Glucagon and Hypoglycemia: Hormonal Control of Blood Sugar

Updated on September 24, 2017
AliciaC profile image

Linda Crampton is a writer and teacher with a first class honors degree in biology. She often writes about the scientific basis of disease.

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

Role of the Pancreas and Liver in Controlling Blood Sugar

Both the pancreas and the liver play a role in controlling blood sugar. 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 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

Hormones

Like insulin, glucagon is a peptide hormone and is made of amino acids. A glucagon molecule is a chain of twenty-nine amino acids. Hormones are chemical messengers that travel from their site of origin to their target organ through the blood. When they reach the target, they bind to receptors on the surface of cells. Receptors are proteins on or in the cell membrane that cause a specific effect when they join to the correct molecule.

Control of Blood Sugar by Insulin and Glucagon

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 glucose level in the blood is too high, insulin is released from the pancreas and binds to receptors on cell membranes. This process triggers the passage of glucose into the cells, including those of the liver. Excess glucose is stored in the liver as glycogen. When the blood sugar level is too low, glucagon is released from the pancreas. It binds to liver cells and stimulates the liver to produce glucose by two methods: glycogenolysis and gluconeogenesis.

Glycogenolysis

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. The term may be easier to remember if a person realizes that in biology "lysis" means the breaking down of a structure or substance.

Gluconeogenesis

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. "Genesis" means creation and "neo" means new. The term gluconeogenesis refers to the creation of new glucose molecules.

Comparison of Glucagon and Insulin

Hormone
Origin
Function
Notes
Glucagon
Alpha cells of pancreatic islets
Raises blood sugar
Triggers glyogenolysis and gluconeogenesis
Insulin
Beta cells of pancreatic islets
Lowers blood sugar
Triggers the entry of glucose into cells

Glucagon, Insulin, and Blood Sugar Level

Hypoglycemia in Type 1 Diabetics

Type 1 diabetes is a disorder in which the pancreas no longer makes insulin or makes only a tiny amount. It's an autoimmune condition. The patient's immune system mistakenly attacks and destroys the beta cells in the pancreas. The disorder is generally treated with insulin injections. The timing and quantity of insulin that is injected is vitally important. Too little or too much insulin in the bloodstream in relation to blood sugar level can both be dangerous.

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 type 1 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.

When people with diabetes develop hypoglycemia, their body may not be able to produce enough glucagon to compensate for the lowered glucose level, or it 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 to prevent a problem from developing when their glucose level falls or rises.

Possible Symptoms of Hypoglycemia

Some common symptoms of hypoglycemia include the following:

  • 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 they may experience seizures or a coma.

Severe Diabetic Hypoglycemia

Anyone who suspects that they experience periodic episodes of hypoglycemia should visit a doctor for a diagnosis and treatment recommendations.

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 the severe version of the condition, 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 Type 2 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 often resistant to the hormone's presence and no longer fully respond to it. This prevents sufficient glucose from entering the cells. In some cases the disorder appears when the pancreas is unable to make enough insulin for the body's needs.

People with type 2 diabetes are generally treated with lifestyle changes, medications, and sometimes insulin injections. Patients may sometimes develop mild hypoglycemia and occasionally a severe form of the disorder which requires glucagon administration. People with type 2 diabetes are less likely to require supplemental glucagon than those with type 1 diabetes, however.

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

Current 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 a smaller protein called proglucagon. This in turn breaks down into even 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 type 1 diabetes and insulin is definitely an essential treatment for the disorder. However, researchers suspect that the interactions 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.

References

Questions & Answers

    © 2012 Linda Crampton

    Comments

      0 of 8192 characters used
      Post Comment

      • AliciaC profile imageAUTHOR

        Linda Crampton 

        4 years ago from British Columbia, Canada

        Thanks, tirelesstraveler. I appreciate your visit and comment!

      • tirelesstraveler profile image

        Judy Specht 

        4 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 imageAUTHOR

        Linda Crampton 

        5 years ago from British Columbia, Canada

        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.

      • Pollyannalana profile image

        Pollyannalana 

        5 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 imageAUTHOR

        Linda Crampton 

        5 years ago from British Columbia, Canada

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

      • prasetio30 profile image

        prasetio30 

        5 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 imageAUTHOR

        Linda Crampton 

        5 years ago from British Columbia, Canada

        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!

      • drbj profile image

        drbj and sherry 

        5 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 imageAUTHOR

        Linda Crampton 

        5 years ago from British Columbia, Canada

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

      • kashmir56 profile image

        Thomas Silvia 

        5 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 imageAUTHOR

        Linda Crampton 

        5 years ago from British Columbia, Canada

        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!

      • editorsupremo profile image

        editorsupremo 

        5 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 imageAUTHOR

        Linda Crampton 

        5 years ago from British Columbia, Canada

        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.

