Are higher circulating androgens in women associated with increased insulin resistance even outside PCOS?

Evidence from large-scale longitudinal and cross-sectional studies indicates that the relationship between hyperandrogenism and metabolic dysfunction in women is not exclusive to Polycystic Ovary Syndrome (PCOS). Higher levels of circulating androgens are consistently associated with markers of insulin resistance across various life stages, including the menopausal transition.

Clinical and effectiveness evidence

Large population studies demonstrate a robust link between androgen profiles and insulin sensitivity in women without PCOS:

• SWAN Study Findings: The Study of Women’s Health Across the Nation (SWAN), involving over 3,000 midlife women, found that a higher Free Androgen Index (FAI) is significantly correlated with increased HOMA-IR (Homeostatic Model Assessment for Insulin Resistance) scores. This association remains significant even after adjusting for body mass index (BMI), suggesting that androgens influence metabolism independently of total body fat.
• Bioavailability Matters: Research highlights that low levels of Sex Hormone-Binding Globulin (SHBG) are a potent predictor of insulin resistance. Because SHBG binds testosterone, lower levels increase the fraction of "free" or bioactive testosterone, which correlates more strongly with metabolic risk than total testosterone levels.
• Postmenopausal Context: In postmenopausal women—where PCOS is no longer typically diagnosed—elevated free testosterone levels remain associated with a higher risk of developing type 2 diabetes (Hazard Ratio ~1.4 to 1.5 for the highest quartiles in several cohorts).

Mechanistic explanations

The link between high androgens and insulin resistance is driven by tissue-specific molecular disruptions:

• Skeletal Muscle Interference: Elevated androgens can impair the translocation of GLUT4 (the primary insulin-regulated glucose transporter) to the cell membrane in female skeletal muscle, directly reducing the rate of glucose uptake.
• Adipose Tissue Dysfunction: Androgens promote a "pro-inflammatory" state in adipose tissue. This leads to increased secretion of cytokines like TNF-alpha and IL-6 and decreased production of adiponectin (an insulin-sensitizing hormone), which collectively interfere with insulin receptor substrate (IRS) signaling.
• The Vicious Cycle: A bidirectional relationship exists where hyperinsulinemia (resulting from resistance) further stimulates androgen production in the ovaries and adrenals while suppressing liver production of SHBG, creating a self-reinforcing loop of hormonal and metabolic imbalance.

Bottom line

Higher circulating free testosterone is a significant risk factor for insulin resistance in women, regardless of a PCOS diagnosis. This association is driven by androgen-induced impairment of glucose transport and adipose tissue inflammation, emphasizing the importance of monitoring androgen levels as a marker for metabolic health in midlife women.