🧬 PCOS Insulin Resistance Mechanism Simulator

Insulin Resistance Develops in Muscle and Fat

Muscle and fat cells resist insulin's glucose-uptake signal.

• 65–70%: PCOS prevalence (of women affected)
• Reduced: GLUT4 translocation (impaired glucose uptake)
• 2–3×: Compensatory rise (baseline insulin output)
• Yes: BMI independence (occurs in lean patients)

Post-receptor signaling defect

Insulin signaling breaks down after receptor binding in muscle.

Beta-cell compensation

The pancreas secretes more insulin to compensate for resistance.

Insulin resistance can occur without obesity or high BMI.

Selective tissue resistance

Ovaries stay insulin-sensitive despite systemic tissue resistance.

Hyperinsulinemia — Chronically Elevated Circulating Insulin

Compensatory insulin secretion floods the bloodstream chronically.

• >25 μU/mL: Fasting insulin (vs normal <15)
• 3–5×: Post-meal spike (exaggerated response)
• Suppressed: SHBG level (liver output falls)
• Rises: Free testosterone (less protein-bound)

Chronic hypersecretion

Beta cells secrete insulin continuously, not only after meals.

Hepatic SHBG suppression

High insulin lowers SHBG, freeing more active testosterone.

Low SHBG is a hallmark lab finding in hyperinsulinemic PCOS.

Systemic hormone exposure

Every insulin-sensitive tissue now receives excess hormone signal.

Insulin Directly Stimulates Theca Cell Androgen Synthesis

Insulin binds ovarian receptors and boosts androgen enzymes.

• 2–4×: CYP17A1 activity (rate-limiting enzyme boost)
• Upregulated: StAR protein (cholesterol transport rises)
• Preserved: Theca insulin receptors (unlike peripheral tissue)
• Amplifies: IGF-1 crosstalk (signal via shared pathway)

IRS–PI3K signaling pathway

Insulin activates steroidogenic enzyme transcription directly in theca cells.

CYP17A1 upregulation

Insulin boosts the rate-limiting androgen synthesis enzyme.

This selective ovarian sensitivity is a defining paradox of PCOS.

Insulin–IGF-1 receptor crosstalk

Insulin also signals through IGF-1 receptors on theca cells.

Insulin Amplifies LH-Driven Androgen Production

Insulin and LH together multiply androgen output sharply.

• Increased: LH receptor density (insulin upregulates count)
• Up to 5×: Synergy factor (vs LH alone)
• Elevated: LH pulse frequency (common in PCOS)
• PI3K + PKA: Converging pathways (signal integration)

LH receptor upregulation

Insulin increases theca cell LH receptor numbers over time.

Convergent signaling cascades

Two pathways converge to super-activate androgen synthesis genes.

Insulin and LH together produce far more androgen than either alone.

Amplified pulsatile response

Each LH pulse now triggers a stronger androgen surge.

Hyperandrogenism Drives PCOS Symptoms

Excess ovarian androgens disrupt follicles, skin, and hair.

• ~70%: Hirsutism (of PCOS patients)
• Leading cause: Anovulation (of female infertility)
• 2–3×: Free testosterone (above normal range)
• Common: Acne / alopecia (androgen-driven signs)

Follicular arrest

Excess androgens halt normal ovarian follicle maturation.

Anovulatory cycles

Follicles stall, ovulation fails, cycles turn irregular.

Breaking the insulin-androgen loop can restore regular ovulation.

Peripheral androgen effects

Skin and hair follicles respond visibly to excess androgen.