All About Insulin: By Naomi Cook

Naomi Cook earned her bachelors in Animal Science from Cornell University and received her masters from NYU in Science Education. Currently Naomi teaches AP Biology in Wetchester, NY. She includes concepts from both Type 1 + 2 Diabetes in her core curriculum.

If you are Diabetic or you know someone who has Diabetes, then you might know how important a role the hormone insulin is. Insulin's main purpose is to help regulate the glucose levels in the human body. Glucose levels rise in accordance to food intake, and can rise faster with the consumption of sugar or simple carbohyrdrates. Unfortunately for Type 1 Diabetics, the pancreas cells do not produce insulin, and therefore it must be injected.

Considering its importance, insulin is a relatively small and simple protein. Insulin is only made up of 51 amino acids. Genes, which are made up of your DNA and packaged in the chromosomes you inherit from your parents, contain the instructions to make proteins in your body. The gene that contains instructions for insulin protein is located on the eleventh chromosome of humans. This gene should actively produce insulin in the cells of the pancreas.

So where do we get insulin for injection? Up until 1982, insulin for Diabetics came from pigs and cows. Bovine and porcine pancreases were ground up and the insulin was purified and sold to Diabetics. This created inflammation at the site of injection, because the insulin was not compatible with the human’s immune system. In addition, inherent molecular differences between human and pig or cow insulin meant the response of the human were not as optimal as it could have been. Finally, retrieving insulin from slaughtered cows and pigs is just not the most efficient way of harvesting a protein for pharmaceutical purposes.

Since genes are made of DNA, the relatively recent advances in our knowledge of DNA have meant that we are able to produce insulin more easily. In 1982, we started using recombinant DNA technology to harvest insulin. Scientists identified and isolated the insulin producing gene on the eleventh chromosome of humans. Next, scientists turn to plasmids. Plasmids are small, circular pieces of DNA that can contain several genes and are naturally found in bacterial cells. Unlike us, bacterial cells can easily accept these plasmids, and once they have accepted the plasmid, the bacteria will produce the proteins that are coded for by the genes in the plasmid. Scientists use restriction enzymes to cut open the plasmid. Then, they can take the human insulin gene and literally paste it into the plasmid using ligase enzymes.

Through a process called transformation, bacteria can be induced to accept the plasmid into their cell. Once the plasmid is in the bacteria, that bacteria will begin producing human insulin. This insulin can then be purified and packaged for therapeutic purposes. What’s more, scientists have been able to create insulin analogs, which are slower acting and better able to regulate blood glucose levels throughout the day of the diabetic. The next time you take your insulin, say a little thank you to that bacteria (probably E. Coli) that is working so hard for you.

Considering how far we have come with producing effective insulin therapeutics cheaply and effectively over the past thirty years, let’s hope that funding for genetics research will continue and we will develop an effective treatment or cure for Diabetes.

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All About Carbohydrates: By Naomi Cook

Naomi Cook earned her bachelors in Animal Science from Cornell University and received her masters from NYU in Science Education. Currently Naomi teaches AP Biology in Wetchester, NY. She includes concepts from both Type 1 + 2 Diabetes in her core curriculum.

It’s virtually impossible to eat any food that doesn’t contain carbohydrates. This is because all biomass on Earth has its origins in photosynthesis, which produces glucose. It’s also impossible to sustain oneself on a diet that excludes all carbohydrates, since glucose is the main molecule from which a living organism derives its energy for life functions. Why then has it developed such a bad reputation? Probably because diets that are high in simple sugars, a type of carbohydrate, are linked to obesity and the onset of Type 2 Diabetes. And considering that 23.1 percent of the US population 60 years and older suffer from Diabetes, it makes sense that we are hearing a lot about carbohydrates. (National Institute of Diabetes and Digestive and Kidney Diseases)

But information on carbohydrates seems confusing to me. Molecularly, carbohydrates come in many different forms, and our bodies process, store and use each form differently. Depending on the type of carbohydrate we are ingesting, our hormones will respond very rapidly, which is usually not so good, more slowly which is better, or not at all, as is the case with a Diabetic. This makes it difficult to know exactly what a nutrition label means for your body when it says that it contains 23 grams of carbohydrates.