      • mperrottet profile image

        Margaret Perrottet 

        5 years ago from San Antonio, FL

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

      • AliciaC profile imageAUTHOR

        Linda Crampton 

        5 years ago from British Columbia, Canada

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

      • GoodLady profile image

        Penelope Hart 

        5 years ago from Rome, Italy

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

      • AliciaC profile imageAUTHOR

        Linda Crampton 

        5 years ago from British Columbia, Canada

        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.

      • billybuc profile image

        Bill Holland 

        5 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.

      working

      This website uses cookies

      As a user in the EEA, your approval is needed on a few things. To provide a better website experience, healdove.com uses cookies (and other similar technologies) and may collect, process, and share personal data. Please choose which areas of our service you consent to our doing so.

      For more information on managing or withdrawing consents and how we handle data, visit our Privacy Policy at: https://healdove.com/privacy-policy#gdpr

      Show Details
      Necessary
      HubPages Device IDThis is used to identify particular browsers or devices when the access the service, and is used for security reasons.
      LoginThis is necessary to sign in to the HubPages Service.
      Google RecaptchaThis is used to prevent bots and spam. (Privacy Policy)
      AkismetThis is used to detect comment spam. (Privacy Policy)
      HubPages Google AnalyticsThis is used to provide data on traffic to our website, all personally identifyable data is anonymized. (Privacy Policy)
      HubPages Traffic PixelThis is used to collect data on traffic to articles and other pages on our site. Unless you are signed in to a HubPages account, all personally identifiable information is anonymized.
      Amazon Web ServicesThis is a cloud services platform that we used to host our service. (Privacy Policy)
      CloudflareThis is a cloud CDN service that we use to efficiently deliver files required for our service to operate such as javascript, cascading style sheets, images, and videos. (Privacy Policy)
      Google Hosted LibrariesJavascript software libraries such as jQuery are loaded at endpoints on the googleapis.com or gstatic.com domains, for performance and efficiency reasons. (Privacy Policy)
      Features
      Google Custom SearchThis is feature allows you to search the site. (Privacy Policy)
      Google MapsSome articles have Google Maps embedded in them. (Privacy Policy)
      Google ChartsThis is used to display charts and graphs on articles and the author center. (Privacy Policy)
      Google AdSense Host APIThis service allows you to sign up for or associate a Google AdSense account with HubPages, so that you can earn money from ads on your articles. No data is shared unless you engage with this feature. (Privacy Policy)
      Google YouTubeSome articles have YouTube videos embedded in them. (Privacy Policy)
      VimeoSome articles have Vimeo videos embedded in them. (Privacy Policy)
      PaypalThis is used for a registered author who enrolls in the HubPages Earnings program and requests to be paid via PayPal. No data is shared with Paypal unless you engage with this feature. (Privacy Policy)
      Facebook LoginYou can use this to streamline signing up for, or signing in to your Hubpages account. No data is shared with Facebook unless you engage with this feature. (Privacy Policy)
      MavenThis supports the Maven widget and search functionality. (Privacy Policy)
      Marketing
      Google AdSenseThis is an ad network. (Privacy Policy)
      Google DoubleClickGoogle provides ad serving technology and runs an ad network. (Privacy Policy)
      Index ExchangeThis is an ad network. (Privacy Policy)
      SovrnThis is an ad network. (Privacy Policy)
      Facebook AdsThis is an ad network. (Privacy Policy)
      Amazon Unified Ad MarketplaceThis is an ad network. (Privacy Policy)
      AppNexusThis is an ad network. (Privacy Policy)
      OpenxThis is an ad network. (Privacy Policy)
      Rubicon ProjectThis is an ad network. (Privacy Policy)
      TripleLiftThis is an ad network. (Privacy Policy)
      Say MediaWe partner with Say Media to deliver ad campaigns on our sites. (Privacy Policy)
      Remarketing PixelsWe may use remarketing pixels from advertising networks such as Google AdWords, Bing Ads, and Facebook in order to advertise the HubPages Service to people that have visited our sites.
      Conversion Tracking PixelsWe may use conversion tracking pixels from advertising networks such as Google AdWords, Bing Ads, and Facebook in order to identify when an advertisement has successfully resulted in the desired action, such as signing up for the HubPages Service or publishing an article on the HubPages Service.
      Statistics
      Author Google AnalyticsThis is used to provide traffic data and reports to the authors of articles on the HubPages Service. (Privacy Policy)
      ComscoreComScore is a media measurement and analytics company providing marketing data and analytics to enterprises, media and advertising agencies, and publishers. Non-consent will result in ComScore only processing obfuscated personal data. (Privacy Policy)
      Amazon Tracking PixelSome articles display amazon products as part of the Amazon Affiliate program, this pixel provides traffic statistics for those products (Privacy Policy)