Vasomotor symptoms and insulin resistance in the study of women's health across the nation.

CONTEXT

Emerging research suggests links between menopausal hot flashes and cardiovascular disease risk. The mechanisms underlying these associations are unclear, due to the incomplete understanding of the physiology of hot flashes. OBJECTIVE AND MAIN OUTCOME MEASURES: We examined the associations between hot flashes/night sweats and glucose and insulin resistance over 8 yr, controlling for cardiovascular risk factors and reproductive hormones.

DESIGN, SETTING, AND PARTICIPANTS: Participants in the Study of Women's Health Across the Nation (SWAN) (n=3075), a longitudinal cohort study, were ages 42-52 yr at entry. Women completed questionnaires (hot flashes, night sweats: none, 1-5 d, ≥6 d, past 2 wk), physical measures (blood pressure, height, weight), and a fasting blood draw [serum glucose, insulin, estradiol (E2), FSH] annually for 8 yr. Hot flashes/night sweats were examined in relation to glucose and the homeostasis model assessment (HOMA) in mixed models, adjusting for demographics, cardiovascular risk factors, medications, and E2/FSH.

RESULTS

Compared to no flashes, hot flashes were associated with a higher HOMAlog index [vs. none; hot flashes, 1-5 d: % difference (95% confidence interval), 2.37 (0.36-4.43), P=0.02; and ≥6 d: 5.91 (3.17-8.72), P<0.0001] in multivariable models that included body mass index. Findings persisted adjusting for E2 or FSH, and were similar for night sweats. Findings were statistically significant, yet modest in magnitude, for the outcome glucose.

CONCLUSIONS

Hot flashes were associated with a higher HOMA index, an estimate of insulin resistance, and to a lesser extent higher glucose. Metabolic factors may be relevant to understanding the link between hot flashes and cardiovascular disease risk.