Insulin is an essential hormone. It helps your body turn food into energy and manages your blood sugar levels. If you have diabetes, your body can’t make enough insulin or can’t use it properly. Your healthcare provider can prescribe manufactured insulin that you take through an injection (shot), injectable pen or pump. Inhalable insulin is also an option.
Insulin is a naturally occurring hormone your pancreas makes that’s essential for allowing your body to use sugar (glucose) for energy. If your pancreas doesn’t make enough insulin or your body doesn’t use insulin properly, it leads to high blood sugar levels (hyperglycemia). This results in diabetes.
There are also manufactured types of insulin that people with diabetes use to manage the condition.
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Insulin moves glucose from your blood into cells all over your body. Glucose comes from both the food and drinks you consume and your body’s natural release of stored glucose (glycogen). Glucose is your body’s main — and preferred — source of energy.
All of your body’s cells need energy. Think of insulin as the key that opens the doors of the cells in your body. Once insulin opens your cell doors, glucose can leave your bloodstream and move into your cells where you use it for energy.
Without enough insulin, glucose can’t get into your cells and instead builds up in your blood. This leads to high blood sugar and diabetes. A total lack of insulin for a prolonged time leads to a life-threatening complication called diabetes-related ketoacidosis (DKA).
Insulin lowers your blood sugar level. Glucagon (another hormone) naturally raises it. Your body uses these two hormones to balance out your blood sugar level to keep it in a healthy range.
If you have diabetes, too much (manufactured) insulin can lead to low blood sugar (hypoglycemia). In this case, you may need to consume sugar to raise your blood sugar level. There are manufactured forms of glucagon available with a prescription for emergency use to treat severe low blood sugar. Talk to your healthcare provider or diabetes care and education specialist to find out if glucagon should be included in your treatment plan.
Your pancreas produces insulin. More specifically, beta cells in the islets of Langerhans in the pancreas make the hormone. This is the endocrine function of your pancreas, meaning it releases insulin directly into your bloodstream.
Many conditions can develop when you have a lack of natural insulin or too much.
Diabetes results from a lack of functional insulin, which leads to high blood sugar.
Damage to your pancreas causes certain types of diabetes, like:
Insulin resistance is the other major cause of diabetes. This happens when cells in your muscles, fat and liver don’t respond as they should to insulin. Insulin resistance can lead to conditions like:
There’s also a genetic form of diabetes called maturity-onset diabetes of the young (MODY). MODY, also called monogenic diabetes, happens due to an inherited genetic mutation (change) that affects how your body makes and uses insulin.
A rare tumor called an insulinoma makes your pancreas produce excess insulin. This causes you to have frequent — and sometimes severe — low blood sugar. Most insulinomas are curable with surgery.
There are many different types of insulin. Most types are injectable, either through a needle, pen or pump. There’s also inhalable insulin. If you have diabetes, your provider will work with you to prescribe the right type(s) for you and adjust the dosage when your needs change.
The main types of insulin based on how fast they work and how long they last include:
The most common complication of insulin treatment is low blood glucose levels (hypoglycemia) from taking too much insulin for your needs.
Other possible side effects of insulin treatment, which are rare, include:
You can inject several areas of your body with insulin. In general, the areas where you typically have body fat (adipose tissue) are the best sites. These include:
It’s important to mix up where you inject insulin to prevent skin complications.
“Normal” doesn’t really exist for insulin levels because each person is different, and your insulin needs vary widely from hour to hour every day. Several factors impact your insulin levels, like:
In addition, there’s no common test to check your insulin levels specifically.
Some people — but not all — with Type 2 diabetes need insulin to best manage the condition.
There are several other types of medications for Type 2 diabetes, like oral medications and GLP-1 agonist injections. These medications combat insulin resistance in different ways. If insulin resistance is severe, these medications may not be enough to maintain healthy blood sugar levels. This is when you’d need insulin.
A person with insulin-dependent diabetes needs manufactured insulin to live. Without it, DKA, a life-threatening complication, can develop.
DKA is an acute complication, which means it has a severe and sudden onset. It can develop within 24 hours. If you’re vomiting, it could develop much more quickly. It’s essential to call your healthcare provider or go to the hospital as soon as you experience symptoms to get treatment before DKA becomes more severe. Without treatment, DKA is fatal.
A note from Cleveland Clinic
Insulin is an essential hormone that helps you stay healthy and keeps your body working like it should. If your body can’t make enough insulin or use it properly, your healthcare provider can prescribe manufactured insulin as a diabetes treatment. Follow your provider’s instructions carefully when giving yourself insulin. And be sure to seek medical help right away if you have signs of DKA or experience severe low blood sugar.
Last reviewed by a Cleveland Clinic medical professional on 01/17/2024.
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