hat is Biology Good For?
Controlling Diabetes: Recombinant Human Insulin

(This assignment is optional. Read this essay and answer the questions at the bottom for 3 extra credit points. You may only turn in one per six weeks. The assignment is due one week before the end of the six weeks. It is not necessary to visit the links in the text unless you are interested in more information.)


What is Diabetes? Diabetes is a disease where the body is either unable to make the protein insulin, or is able to make insulin, but is unable to use insulin. This results in an inability to metabolize (break down) blood glucose and an inability to store glycogen (the storage form of glucose) in the liver.

Diabetes is a life-threatening disease. If left untreated, high glucose levels may damage a person's eyes, kidneys, nerves, or heart. Uncontrolled diabetes can lead to diabetic acidosis, in which toxic chemicals called ketones build up in the blood. Patients have sweet-smelling breath, and may suffer confusion, unconsciousness, and death.

Diabetes is common. At least one in every 16 people has diabetes; and more than 10 million individuals with diabetes around the world rely on insulin to control their diabetes.

What normally happens when a person (without diabetes) eats food?

1.  Some of the food breaks down into sugars; one of these sugars is glucose, the body's main fuel.
2.  Sugar enters the bloodstream, and the level of
blood sugar begins to rise.
3.  When the body senses an increase in
blood sugar, it sends a signal to the pancreas.
4.  The pancreas makes insulin and sends it into the bloodstream.
5.  Insulin lowers the level of
blood sugar by allowing sugar to pass from the bloodstream into the cells.
6.  The level of sugar in the bloodstream falls as the sugar passes into the cells.
7.  The body's cells use the sugar for fuel (ATP production). You feel energetic.

When a person has diabetes
, sugar stays in the bloodstream rather than entering cells because their body does not make or does not respond properly to insulin. They are unable to properly get energy from the food they eat. The symptoms of diabetes are hyperglycemia (elevated sugar levels in the urine and blood), increased urination, thirst, hunger, weakness, weight loss, and possibly death.

There are two main types of diabetes: type 1 and type 2.

In type 1 diabetes, the body makes little or no insulin - called insulin deficiency. People with this type of diabetes must take insulin shots to live. That's why it is referred to as "insulin-dependent diabetes." Less than one in ten people with diabetes have type 1. Although it usually begins when people are young, it may occur at any age.

In type 2 diabetes, the body makes insulin, but their cells cannot use it well. This is called insulin resistance. Usually, this results in the inability to make insulin as time goes by (insulin deficiency). People who have it can be treated with proper meal planning and exercise, oral medicines and/or insulin. Most people with type 2 diabetes eventually will need to take insulin to control their blood sugar levels. Type 2 diabetes is the most common form of diabetes and accounts for at least nine out of ten cases. Although diabetes can occur in younger people, it is most often acquired by people over 40 years of age.

Diabetes Medicine: recombinant Human Insulin.

Diabetes can be managed by various treatments, including the use of insulin treatment. In the 1920s, physicians began giving diabetic patients insulin purified from the pancreas of pigs (porcine insulin) or cows (bovine insulin). However, the few amino acid difference between human and pig or cow insulin caused patients' immune systems to produce antibodies against the foreign insulin, resulting in the medicine becoming ineffective.

In 1978, scientists at the Biotechnology Company Genentech cloned the gene for Human Insulin.

"Cloning" refers to the process of making multiple, identical, copies of a one gene. After the human insulin gene was isolated from human tissue, it was chemically joined or 'spliced' to into a small bacterial chromosome called a plasmid. Once joined to this plasmid DNA, it essentially became just another piece of DNA in the bacterial chromosome.

Every time the bacterial cell divides, it replicates its DNA, including replicating the human insulin gene DNA. The ribosomes in the E. coli cell translate the mRNA into human insulin just as it would translate any mRNA into its corresponding protein. The result: tons of bacteria making tons of human insulin! [Image]


Genentech licensed the human insulin technology to Eli Lilly, where it was named "Humulin" or Recombinant Human Insulin. In 1982, human insulin became the first recombinant DNA drug approved by FDA. Today, Humulin is made right here in Indianapolis in gigantic fermentation vats, 4 stories high and filled with bacteria!!! These fermentation vats operate 24 hours a day, year round. The human insulin protein made by the E. coli bacteria is collected from the vats, purified, and packaged for use by patients with diabetes.

Humulin is used by more than 4 million people with diabetes around the world every day. A related product called Humalog more closely mimics the body's natural insulin response after meals and is beginning to be a best selling insulin product. [Image]

Today, most daily injections of recombinant human insulin are delivered in easy 'pen' form that is disposible after use and does not require the use of a traditional syringe and vial for injection.

At this time, there is no "cure" for diabetes. It can be managed by taking insulin, carefully controlling diet and exercise, but it is a condition that lasts as long as the person lives.

: Most of this material, quotes, and images for this Good For comes from the following sources:
Eli Lilly and Company and
American Diabetes Association

The text of this "What is Biology Good For" exercise is copyrighted under the name of Dr. Kathleen A. Marrs, 1999, 2000, 2001, 2003. There are no restrictions on its use by educators or by non-profit institutions as long as its content not modified, proper copyright acknowledgement is retained, and this statement is not removed.



Extra Credit Questions: Please answer the following questions on a piece of paper and turn it into me.

1. What causes type 1 diabetes?
2. What are the
symptoms of diabetes?
3. Why is recombinant human insulin
better for diabetic patients than pig or cow insulin?