“Over an eight-year follow-up, the risk was twice as high, even after we adjusted for body mass and other factors,” stated Solomon. However she says women with such menstrual abnormalities needn’t panic because the risk can be reduced markedly by lifestyle measures, most notably regular exercise and weight control.

Menstrual cycles 40 days or longer or irregular cycles appear to be markers for some sort of underlying metabolic abnormality, Solomon says. For example, previous reports have linked an increased risk of diabetes to a condition called polycystic ovary syndrome, in which the body makes too much of the male hormone testosterone that can affect the menstrual cycle.

The study is the first to specifically link menstrual cycles and Type II diabetes, the kind that arises in adult life and is non-insulin dependent, Solomon says. The increased risk of Type II diabetes found in the study arises from resistance to insulin activity, she says. In Type II diabetes the body still makes insulin, but doesn’t use it efficiently. In Type I diabetes, the body doesn’t make insulin, and sufferers must have injections of the hormone to keep their blood sugar levels on an even keel.

The report uses data from the Nurses Health Study II, which followed more than 100,000 women starting in 1989. The women supplied information about their menstrual cycles and other personal data — weight, height, family history of diabetes, the level of physical activity.

In 1997 that study found a doubled risk of diabetes in women with the menstrual abnormalities, compared with women with normal menstrual cycles that ranged from 26 to 31 days. The risk was highest for obese women.

The results of the study are not surprising but are valuable because they provide “another piece in the puzzle of trying to tease out what are the risk factors for Type II diabetes,” says Dr. Nathaniel G. Clark, national vice president for clinical affairs of the American Diabetes Association.

Obesity has long been identified as a risk factor, Clark says. “What this study shows is that if you have irregular periods, you are at increased risk whether or not you are obese. Each is an independent risk factor,” he says.

What To Do

Solomon says, “The study points to the fact that having these unusual cycles can be a marker that there are other metabolic  irregularities going on, so a woman should inform her medical caregiver about them. A woman should at least be going over it with a physician. And we know that when individuals engage in regular physical activity and control their weight, the risk of diabetes is lowered.”

Sources: Journal of the American Medical Association

The American Diabetes Association

Centers for Disease Control and Prevention.

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