The relationship of menstrual irregularity to type 2 diabetes in Pima Indian women.

OBJECTIVE: Menstrual irregularity is associated with hyperinsulinemia and hyperandrogenemia in nondiabetic Pima Indian women of childbearing age. In this population-based study, we determined the relationship of menstrual irregularity to type 2 diabetes in Pima Indian women. RESEARCH DESIGN AND METHODS: Participants for this cross-sectional analysis were 695 nonpregnant Pima Indian women, aged 18-44 years, involved in an ongoing epidemiologic study of diabetes among residents of the Gila River Indian Community of Arizona. Clinical data were collected by questionnaire and an examination that included a 75-g oral glucose tolerance test; diabetes was diagnosed by World Health Organization criteria. Menstrual irregularity was defined as an interval of 3 months or more between menses, when not pregnant, since age 18 years. RESULTS: History of menstrual irregularity was significantly associated with a high prevalence of diabetes (37 vs. 13%; odds ratio = 4.2, 95% CI = 1.6-10.8) in the least obese women (BMI < 30 kg/m2), adjusted for the effects of age and overall obesity. This association was, in part, because of greater central obesity in women with irregular menses. In more obese women, there was little association with menstrual irregularity, and diabetes was frequent regardless of menstrual history. CONCLUSIONS: Prevalence of type 2 diabetes is higher among Pima Indian women with a history of menstrual irregularity. The difference is most pronounced among the least obese group of women. This association may be because of insulin resistance and hyperinsulinemia, which predict type 2 diabetes, also causing hyperandrogenism and menstrual irregularity. The findings reinforce the need to evaluate women with menstrual irregularity for hyperglycemia.