Insulin and glucagon are hormones that help regulate the levels of blood glucose, or sugar, in your body. Glucose, which comes from the food you eat, moves through your bloodstream to help fuel your body.

Insulin and glucagon work together to balance your blood sugar levels, keeping them in the narrow range that your body requires. These hormones are like the yin and yang of blood glucose maintenance. Read on to learn more about how they function and what can happen when they don’t work well.

Insulin and glucagon work in what’s called a negative feedback loop. During this process, one event triggers another, which triggers another, and so on, to keep your blood sugar levels balanced.

How insulin works

During digestion, foods that contain carbohydrates are converted into glucose. Most of this glucose is sent into your bloodstream, causing a rise in blood glucose levels. This increase in blood glucose signals your pancreas to produce insulin.

The insulin tells cells throughout your body to take in glucose from your bloodstream. As the glucose moves into your cells, your blood glucose levels go down. Some cells use the glucose as energy. Other cells, such as in your liver and muscles, store any excess glucose as a substance called glycogen. Your body uses glycogen for fuel between meals.

Read more: Simple vs. complex carbs »

How glucagon works

Glucagon works to counterbalance the actions of insulin.

About four to six hours after you eat, the glucose levels in your blood decrease, triggering your pancreas to produce glucagon. This hormone signals your liver and muscle cells to change the stored glycogen back into glucose. These cells then release the glucose into your bloodstream so your other cells can use it for energy.

This whole feedback loop with insulin and glucagon is constantly in motion. It keeps your blood sugar levels from dipping too low, ensuring that your body has a steady supply of energy.

glucosesugar that travels through your blood to fuel your cells
insulina hormone that tells your cells either to take glucose from your blood for energy or to store it for later use
glycogena substance made from glucose that’s stored in your liver and muscle cells to be used later for energy
glucagona hormone that tells cells in your liver and muscles to convert glycogen into glucose and release it into your blood so your cells can use it for energy
pancreasan organ in your abdomen that makes and releases insulin and glucagon

Your body’s regulation of blood glucose is an amazing metabolic feat. However, for some people, the process doesn’t work properly. Diabetes mellitus is the best known condition that causes problems with blood sugar balance.

Diabetes refers to a group of diseases. If you have diabetes or prediabetes, your body’s use or production of insulin and glucagon are off. And when the system is thrown out of balance, it can lead to dangerous levels of glucose in your blood.

Type 1 diabetes

Of the two main types of diabetes, type 1 diabetes is the less common form. It’s thought to be an autoimmune disorder in which your immune system destroys the cells that make insulin in your pancreas. If you have type 1 diabetes, your pancreas doesn’t produce insulin. As a result, you must take insulin every day. If you don’t, you’ll get very sick or you could die. For more information, read about the complications of type 1 diabetes.

Learn more: Everything you need to know about insulin »

Type 2 diabetes

With type 2 diabetes, your body makes insulin but your cells don’t respond to it normally. They don’t take in glucose from your bloodstream as well as they once did, which leads to higher blood sugar levels. Over time, type 2 diabetes makes your body produce less insulin, which further raises your blood sugar levels.

Gestational diabetes

Some women develop gestational diabetes late in their pregnancies. In gestational diabetes, pregnancy-related hormones may interfere with how insulin works. This condition normally disappears after the pregnancy ends. However, if you’ve had gestational diabetes, you’re at greater risk of developing type 2 diabetes in the future.


If you have prediabetes, your body makes insulin but doesn’t use it properly. As a result, your blood glucose levels are raised, though not as high as they would be if you had type 2 diabetes. Many people who have prediabetes go on to develop type 2 diabetes.

Knowing how your body works can help you stay healthy. Insulin and glucagon are two critical hormones your body makes to keep your blood sugar levels balanced. It’s helpful to understand how these hormones function so you can work to avoid diabetes.

If you have more questions about insulin, glucagon, and blood glucose, talk to your doctor. Questions you have might include:

  • Is my blood glucose at a safe level?
  • Do I have prediabetes?
  • What can I do to avoid developing diabetes?
  • How do I know if I need to take insulin?