways:

• As a steady, measured and continuous dose of insulin
• As a burst of insulin close to mealtime to control the rise in blood sugar after a meal

There are different kinds of insulin pumps available. You can talk to your healthcare provider to decide if an insulin pump is the right choice for you. But remember, even with an insulin pump, it is important for you to continue to check your blood sugar levels on a regular basis.

Andy Stergachis is professor of pharmacy & global health, University of Washington.

Clinically reviewed and updated by Rebeca Thomas, RN, BSN, CPHQ, March 2022.