Insulin
Insulin is a hormone that is excreted by the pancreas. We think of insulin as being the regulator for blood sugar, but it also has many other jobs. Insulin is also responsible for fat, protein and magnesium storage and helps to build muscle tissue.
Insulin controls many processes in the body. It tells your brain that you are hungry and need to eat when your blood sugar levels get low. If you have insulin resistance, it causes things to go from bad to worse. It increases LDL (bad) cholesterol and triglycerides and lowers HDL (good) cholesterol levels. It causes your blood pressure to rise. It causes your platelets to stick together (think of a scab forming on a wound--that is the job of platelets and fibrin.) It causes inflammation in your arteries, and cholesterol plaques start to build up in them.
Insulin and Metabolism
When you eat carbohydrate foods such as bread, potatoes, rice, beans and vegetables, your body quickly breaks them down in your intestines into a basic sugar called glucose. Glucose is what the body uses for fuel. This glucose that is now circulating in your blood is used by the cells for energy.
If there is more glucose than is immediately needed for energy, it is stored in the liver and muscle tissue in a form called glycogen for use at a later time. When the liver and muscles have all of the glucose storage they can handle, the rest is stored as fat.
In order for the glucose to get into the cells, insulin is required. When glucose enters the blood stream, a message is sent to the pancreas to release insulin. There are little lock-like mechanisms on cells called receptors. When the right key is put into them, they open, allowing something to go in. In the case of glucose, insulin is the key that opens the cell door for glucose to enter in.
Insulin Resistance
Insulin resistance happens when the cells don't allow the insulin that is released to open the doors. This can be because there are not enough insulin receptors or the receptors that are there are not working properly.
If the doors of the cells don't open and allow the glucose to go in, the cells don't have fuel available to them for use as energy, so a message is sent to the pancreas to send more insulin. The cells that are hungry for glucose cause a message to be sent to the liver to release glycogen in the form of glucose--now there is more glucose and more insulin in the bloodstream.
Because there are still some receptors working, some insulin does open some doors allowing some glucose to enter the cells--but insulin and glucose levels have built up in the bloodstream causing many problems that result in the Metabolic Syndrome.
Image by ADAM Inc.Sources:
- American Association of Diabetes Educators. (2003). Diabetes and complications. (5th ed.). Chicago: American Association of Diabetes Educators.
- Canadian Association of Cardiac Rehabilitation. (2000). An interview with Gerald Reaven: Syndrome X: The risks of insulin resistance. [online]. Accessed November 18, 2006.
- National Diabetes Information Clearinghouse (NDIC). (2006, August). Insulin resistance. [online]. Accessed November 23, 2006.
- Stanford University School of Medicine General Clinical Research Center. (2003). Insulin resistance. [online]. Accessed November 17, 2006.