A disordered thermostat

Understanding the delicate balance of glucose metabolism

Bill Snyder
Published: July, 2003

An image taken with a confocal microscope shows the inside of a insulin-producing beta cell in remarkable detail. The nucleus is the dark spot, upper left. Stained with green fluorescent protein, the mitochondria, which are involved in generating energy for the cell, are yellow, while the Golgi vesicles, which help direct secretory proteins to their proper locations in the cell, are blue.
Courtesy of David Piston, Ph.D. Vanderbilt University
In 2002, the landmark Diabetes Prevention Program showed that moderate exercise and weight loss reduced by 58 percent the incidence of type 2 diabetes in people at high risk for developing the disease.

The problem is that few people have access to the intensive diabetes management provided to the study participants.

There also is growing evidence that some people are genetically susceptible to becoming obese and developing type 2 diabetes, and no matter how hard they try to lose weight, their bodies are working against them. “It’s extraordinarily difficult,” Rudolph Leibel, M.D., who co-discovered the fat hormone leptin.

A variety of medications, including those used to treat heart disease and lower cholesterol, can help prevent diabetes. But many of these drugs have side effects, and they don’t work in all patients.

Thanks in large part to the genetic and computer revolutions of the past 30 years, there has been a flood of new information about diabetes and obesity. Much of it at this point is incomplete. But progress is definitely being made.

First, a few definitions:

Glucose, a form of sugar primarily supplied by the diet, is a major fuel for the body and virtually the only source of energy for the brain. Because it’s so vital, extra glucose is stored in the liver and muscle in the form of glycogen. The liver also can make glucose from raw materials if an emergency supply is needed.

Insulin is secreted by “beta” cells, one of four types of cells that are clumped together in “islets” in the pancreas. One of its main jobs is to activate a pathway of biochemical signals that ultimately moves glucose from the bloodstream into muscle.

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