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Insulin: Breaking it Down

cmcgowan's picture


When you reach fora piece of candy, what do you think about?  I can almost guarantee that you aren’t thinking about howyour body is going to break down the sugar and starches in that candy to createthe energy that you need to carry out basic functions. Because eating anddigesting has always been a part of life, most of us probably haven’t reallythought about what happens after we put something into our mouths.  Most people don’t realize that nothaving to think about this is a luxury. My brother Kilty has to think about every single thing that he puts intohis mouth. This is because since the age of 3, Kilty has had Type 1 Diabetes.This means that his body is unable to produce insulin, the hormone that isnecessary to convert food into energy. Before he eats anything, Kilty has toinject the necessary amount of insulin so that his body will react normally toit.

 I was initially intending to write thispaper on diabetes as a disease, however as I started my research I realizedthat I already know what diabetes is. I know what it is about my brother’s bodythat makes him unable to produce insulin, however what I don’t know a lot aboutis the insulin that he injects into his body every time he eats.  Just as I have always assumed that mybody will deal with the food that I eat, I have assumed that insulin is aresource that will always be available to my brother. I have no idea how itworks--I just know that it does. It is somewhat alarming to realize that I don’t understand thissubstance that is literally keeping my brother alive.  I wantto know when and how insulin was discovered, how it works, how it has changedand what would happen without it.

In order to fullyunderstand and answer my questions about insulin, I first have to learn aboutthe understanding of diabetes itself. When and how did scientists begin tounderstand diabetes? Although historians have found records mentioningdiabetes-like symptoms among the artifacts of ancient Egyptians, Indians andPersians, major developments in the knowledge of diabetes did not occur untilthe late 1800’s(1). In 1869, a German medical student made one of the mostimportant discoveries in diabetes history.  Paul Langerhans discovered that in the pancreas there aretwo different types of tissues. Langerhans knew that the function of one ofthese types of tissues was to secrete pancreatic juice and allow for thedigestion of food, but he was unsure of the other type of tissue (2). 

Throughout thelate 1800’s and into the early 1900’s many other scientists researched thegroups of cells located in the other type of tissue.  To better understand these groups of cells, which becameknown as the  “islets of Langerhans,”scientists experimented with dogs. What they found was that when they removedthe islets, the dogs developed diabetes (3). Researchers were unsure why thiswas until the early 1920’s. A Canadian scientist, Frederick Bantinghypothesized that there was an anti-diabetic agent within the Islets ofLangerhans. With the help of another scientist, Charles Best, Banting testedhis hypothesis by tying up the pancreatic duct of dogs without diabetes. Aftera few months, all of the pancreatic juice and digestive enzymes had died andonly the islets of Langerhans were left. Banting and Best then extracted thepancreatic gland, ground it up and combined it with saline. They injected thesolution into a dog suffering diabetes and the dog quickly improved (4). Thissolution was the first form of what we now call insulin.

 Once insulin is injected, it works justlike the insulin that is naturally produced in those without diabetes. Theinsulin allows the body to utilize glucose for energy. Without insulin, the amountof glucose in the body builds up and the body begins to metabolize fat andproteins. When the blood glucose level gets extremely high, the body goes intoketoacidosis, which is potentially fatal. This is why those with diabetes haveto frequently check their blood sugar. When they have an unusually high bloodsugar, they also usually have to check their ketone levels. I remember mybrother having to do this a few times when I was younger but I never reallyunderstood what ketones were. The liver produces ketones when fat ismetabolized and glucose is not being broken down for energy.  As a result the bloods ph levelincreases and this is what ketoacidosis is (5).

Even thoughBanting and Best made a breakthrough in the lab, a lot of development was neededbefore there could be a safe and effective form of insulin for humans. Thefirst marketed forms of insulin were typically made from cows and pigs, andwere short-acting (6). Today there are many different kinds of insulin thatwork at many different speeds. Before doing research I assumed that thepractice of getting insulin from animals was out of date, but I was wrong.Animal insulin is still used today, although it is not the most commonform.  In the latter part of the 20thcentury, scientists were able to create “human insulin.”  The process by which “human insulin” ismade is quite different than animal insulin. Instead of using purified pancreasextracts, scientists use recombinant DNA technology to transfer the human genefor making insulin into a simple cell like yeast or bacteria (7).

 The most common and effective way toadminister Insulin is by syringe. When I was younger I never understood why mybrother had to give himself so many shots every day. I was curious as to why hecouldn’t just put the insulin in his food or why he couldn’t take it as a pill.Insulin has to be injected using a syringe because it is a protein. If it wereswallowed it would just be broken down by the digestive system and it would notbe able to carry out its intended job (8). Many people with diabetes now havethe option to use an insulin pump, which is attached to the body at all times.

It is amazing howmuch development has been made in the world of diabetes in the past century.Before the development of insulin, diabetes was essentially a death sentence.Hospitals had wards full of diabetics who were slowly starving to death. Nowthanks to insulin, my brother and many others can live long, healthy lives withdiabetes. As I mentioned earlier in my paper, I chose to write about insulinbecause I thought I understood diabetes. In writing this paper, I actuallylearned so much more about diabetes. I guess that goes to show that you neverreally understand something until you break it down and look at how individualpieces fit into the larger picture.




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