Menstrual cycles and diabetes

[Shauna]

Study Links Long Menstrual Cycle to Diabetes Risk

By Suzanne Rostler

NEW YORK (Reuters Health) - Young women who have long or irregular menstrual cycles may have a higher risk of developing type 2 diabetes by middle age, study findings suggest.

According to the results, women whose menstrual cycles were at least 40 days long were twice as likely to be diagnosed with diabetes, compared with women whose cycles lasted 26 to 31 days, regardless of body weight. However, the risk was even greater for obese women, researchers report in the November 21st issue of The Journal of the American Medical Association (news - web sites).

Similarly, women with menstrual cycles that were too irregular to estimate were about twice as likely to develop diabetes, compared with women whose cycles were more predictable.

It is not clear why long and irregular cycles may raise a woman's risk of developing type 2 diabetes, a disease in which the body no longer responds to insulin, the body's key blood sugar-regulating hormone. But the researchers, led by Dr. Caren G. Solomon of Brigham and Women's Hospital in Boston, Massachusetts, note that previous studies have found an association between long and irregular cycles and insulin resistance, and suggest that these types of cycles reflect an underlying metabolic abnormality.

In an interview with Reuters Health, Solomon said she suspects that many women with irregular menstrual cycles may have undiagnosed polycystic ovary syndrome (PCOS), a disorder marked by excessive levels of male hormones. Many women with PCOS are also resistant to insulin, she added.

``The most reasonable explanation may be that many women may actually have (undiagnosed) PCOS and that group is insulin-resistant,'' Solomon said.

The study included more than 101,000 women aged 18 to 22 with no history of diabetes. They were interviewed every 2 years for the next 18 years about their weight, exercise habits, smoking status and other lifestyle factors. During that time, 507 cases of type 2 diabetes were diagnosed among the women.

Women with long and irregular cycles were more likely to be overweight at the beginning of the study and to gain more weight over the next 18 years. Women with long and short cycles lasting less than 21 days were more likely than women with normal cycles to report severe teenage acne, abnormal hair growth, ovulatory infertility and gestational diabetes.

``These findings are consistent with the suggestion...that menstrual cycle irregularities may be a marker for associated metabolic abnormalities and suggest that women with this history might particularly benefit from lifestyle approaches to reduce risk, such as weight control and exercise,'' the study authors conclude.

Solomon added that women should tell their doctors if their menstrual cycles are long or irregular, but stressed that not every woman whose cycle does not conform to the 26-to-31-day norm needs to be screened for diabetes.

SOURCE: The Journal of the American Medical Association 2001;286:2421-