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The molecular building blocks of carbohydrates are simple sugars like sucrose (table sugar) and glucose (the product of photosynthesis). Plants synthesize much longer chains of simple sugars for storage. An example of a storage carbohydrate is starch. They will also synthesize longer chains of simple sugars for structural purposes. An example of this is fiber. When we eat food that lists carbohydrates on its nutrition label, we are probably eating a combination of simple sugars and more complex carbohydrates.
Simple sugars will be absorbed quickly into the blood. In order to respond to the rapid rise in blood glucose levels, the pancreas must respond quickly by producing large amounts of insulin. Over time, the spikes in insulin causes cells to become unresponsive to the insulin and Type 2 Diabetes may develop. The more processed a food is, the more simple sugars it tends to contain. Manufacturers add it to food so that it tastes better. Unfortunately, nutrition labels often do not distinguish between added sugars and carbohydrates that are found naturally in foods.

Longer chains of sugars which may be referred to as complex carbohydrates must be broken down in the digestive system and are generally released into the blood more slowly. This is less stressful on the body. The less processed a food is, the more slowly its constituent sugars seem to be released into the blood stream. Whole grains, fruits and low starch vegetables are broken down and released slowly, causing gradual increases in blood sugar. (Harvard School of Public Health)

Humans are unable to digest fiber, the carbohydrate constituent of a plant’s cell wall. As a result, these sugars are never released into the blood stream and do not add to the calorie content of a food. They do however bind to fats in the intestines, carrying fatty substances out as waste, and contribute to a person feeling full. Therefore, when looking at the nutrition label, it is important to take the fiber content into consideration when looking at the overall carbohydrate content. Fiber does not increase blood glucose levels.

Since the rate at which sugars are released into the blood seems to play an important role in how much stress your body experiences after a meal, scientists have begun to categorize foods based on their glycemic index. For example, potatoes are filled with the complex carbohydrate starch, which seems to be broken down and released as simple sugars into the blood just as quickly as the added simple sugars from a processed food product enter the blood stream. Foods with a lower glycemic index release their sugars more slowly than foods with a higher glycemic index. While it is still debatable whether or not foods with a high glycemic index can be linked to things like Type 2 Diabetes or obesity, it is a unique way of analyzing different foods. It does not however, take into account carbohydrate density of foods. For example, watermelon has a high glycemic index, but its carbohydrate density is so low, that it ends up releasing very little sugar into the blood. (Harvard School of Public Health) A comprehensive glycemic index of foods may be found at http://www.glycemicindex.com/.

When planning meals, it is still helpful to just go with the nutrition label. The American Diabetes Association recommends that Diabetics take 45-60 grams of carbohydrates per meal. (American Diabetes Association) Foods that contain carbohydrates, whether complex or simple, need to be taken into account when Diabetics are planning meals. These foods are breads, cereals, crackers, rice, fruit, yogurt, juice, milk, beans and soy products, potatoes, corn, sweets and juice. Non-starchy vegetables such as lettuce and peppers do contain carbohydrates, but very little in comparison. (American Diabetes Association) Again, it is probably best for as many of those 45-60 grams of carbohydrates to be from unprocessed foods such as whole grains, fruits, vegetables and beans.

The American Diabetic Association has an incredibly helpful interactive website that allows users to find the nutrition information on almost any natural and many processed foods. It also allows the user to create meals by adding ingredients and changing serving sizes to view the total nutrition content of the full meal. Nutrition content of foods can be directly compared, and the website can find healthier alternatives to ingredients. I have found it helpful even though I am not a Diabetic. You may access the link here. Happy eating!

Work Cited
American Diabetes Association. "Carbohydrate Counting." February, 2009.

Harvard School of Public Health. "Carbohydrates: Good Carbs Guide the Way." February, 2009.

National Institute of Diabetes and Digestive and Kidney Diseases. National Diabetes Statistics, 2007 fact sheet. Bethesda, MD: U.S. Department of Health and Human Services, National Institutes of Health, 2008.

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Diabetes 101 - By Naomi Cook

Naomi Cook earned her bachelors in Animal Science from Cornell University and received her masters from NYU in Science Education. Currently Naomi teaches AP Biology in Wetchester, NY. She includes concepts from both Type 1 + 2 Diabetes in her core curriculum.

