Jan. 6, 2003 -- Despite the negative news about hormone replacement therapy (HRT) in recent months, new research suggests that HRT may provide a significant benefit in helping some women reduce their risk of diabetes. But even the study researchers say it's still too early to make any recommendations about using HRT as a tool to prevent type 2 diabetes.
The study, published in the Jan. 7 issue of Annals of Internal Medicine, found that postmenopausal women with heart disease who took a combination of estrogen and progestin (Prempro) had a 35% lower risk of developing diabetes than those who took a placebo. The women on HRT also had more normal fasting blood sugar levels, which when high suggest the likely onset of diabetes. Wyeth-Ayerst, the manufacturer of Prempro, sponsored the study.
Researchers say it's the first such benefit found in a large number of women -- based on more than 2,700 postmenopausal women with heart disease who were followed for about four years. But other results from this same study, as well as another major study known as the Women's Health Initiative (WHI) published in July 2002, show that postmenopausal women on HRT -- combination estrogen and progestin -- face a higher risk of heart disease and breast cancer.
That's why experts, including Eugene Barrett, MD, president-elect of the American Diabetes Association, say this study doesn't provide a reason to change recommendations for HRT, considering increased heart disease risks found by the same study.
Barrett says that until now there really hasn't been much information on the role of HRT in the development of diabetes, and this study raises some interesting questions.
"It gives us a clue that there is something about the biology of estrogen that influences diabetes," says Barrett. But he says that's a matter for clinical research and shouldn't be a factor for most women considering HRT.
Study researcher Alka M. Kanaya, MD, assistant professor of medicine at the University of California, San Francisco, says it's also hard to know whether these findings would apply to other postmenopausal women without heart disease, and that issue will be looked at in larger clinical trials.
"These findings are scientifically interesting, but they need confirmation by further studies," says Kanaya. "It is premature to recommend the use of hormone replacement therapy for the prevention of diabetes."
Karen E. Friday, MD, associate professor of medicine at Tulane University, agrees that further studies are needed and says her great hope is that the negative press about HRT in recent months has not halted research on estrogens because there is more that we need to know.
According to Friday, both animal and human studies suggest that estrogen plays a significant role in how the body regulates the sugar glucose, and she says we don't yet understand all of the potential mechanisms and influences of various forms of estrogen on diabetes.
Since diabetes is known to greatly increase a person's risk of heart disease, finding a way to safely reduce that additional risk through the use of HRT could have tremendous potential.
"For example, if you're a postmenopausal woman that hasn't developed heart disease, preventing diabetes -- in theory -- might help you prevent future heart disease," says Friday. "But if you're a diabetic woman who's already faces an increased risk of heart disease, does taking estrogen now make that better or worse? That question remains to be answered."
SOURCE: Annals of Internal Medicine, Jan. 7, 2003 • Alka M. Kanaya, MD, assistant professor of medicine, University of California, San Francisco • Eugene Barrett, MD, president-elect, American Diabetes Association • Karen E. Friday, MD, associate professor of medicine, Tulane University • WebMD Feature: "Conflicting Studies Muddy HRT Waters."