Glucagon - A Vital Hormone for Controlling Blood Sugar

The pancreas is nestled into the curve formed by the duodenum, which Is the first part of the small intestine. It makes both glucagon and insulin.
The pancreas is nestled into the curve formed by the duodenum, which Is the first part of the small intestine. It makes both glucagon and insulin. | Source

What is Glucagon?

Many people have heard of insulin, a hormone made by the pancreas that lowers the blood sugar level and that people with type 1 diabetes lack. There is another pancreatic hormone that also has an important effect on blood sugar, however. This hormone is glucagon. Glucagon has the opposite effect to insulin - it raises the blood sugar level instead of lowering it.

Glucose (blood sugar) is obtained from the food that we digest. The glucose enters our blood through the lining of the small intestine and is used as an energy source by our cells. The concentration of glucose in the blood is affected by the frequency of eating, the amount and types of food that we eat, the amount of exercise that we perform, the use of certain medications and other factors. Insulin and glucagon work to keep the glucose level in the blood constant, which is very important for the functioning of the brain.

The brain requires a continuous supply of glucose. A glucose level that is too low or too high can both be dangerous in the body. However, a very low blood sugar level will have an immediate effect on the brain, while the effects of continually high blood sugar take longer to develop.

The Pancreas and its Functions

Glucagon, The Pancreas and The Liver

Like insulin, glucagon is a peptide hormone and is made of amino acids. A glucagon molecule is a chain of twenty-nine amino acids. Glucagon and insulin are made in a part of the pancreas called the islets of Langerhans or the pancreatic islets. Glucagon is made by the alpha cells in the islets while insulin is made by the beta cells.

In the liver, glucose molecules are joined together to make a molecule called glycogen. Glycogen acts as a storage reservoir for glucose molecules. The liver absorbs glucose and makes glycogen when the glucose level in the blood is too high. It breaks glycogen down and releases glucose into the bloodstream when the blood glucose concentration is too low. The liver is also able to make glucose molecules from amino acids. Glucagon does its job by controlling specific activities in the liver.

Glucagon and glycogen are sometimes confused due to the similarities in their names. Glucagon is a peptide hormone made by the pancreas. Glycogen is a carbohydrate made by the liver.

The pancreas is an unusual organ. It has two completely different functions. The islet cells secrete hormones while the acinar cells secrete digestive enzymes.
The pancreas is an unusual organ. It has two completely different functions. The islet cells secrete hormones while the acinar cells secrete digestive enzymes. | Source

Effects of Glucagon on the Liver

As the blood glucose concentration rises and falls during our body's activities, insulin and glucagon act to keep the glucose level constant. When the blood sugar level is too low, glucagon stimulates the liver to produce glucose by two different methods.

Like all hormones, glucagon is a messenger that travels from its site of origin to its target organ through the blood. When glucagon reaches the liver it binds to receptors on the surface of the liver cells. Receptors are proteins on the cell membrane that cause a specific effect in the cell when they join to the correct molecule.

When glucagon joins to its receptors on liver cell membranes, enzymes that break down glycogen are activated. As the glycogen breaks down, glucose molecules are released. The glucose molecules are then transported into the blood, raising the blood sugar level. The breakdown of glycogen is called glycogenolysis.

Glucagon has another important effect on the liver which also raises the blood sugar level. It stimulates the conversion of amino acids to glucose, a process known as gluconeogenesis.

Glucagon, Insulin and Blood Sugar Level

Hypoglycemia in Type 1 Diabetics

Hypoglycemia is an abnormally low level of blood sugar. The decrease is much larger than the moderate decrease that develops when we haven't eaten for a while or when we've exercised, which glucagon compensates for. In hypoglycemia, the blood sugar may be dangerously low, which can prevent the brain from working properly.

People with diabetes are in danger of developing hypoglycemia. The condition may occur if the person takes too much insulin, exercises harder than normal, hasn't eaten enough, has drunk too much alcohol or has taken certain medications which have the side effect of lowering blood sugar.

In hypoglycemia, the body may not be able to produce enough glucagon to compensate for the lowered glucose level or they may not be able to produce glucagon fast enough. First aid and/or medical treatment may be necessary.

