The food we eat gets broken down into three basic groups:
In different parts of the intestine these compounds get broken down or digested even further. Sugar or glucose is absorbed from the intestine into blood. The blood carries glucose around the body and cells can then pull in glucose from the blood using specialized proteins called glucose transporters. Once inside the cell, glucose can be "burnt" to release energy.
Because cells are very dependent on glucose for energy, the body tries to maintain blood sugar levels within a normal range using the hormone insulin. When the body doesn't take in enough food, the liver and kidneys try to maintain blood sugar by breaking down stored starch or protein and converting them into glucose. After a meal, blood sugar usually rises and the excess glucose gets stored in fat and muscle cells. This storage is made possible because of the glucose transport proteins, especially one called Glut4.
When cells are exposed to insulin they activate the glucose transporters to take in sugar. When this process gets disrupted, that is, when cells become less sensitive to the effect of insulin, a condition called insulin resistance develops. The development of insulin resistance is usually the earliest sign of the beginning of diabetes.
In this issue of TreatmentUpdate, we review some of the recent findings on insulin and protease inhibitors by research teams in Canada, France, Israel and the U.S. Although the focus of much of that work is on the protease inhibitor indinavir (Crixivan), readers should note that all protease inhibitors, including Kaletra (lopinavir), have the potential to cause insulin resistance.
REFERENCES
1. Mueckler M. Insulin resistance and the disruption of Glut4 trafficking in skeletal muscle. Journal of Clinical Investigation 2001;107(10):1211-1213.
2. Hruz PW, Murata H and Mueckler M. Adverse metabolic consequences of HIV protease inhibitor therapy: the search for a central mechanism. American Journal of Physiology – Endocrinology and Metabolism 2001:280:e549-e553.
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Copyright © 2001 - TreatmentUpdate. Reproduced with permission. Reproduction of this article (other than one copy for personal reference) must be cleared through the Editor, The Canadian AIDS Treatment Information Exchange, 555 Richmond St. West, Suite 505, Box 1104, Toronto, ON, M5V 3B1 • Phone: 416-203-7122 • Toll Free: 1-800-263-1638 • Fax: 416-203-8284 http://www.catie.ca.
AEGiS is made possible through unrestricted grants from Boehringer Ingelheim, Elton John AIDS Foundation, iMetrikus, Inc., the National Library of Medicine, and donations from users like you. Always watch for outdated information. This article first appeared in 2001. This material is designed to support, not replace, the relationship that exists between you and your doctor.
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