Glucose and insulin are two chemicals found in the body. Glucose is an energy source for the body, and generally the main energy source. Insulin is a hormone, meaning a chemical that is released into the blood to make changes in other parts of the body. It regulates levels of glucose in the blood.
Sources of Glucose and Insulin
Glucose is a sugar molecule. Starchy foods such as breads, pasta and potatoes contain large chains of carbohydrates that are broken down into glucose. Glucose is also found in candy. Table sugar is sucrose, which is composed of a molecule of the sugar glucose attached to another sugar, fructose. Both can be used by the body for energy, but fructose undergoes a slightly different metabolism.
According to the book "Physiology" by Linda Costanzo, insulin is a hormone made of protein that is synthesized in specialized cells in the pancreas. The pancreas is an organ that functions to aid in digestion and is located in the middle of the abdomen.
Function of Glucose
The energy in glucose and other molecules, plus oxygen, is transferred to a chemical called adenosine triphosphate, or ATP, where it is stored and subsequently used for cellular activity. This activity can include contraction of the fibers in muscle cells, for example.
In addition, individual glucose molecules can be linked together by the body to form glycogen. Glycogen is used to store glucose in the liver and muscles for later use.
Function of Insulin
Insulin levels normally rise with a meal. Food raises the levels of nutrients in the body, including glucose. Insulin released by the pancreas signals cells to take up glucose out of the blood stream. So, as the levels of glucose rise in the blood, the insulin acts to lower the blood glucose level.
In the cells, the glucose is used for energy or stored as glycogen. Without insulin, the glucose would remain in the blood and the cells would not have as much energy available.
Hyperglycemia
According to "Harrison's Principles of Internal Medicine" by Anthony S. Fauci, MD, diabetes mellitus is a disorder that results in high levels of blood glucose, called hyperglycemia. There are two main forms. In type 1 diabetes, the immune system disrupts the ability of the pancreas to release insulin. It tends to occur in younger people. Since the disease results in a lack of insulin, the treatment is to administer insulin. It must be given by injection because insulin is a protein. If swallowed like a pill, it will be digested by the stomach.
Type 2 diabetes is slower in onset. It tends to occur in middle-aged to older persons and is strongly associated with obesity. In type 2 diabetes, the pancreas makes insulin, but the cells do not respond to it. They do not take up glucose and so the levels of glucose in the blood remain high. This type is therefore also referred to as insulin-resistant diabetes mellitus. The treatment includes physical activity, weight loss, medications to lower the blood glucose, possibly including insulin.
Hypoglycemia
Hypoglycemia is a problem of low glucose. It can be caused by not eating enough. However, it is most likely to occur when a diabetic patient takes too much insulin. It can cause anxiety, sweating, tremor, confusion, weakness, vision changes, hunger and, if extreme or prolonged, coma or death. It is treated by the administration of glucose.
References
- "Physiology"; Linda S Costanzo; 4th ed. 2009
- "Harrison's Principles of Internal Medicine"; Anthony S. Fauci; 17th ed. 2008