Most diabetics have a glucose meter or another method of measuring their blood sugar level. This helps them to prevent a problem from developing when their glucose level falls or rises.

Symptoms of Hypoglycemia

Some common symptoms of hypoglycemia include the following. Anyone who suspects that they experience or have experienced hypoglycemia should visit a doctor for a diagnosis and treatment recommendations.

  • trembling
  • sweating
  • blurred vision
  • tiredness
  • confusion
  • pale skin
  • headache
  • rapid or pounding heartbeat
  • hunger
  • feeling faint

Someone suffering from hypoglycemia may also have altered behavior, including aggression. In severe cases there may be seizures or a coma.

Severe Diabetic Hypoglycemia

Treatment for Hypoglycemia in Type 1 Diabetes

Mild to moderate hypoglycemia in diabetics is usually treated by giving the person sweet substances to eat or drink, such as glucose tablets, sugar, honey or fruit juices. This treatment may be followed by giving the person more substantial food, such as milk, crackers or a peanut butter sandwich. The person's condition must be monitored after the treatment.

Severe hypoglycemia is life threatening and must be treated by a doctor. In severe hypoglycemia the person loses consciousness or is barely conscious. They are also unable to swallow. A common treatment for severe hypoglycemia is a glucagon injection. Some diabetics have their own glucagon injector, which they carry around with them. Schools may keep a glucagon injector on their premises. Even if a helper injects a severely hypoglycemia diabetic with glucagon and the injection appears to eliminate the person's symptoms, the patient must see a doctor.

Family and acquaintances of someone with diabetes should be familiar with the symptoms of hypoglycemia and its treatments. If they are expected to give a glucagon injection when necessary, they should know the correct technique for giving the injection. Glucagon is supplied as a powder and must be mixed with sterile water just before injection. If it's mixed too early it will become inactive. The water is provided in the injection kit.

The instructions for giving a glucagon injection in the video below are good, but the narrator makes one error in the information that she presents. She says that glucagon is released by the liver when it is actually released by the pancreas.

How To Use a Glucagon Injector

Hypoglycemia in People Without Type 1 Diabetes

In type 1 diabetes, the pancreas produces no or very little insulin. In people with type 2 diabetes, the pancreas does produce insulin. However, the body's cells are resistant to the hormone and no longer respond appropriately to its presence. In some patients with Type 2 diabetes, the pancreas makes an insufficient amount of insulin.

People with Type 2 diabetes may sometimes need a glucagon injection, although loss of consciousness is less common when these patients experience hypoglycemia than when people with type 1 diabetes experience the condition. Non-diabetics may also develop hypoglycemia, but this condition generally isn't treated with glucagon injections.

There are glucagon receptors in the intestine and other parts of the body as well as in the liver.
There are glucagon receptors in the intestine and other parts of the body as well as in the liver. | Source

Glucagon Research

As with other hormones, scientists are finding that glucagon may have more functions and more complex behaviour than they previously thought. There are glucagon receptors on cells in the brain, kidney, intestinal smooth muscle and adipose (fat) tissue as well as on liver cells.

The instructions for making glucagon are encoded in the GCG gene. Like other genes, the GCG gene contains instructions for making a protein. This protein is called preproglucagon. It's broken down into smaller proteins, one of which is glucagon. The functions of the other proteins that are produced is of great interest to researchers.

Another topic of interest for scientists is the control of glucagon production and secretion by the nervous system. At the moment, this control is not well understood. Understanding the control system could be very important for helping diabetics.

An islet of Langerhans or pancreatic islet (the paler area in this stained slide) makes both glucagon and insulin.
An islet of Langerhans or pancreatic islet (the paler area in this stained slide) makes both glucagon and insulin. | Source

Treating Diabetes

Type 1 diabetes was once thought to be simply a pancreatic problem in which insulin is no longer produced by the pancreatic islets. According to this theory, if the insulin is replaced, the person's symptoms will disappear.

A lack of insulin is certainly involved in diabetes and insulin is definitely an essential treatment for diabetes. However, researchers suspect that the interplay between the central nervous system, insulin, glucagon and perhaps hormones that resemble glucagon are also important in diabetes. Understanding these interactions may lead to new treatments for the disease.

