More than 18 million Americans are estimated to have diabetes, including more than 5 million who are undiagnosed.

About 90 percent of U.S. diabetics have type 2 diabetes. The disease occurs when the body is unable to produce enough insulin and use it effectively to move glucose, a type of sugar, from the blood into cells, where it is used for energy. This condition is made worse by obesity and inactivity.

Another 16 million people have "pre-diabetes," a condition in which blood-sugar levels are higher than normal but not quite high enough for a diagnosis of diabetes. This condition often progresses to full diabetes.

Vernon says the Atkins method can help prevent that.

"You can change your metabolism by changing what you put on your plate," she says.

In simple terms, she says, "using the Atkins approach to manage diabetes is very effective because the carbohydrates you put in your mouth ... tell the body to make more insulin, and that's the pathway to the epidemic of overweight, obesity and diabetes."

Nathaniel Clark, of the American Diabetes Association and a registered dietitian, is skeptical. But he acknowledges that carbohydrates affect insulin levels, and that a reduction in carbohydrates may lower the need for insulin-boosting medications.

"The question is, is this the kind of diet you can live with long-term? If so, that's fine. But for most people, carbohydrates are an important part of the diet," he says. "To say, give up bread, pasta, potatoes, corn, is going to be reasonable only in the short term."

Studies have compared low-carb diets with more traditional low-fat diets and found that after six months, the low-carb eaters lost more weight. After 12 months, the difference vanished, but the low-carb group had increased insulin sensitivity, a measure of the body's ability to use insulin efficiently, says Samuel Klein of Washington University in St. Louis.