Diabetes is literally a disorder that results in increased urination. This can be directly caused by a higher than normal blood glucose (sugar) level, as the kidneys work harder to rid the body of the excess glucose. The hormone insulin is produced by the pancreas and acts like a chemical messenger that instructs cells to allow glucose in. Once in the cell, glucose can be oxidized to release energy for life functions or it can be stored in the cells of the liver as a molecule called glycogen. When insulin is produced and cells are responding to it properly, blood glucose levels are stable. When a person’s cells become either unable to respond to insulin or unable to produce insulin, blood glucose levels increase and Diabetes results. There are two types of Diabetes, Type I and Type II.

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Type I Diabetes occurs when the body stops producing insulin, usually during childhood. The Type I Diabetic injects insulin in order to regulate his or her own blood glucose level. There is currently no cure for Type I Diabetes. Type II Diabetes occurs when the body continues to produce insulin, but cells become unresponsive to the insulin. Therefore, Type II Diabetics do not take insulin. Instead, they regulate their blood glucose levels through diet and exercise. Unlike Type I, Type II Diabetes usually develops in adulthood.

In Type I Diabetes, the insulin producing cells of the pancreas called the Islets of Langerhans, are attacked by the person’s own immune system. We do not know why this happens yet, but it usually occurs in childhood and scientists think that it may be linked to genetics or viral infections. As a result, that person stops producing insulin, and blood glucose levels increase. This is called hyperglycemia and occurs when a Type I Diabetic eats a large meal. The person will experience increased urination, thirst, fatigue, blurry vision and nausea. In order to prevent this, he or she injects insulin, which will lower blood glucose.

If too much insulin is taken, hypoglycemia (low blood sugar) can occur. This is process is exaggerated with either not enough food intake or when the person engages in physical activity. The symptoms of hypoglycemia are sweating, shakiness, hunger and dizziness. If not treated, hypoglycemia can result in slurred speech, drowsiness, confusion and in its worst case, diabetic coma as the organs of the body shut down because they are starved for glucose. The most effective treatment is ingesting anything with high levels of sugar such as juice or candy.

A condition called ketoacidosis may also result because cells are not getting the glucose they need. This can happen if the Diabetic is not taking his or her insulin and glucose is not able to enter into the cell. Cells will begin to excessively utilize fats and proteins for energy. Unfortunately, the byproducts of this reaction are ketones, which are toxic to the body.

The Type I Diabetic is responsible for lowering blood glucose after a meal by injecting insulin, but not letting it get so low that hypoglycemia begins to happen. It’s a difficult task. Because insulin is a peptide (a small protein) it can not be taken as a pill. Proteins are digested into their amino acid building blocks in the stomach, before the Diabetic can absorb the insulin into the blood stream. Therefore, it must be injected, making treatment even more complicated, but extremely important.

If not controlled, the short term effects of hypoglycemia can be dramatic and dangerous. The long term effects of hyperglycemia can seriously affect quality of life. Damage to the tissue of the heart can lead to heart attack, stroke and high blood pressure. Damage to blood vessels serving the retina can lead to blindness. Nerve damage in the leg may lead to tingling, numbness and an inability for wounds to heal. Nerve damage to the kidneys can result in kidney failure.

In Type II Diabetes, the person’s cells become unresponsive to insulin, even though the pancreas continues to produce it. Similar to Type I Diabetes, blood glucose levels will increase. Because cells are unresponsive to insulin, Type II Diabetics do not control their sugar by taking insulin. They must do so through diet and exercise. As Type II Diabetes progress, the pancreas continues producing insulin even though cells remain unresponsive, and can eventually become overwhelmed. At this point, the Islets of Langerhans stop producing insulin and the Diabetic may need to start insulin treatment. Type II Diabetics can suffer from hyperglycemia and will also suffer from hypoglycemia if they are on glucose lowering medications. If blood glucose is not regulated, the long term effects of hyperglycemia will damage tissue just as it does with the Type I Diabetic.

Although the exact mechanism for developing Type II Diabetes is unknown, certain factors seem to increase the likelihood that a person’s cells will become unresponsive to insulin. Excess fatty tissue and inactivity is linked to Type II Diabetes. Unlike Type I Diabetes, a person’s risk increases with age. There also appears to be a genetic link to Type II Diabetes. A person’s risk increases if a sibling or parent has the disease, and certain races such as Asians Americans, Native Americans, Hispanics and Blacks have higher incidences of Type II Diabetes.

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