Insulin and glucagon help maintain blood sugar levels. Glucagon helps prevent blood sugar from dropping, while insulin stops it from rising too high.

Insulin and glucagon work together in a balance and play a vital role in regulating a person’s blood sugar levels. Glucagon breaks down glycogen to glucose in the liver. Insulin enables blood glucose to enter cells, where they use it to produce energy.

Together, insulin and glucagon help maintain homeostasis, where conditions inside the body hold steady. When a person’s blood sugar is too high, their pancreas secretes more insulin. When their blood sugar levels drop, their pancreas releases glucagon to raise them.

This balance helps provide sufficient energy to the cells while preventing damage that can result from consistently high blood sugar levels.

If a person’s body cannot maintain this balance, diabetes and other conditions can result. Prescription insulin and glucagon can help keep a person’s blood sugar levels within safe limits.

In this article, we explain the functions and processes of insulin and glucagon, how they work as medications, and their effects on a person’s blood sugar levels.

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When a person consumes carbohydrates through foods, their body converts them into glucose, a simple sugar that serves as a vital energy source.

However, the body does not use all of this glucose at once. Instead, it converts some into storage molecules called glycogen and stores them in the liver and muscles.

When the body needs energy, glucagon in the liver converts glycogen back into glucose. From the liver, it enters the bloodstream. There, insulin enables it to enter cells and provide energy for all of the body’s functions

In the pancreas, different types of islet cells release insulin and glucagon. Beta cells release insulin while alpha cells release glucagon.

How insulin works

The body’s cells need glucose for energy, and insulin enables glucose to enter the cells.

Insulin attaches to insulin receptors on cells throughout the body, instructing them to open and grant entry to glucose.

Low levels of insulin constantly circulate throughout the body. A spike in insulin signals the liver that a person’s blood glucose level is also high, causing the liver to absorb glucose and change it into glycogen.

When blood sugar levels drop, glucagon instructs the liver to convert the glycogen back to glucose, causing a person’s blood sugar levels to return to normal.

How glucagon works

The liver stores glucose to power cells during periods of low blood sugar. Skipping meals and getting inadequate nutrition can lower a person’s blood sugar levels. By storing glucose, the liver ensures the body’s blood glucose levels remain steady between meals and during sleep.

When a person’s blood glucose levels fall, pancreatic cells secrete glucagon, stimulating two processes: gluconeogenesis and glycogenolysis. The liver provides or stimulates the production of glucose using these processes.

In glycogenolysis, glucagon instructs the liver to convert glycogen to glucose, making glucose more available in the bloodstream.

In gluconeogenesis, the liver produces glucose from the byproducts of other processes. Gluconeogenesis also occurs in the kidneys and some other organs.

When the body’s glucose levels rise, insulin enables the glucose to move into cells.

Insulin and glucagon work in a cycle. Glucagon interacts with the liver to increase blood sugar, while insulin reduces blood sugar by helping the cells use glucose.

Blood sugar levels

A person’s blood sugar levels vary throughout the day, but insulin and glucagon keep them within a healthy range overall.

When the body does not absorb or convert enough glucose, blood sugar levels remain high. Insulin reduces the body’s blood sugar levels and provides cells with glucose for energy by helping cells absorb glucose.

When blood sugar levels are too low, the pancreas releases glucagon. Glucagon instructs the liver to release stored glucose, which causes the body’s blood sugar levels to rise.

Hyperglycemia refers to high blood sugar levels. Persistently high levels can cause long-term damage throughout the body.

Hypoglycemia means blood sugar levels are low. Its symptoms include faintness and dizziness, and it can be life threatening.

People with type 1 diabetes need to take insulin regularly, but glucagon is usually only for emergencies.


The dose and method of delivery will depend on an individual’s needs, and they will work with a doctor to adjust the dose as necessary. People can take insulin in various ways, such as pre-loaded syringes, pens, or pumps.

Adverse effects can occur if a person takes too much or too little insulin or uses it with certain other drugs. For this reason, they will need to follow their treatment plan with care.

What are the side effects of insulin therapy?


Glucagon — available under the brand name GlucaGen — is usually for emergency use only, such as when a person’s blood sugar levels fall below 70 milligrams per deciliter (mg/dl).

Ways of giving glucagon include injections or a nasal spray. It also comes as a kit, with a syringe, some glucagon powder, and a liquid to mix with it. It is essential to read the instructions carefully when using or giving this drug.

Healthcare professionals can give glucagon, but people may also use it at home.

After giving glucagon, someone should monitor the person for adverse effects. The most common adverse effect is nausea, but they may also vomit. In some cases, an allergic reaction may occur.

Blood sugar levels should return to safer levels within 10–15 minutes. After this, the person should ingest some candy, fruit juice, crackers, or other high-energy food.

Doctors may also use glucagon when diagnosing problems with the digestive system.

A range of factors, including insulin resistance, diabetes, and an unbalanced diet, can cause blood sugar levels to spike or plummet.

The standard measurement units for blood sugar levels are milligrams per deciliter (mg/dl). Ideal blood sugar ranges are as follows:

TimingBlood glucose level (mg/dl)
Before a meal
2 hours after the start of a mealLess than 180

Read more about optimal blood sugar levels here.

High blood sugar can be a sign of diabetes, but it can also occur with other conditions. Without intervention, high blood sugar can lead to severe health problems. In some cases, it can become life threatening. Insulin and glucagon help manage blood sugar levels.

High blood sugar

In addition to diabetes, possible causes of high blood sugar include:

People with high blood sugar may not notice symptoms until complications appear.

If symptoms occur, they include:

  • urinating more often than usual
  • excessive thirst
  • weight loss

Over time, high blood sugar may lead to:

  • increased hunger
  • slow wound healing
  • itchy, dry skin
  • more frequent infections
  • headaches
  • fatigue or difficulty concentrating
  • blurred vision

Low blood sugar

Hypoglycemia is most likely to affect people with diabetes if they take their diabetes medication — such as insulin or glipizide — without eating.

But, it can happen for other reasons, for example:

  • malnutrition or starvation
  • liver disease
  • sepsis
  • a high alcohol consumption
  • the use of some medications

The symptoms of low blood sugar include:

Without treatment, low blood sugar can lead to seizures or loss of consciousness.

What are the different types of diabetes?

Insulin and glucagon are vital for maintaining moderate blood sugar levels.

Insulin helps the cells absorb glucose from the blood, while glucagon triggers a release of glucose from the liver.

People with type 1 diabetes need to take supplemental insulin to prevent their blood sugar levels from becoming too high.

In some cases, a doctor will recommend insulin for people with type 2 diabetes. However, diet and exercise are usually the first recommendations for this type.

If a person’s blood sugar levels fall too low, they may need glucagon. Very low blood sugar can become life threatening without medical intervention.