January 7, 2010
Incidence Of Type 1 Diabetes Doubles In 20 Years, Continues Rising At 3 Percent Per Year — But Why?
Book investigates leading scientific hypotheses to explain mysterious increase
The incidence of type 1 diabetes is now twice as high among children as it was in the 1980s, and 10 to 20 times more common than 100 years ago, according to peer-reviewed research uncovered in a new book from Kaplan Publishing.
Now veteran medical journalist Dan Hurley has gathered the evidence from published studies and investigative reporting in DIABETES RISING: How A Rare Disease Became A Modern Pandemic, And What To Do About It. Hurley, an award-winning reporter who has written often for the "Science Times" section of The New York Times, cites studies and analysis by some of the top researchers in the field documenting the long-term and ongoing rise.
Diagnosed with type 1 diabetes in 1975, when he was an 18-year-old college freshman, Hurley knew nobody else at the time with the disease, which was then remarkably rare. "Now I know three other people with the disease who live in my own neighborhood," Hurley says. "As both a person with type 1 diabetes and a reporter who has specialized in medical journalism for more than 20 years, I was shocked to learn in the course of researching this book that type 1 appears to be rising just as fast as type 2. I think the media has given so little coverage to the rise of type 1 because it simply doesn't fit with the conventional wisdom that it's supposed to be a super-rare disease caused by a genetic predisposition. Obviously, genes haven't changed, so something in our environment or lifestyle has."
Seeking to explain the mysterious rise in type 1, the book examines five leading scientific hypotheses that offer an explanation:
* The "accelerator hypothesis," which asserts that the rising weight and height of children over the past century has "accelerated" their tendency to develop type 1 by putting the insulin-producing beta cells in their pancreases under stress.
* The "sunshine hypothesis," which holds that the increased time spent indoors is reducing children's exposure to sunlight, which in turn reduces their level of vitamin D (the "sunshine vitamin"). Reduced levels of vitamin D, and reduced exposure to sunshine, have each been linked to an increased risk of type 1 diabetes.
* The "hygiene hypothesis," which holds that lack of exposure to once-prevalent pathogens results in autoimmune hypersensitivity, leading to destruction of the body's insulin-producing beta cells by rogue white blood cells.
* The "cow's milk hypothesis," which holds that exposure to cow's milk in infant formula during the first six months of life wreaks havoc on the immune system and increases the risk to later develop type 1.
* The "POP hypothesis," which holds that exposure to persistent organic pollutants increases the risk of both types of diabetes. "
The book cites recent studies which show that back in 1890, the reported annual death rate from diabetes for children under the age of 15 was 1.3 per 100,000 children in the United States. "Because any death due to diabetes in those days had to be caused by what we now call type 1, researchers consider the 1.3 per 100,000 figure to be a rough estimate of the yearly incidence of new cases at that time," Hurley writes. "In Denmark, the rate was fairly similar, about 2 per 100,000 at the beginning of the 20th century. From that baseline, things took off. By the mid-1980s, the yearly incidence of new cases of type 1 had jumped to 14.8 per 100,000 children in Colorado. By the opening years of the 21st century, the incidence rate in six geographic areas of the United States, as measured in a new study run by the CDC, had climbed to 23.6 per 100,000 among non-Hispanic white children. The rates were 68 percent higher than those reported in Colorado in the 1980s, and more than twice as high as reported in Philadelphia in the 1990s."
The book quotes Dr. Pina Imperatore, chief epidemiologist in the diabetes division at the Centers for Disease Control and Prevention, as noting that it's important to recognize that reported rates in the past are subject to uncertainties. But, she said, "It seems the trend we're seeing in the United States today is similar to what has been reported in Europe and worldwide, about a 3 percent increase annually in the incidence of type 1."
While the CDC is now tracking the incidence of type 1 diabetes in six communities around the country, no national study is tracking rates as they occur elsewhere, Hurley notes. He cites a 2007 editorial in the Journal of the American Medical Association which called for "a coordinated approach for childhood diabetes surveillance (i.e. mandated case-reporting). Only then can society respond effectively to the serious and increasing challenge of diabetes in youth."
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