Results of the study, published recently in the American Journal of Epidemiology, show that those with IGT are nearly twice as likely to die from any cancer and more than four times as likely to die from colon cancer as those with normal glucose tolerance.
"By contrast, adults with outright diabetes had little or no association with risk of cancer death," says senior study author Frederick L. Brancati, M.D., associate professor of medicine and epidemiology at Johns Hopkins.
The exact mechanism underlying the apparent increased risk is not clear, Brancati says, although previous studies suggest that high levels of insulin, which is a biologic growth factor, may promote the development of cancer cells.
IGT, present in about 15 percent of American adults, is defined as blood sugar levels that are higher than normal but not high enough to be classified as diabetes. One-third of people with IGT develop diabetes within five years. Although there are no proven methods for IGT prevention, Brancati says, most people with the condition are overweight and sedentary, so losing weight and increasing physical activity would likely help.
For the study, Brancati and colleagues studied data from 3,054 adults ages
30 to 74 who underwent glucose tolerance testing as part of the Second
National Health and Nutrition Examination Survey (NHANES II) Mortality
Study. This long-term study of adults offered physical exams, laboratory
tests, and questionnaires on health and nutrition-related topics, beginning
in the years 1976 to 1980. Study participants were classified as having
either diagnosed diabetes (247 adults), undiagnosed diabetes (180 adults),
impaired glucose tolerance (477 adults) o
Contact: Karen Blum
Johns Hopkins Medical Institutions