The human endocrine system, or the hormonal system, is very complex. There's still a lot to be learned about hormone identity, secretion and action. Researchers are gradually discovering how hormones such as glucagon work, however, which could be very helpful for treating disease.

© 2012 Linda Crampton

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Comments 18 comments

billybuc profile image

billybuc 4 years ago from Olympia, WA

Really very informative and educational. I like the way you can write about something very technical and make it easy to understand. Well done my friend.


AliciaC profile image

AliciaC 4 years ago from British Columbia, Canada Author

Thank you for the visit and comment, Bill! I appreciate your comment very much, because my goal was to make the topic easy to understand for someone who doesn't have a science background.


GoodLady profile image

GoodLady 4 years ago from Rome, Italy

You did succeeded in making the topic understandable. I was fascinated throughout, very, very interesting.


AliciaC profile image

AliciaC 4 years ago from British Columbia, Canada Author

Thank you very much for the kind comment, GoodLady!! I appreciate your visit.


mperrottet profile image

mperrottet 4 years ago from Pennsauken, NJ

Very informative article. My husband is diabetic, so I'm always interested in things related to diabetes.


AliciaC profile image

AliciaC 4 years ago from British Columbia, Canada Author

Thanks, mperrottet. It's nice to meet you! I have a friend who is a diabetic, but no one in my family has the disorder.


editorsupremo profile image

editorsupremo 4 years ago from London, England

Excellent and informative hub. Insulin is the hormone that everybody knows is related to diabetes but very little is mentioned or known about glucagon. Thanks for reporting on this other hormone that can have a serious effect on blood glucose levels.


AliciaC profile image

AliciaC 4 years ago from British Columbia, Canada Author

Thank you very much, editorsupremo. Yes, insulin is much better known by most people. The fact that glucagon also plays a role in controlling blood sugar is sometimes a surprise for people!


kashmir56 profile image

kashmir56 4 years ago from Massachusetts

Hi my friend, very interesting and useful information for those who may have had some of these symptoms of hypoglycemia .

Well done and vote up and more !!!

Have a awesome weekend my friend ! :-)


AliciaC profile image

AliciaC 4 years ago from British Columbia, Canada Author

Hi, Tom. Thank you for voting and for the comment! I hope that your weekend is wonderful too.


drbj profile image

drbj 4 years ago from south Florida

As you point out in this excellent article, Alicia, insulin is much more well known to the general public than the other pancreatic hormone, glucagon. Guess the former elicits more PR than the latter.


AliciaC profile image

AliciaC 4 years ago from British Columbia, Canada Author

Hi, drbj. Thank you very much for the comment. Insulin is certainly a very important hormone, but people often forget - or don't realize - that glucagon is insulin's partner, and that both hormones are needed to keep the blood sugar level constant!


prasetio30 profile image

prasetio30 4 years ago from malang-indonesia

Very informative hub. Again...I learn many things from this hub. Voted up and useful. Take care :-)

Prasetio


AliciaC profile image

AliciaC 4 years ago from British Columbia, Canada Author

Thanks, Prasetio. I appreciate your visit, the comment and the votes!


Pollyannalana profile image

Pollyannalana 4 years ago from US

My dad died from complications linked to diabetes. I gave him his shots for years. There are foods that can help fight sugar like lentils and barley for example. I think anything we can find in the natural could be what will save our lives and maybe not die the horrible death my dad did.


AliciaC profile image

AliciaC 4 years ago from British Columbia, Canada Author

I am so sorry that you lost your father from diabetes complications, Pollyannalana. Thank you for sharing the dietary information - anything that can help diabetics is very useful, especially when it's a healthy food like lentils or barley.


tirelesstraveler profile image

tirelesstraveler 3 years ago from California

Your writing is easy to follow and engaging even when the topics are complex. The pictures of the pancreas are amazing.


AliciaC profile image

AliciaC 3 years ago from British Columbia, Canada Author

Thanks, tirelesstraveler. I appreciate your visit and comment!

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