Association of follicle-stimulating hormone levels and risk of type 2 diabetes in older postmenopausal women.

OBJECTIVE: Recent studies of perimenopausal women have observed associations of follicle-stimulating hormone (FSH) levels with markers of insulin resistance, independent of estradiol. Whether FSH is related to type 2 diabetes (T2D) in older women who have completed the menopause transition remains unknown. We assessed the association of FSH levels with diabetes and measures of insulin resistance among 588 postmenopausal Finnish women.

METHODS: Study participants were aged 53 to 73 years and not using hormone therapy at baseline (1998-2001) when FSH was measured. Prevalence of T2D was assessed at baseline, along with fasting insulin and glucose levels. Incident T2D, and insulin and glucose levels were assessed 7 to 9 years later at follow-up examination.

RESULTS: After adjustment for age, estradiol, body mass index, smoking, lipids levels, and other factors, women with higher FSH (>50 IU/L) had a lower prevalence of T2D (odds ratio 0.49, 95% confidence interval [CI] 0.28-0.86) than women with lower FSH. Each 1 unit increase in FSH level was associated with a significant 1.9% lower risk of T2D (95% CI 0.966-0.997, P = 0.02). Higher FSH was associated with marginally significant lower incidence of T2D at follow-up (hazard ratio 0.53, 95% CI 0.27-1.02). Baseline FSH levels were inversely correlated with fasting insulin and glucose levels at both baseline and follow-up visits (all P < 0.05). After adjustment, FSH was modestly associated with fasting insulin at baseline (P = 0.01) and at follow-up (P = 0.11).

CONCLUSIONS: Higher postmenopausal FSH levels were associated with lower prevalent and incident T2D and fasting insulin levels. These findings warrant replication in larger prospective studies.