Aims: In a large ethnically diverse nationwide sample of post-menopausal women we explored the relationship between fasting insulin levels, ethnicity, and a wide range of anthropometric, socio-economic, and lifestyle factors.
Methods: Subjects were post-menopausal women aged 50-79 years without diagnosed diabetes mellitus comprising a subsample (n = 3500) of the Women's Health Initiative (WHI) Clinical Trial and Observational Study. In a cross-sectional survey at baseline, we analysed the association between ethnicity and fasting insulin using analysis of covariance procedures and identified independent correlates of hyperinsulinaemia, defined by the 75th percentile cut point for each ethnic group.
Results: Fasting insulin levels were higher among African-American and Hispanic women than among non-Hispanic White or Asian women. These differences persisted after adjustment for age, educational attainment, total and central body obesity, adult weight change, family history of diabetes, smoking status, alcohol consumption, use of menopausal hormone therapy and physical activity. Higher levels of body mass index, waist-hip ratio, adult weight gain, and lower levels of total and moderate or strenuous recreational activity were independent correlates of fasting hyperinsulinaemia. Habitual walking was also inversely associated with fasting insulin.
Conclusions: In this cross-sectional analysis, fasting insulin levels were higher among African-American and Hispanic post-menopausal women as compared with non-Hispanic White and Asian women. In addition, obesity, adult weight gain, and low levels of moderate or strenuous physical activity were independently associated with hyperinsulinaemia.