PCOS — the metabolic-reproductive condition and the peptide conversation
10 min read · Uplevel editorial
Your cycles have never been regular. Or they were, and then they weren't. Your skin produces oil faster than you can manage it; there are cysts along your jawline that come back in the same places regardless of what you use. There is hair growing where you don't want it — along the chin, the sideburns, sometimes the abdomen — and hair thinning where you do. Your weight doesn't behave the way effort should predict: you eat carefully, you exercise, and the number on the scale moves reluctantly or not at all, while visceral fat distributes itself around your waist in a pattern that feels metabolic rather than dietary. When you mention any of this in a clinical context, you are sometimes told you have PCOS; sometimes you are told you might; sometimes you are told to lose weight, as though that were the first step rather than a symptom of the same underlying dysregulation that's driving everything else. The diagnosis, when it arrives, often arrives late — sometimes years after the symptoms began, sometimes only when fertility becomes the immediate concern.
The gap between what PCOS actually is and how it tends to be managed in primary care is substantial. The standard response is often the combined oral contraceptive pill, which regularizes cycles and suppresses androgens, plus a suggestion about diet and exercise. Both of those things are reasonable. Neither of them explains what's actually happening, why it's happening, or why the approaches that work for metabolic conditions in the general population often feel insufficient for women with PCOS.
Here is the biology.
PCOS is not primarily an ovarian condition, despite the name. The cysts are a symptom — fluid-filled follicles that developed but didn't complete ovulation — not the cause. The cause, in most presentations, is rooted in the interaction between insulin resistance, androgen excess, and dysregulation of the hypothalamic-pituitary-ovarian axis. These three things are so tightly interwoven in PCOS that it's difficult to say which comes first; in most cases, they are mutually reinforcing, which is why addressing only one of them rarely resolves the condition.
Insulin resistance is present in roughly 70% of women with PCOS, including many who are lean. When insulin is elevated — either because of insulin resistance or because the pancreas is overproducing it — the ovaries' theca cells respond by producing excess androgens, particularly testosterone and androstenedione. The theca cells have LH receptors and insulin receptors, and both insulin and LH drive androgen synthesis in them. So elevated insulin directly amplifies androgen production at the ovarian level, independent of the signaling coming from the hypothalamus and pituitary. Meanwhile, insulin also suppresses sex hormone-binding globulin production in the liver, reducing SHBG levels and leaving more free testosterone biologically active in the bloodstream. More free testosterone means more of the symptoms you're experiencing — the acne, the hirsutism, the hair thinning on the scalp.
At the hypothalamic level, GnRH pulsatility is dysregulated in PCOS. In a normal cycle, GnRH is released in pulses of varying frequency across the cycle, and those pulses govern the ratio of LH to FSH that the pituitary releases. In PCOS, GnRH pulse frequency is elevated — the hypothalamus pulses faster than it should — which drives the pituitary toward producing proportionally more LH than FSH. The elevated LH to FSH ratio is one of the diagnostic markers of PCOS: it stimulates androgen production in the theca cells while failing to provide the adequate FSH signal that follicles need to mature and complete ovulation. Follicles begin to develop, then stall. Multiple small follicles accumulate without ovulating — which is what appears on ultrasound as the polycystic pattern. Ovulation, when it occurs, is infrequent, unpredictable, and sometimes entirely absent. The cycle is irregular or absent. Progesterone — which requires ovulation to be produced in meaningful quantities — stays low throughout the month, which means the progesterone-estrogen balance that the body depends on for mood stability, sleep quality, and uterine health is chronically disrupted.
The phenotypic heterogeneity of PCOS complicates both diagnosis and treatment. The Rotterdam criteria require two of three features: oligo- or anovulation, clinical or biochemical androgen excess, and polycystic ovarian morphology on ultrasound. That means a woman with irregular cycles and elevated androgens but normal-looking ovaries qualifies; a woman with polycystic ovaries and androgen excess but regular cycles qualifies; a woman with anovulation and polycystic ovaries but no clear androgen excess qualifies. These are meaningfully different presentations with somewhat different underlying biology. Lean PCOS — where insulin resistance is present without significant weight excess — is commonly underrecognized because the clinical picture doesn't match the conventional framing that PCOS is a condition of overweight women. Adolescent PCOS is tricky to diagnose because irregular cycles are common in the first years after menarche. Post-reproductive PCOS leaves a metabolic and cardiovascular risk legacy even after fertility is no longer a concern: the insulin resistance and androgen-driven risk factors don't disappear at menopause.
Conventional management has several established pillars. Combined oral contraceptives suppress LH-driven androgen production, increase SHBG (reducing free testosterone), and impose cycle regularity — a meaningful quality-of-life intervention for women managing androgen-related symptoms and irregular cycles when fertility isn't the current goal. Metformin addresses insulin sensitivity at the hepatic level; it reduces hepatic glucose output and improves peripheral insulin signaling, lowering fasting insulin and the downstream androgen production it drives. Spironolactone is an androgen receptor blocker frequently used for hirsutism and acne when the cosmetic burden is significant. For ovulation induction, letrozole — an aromatase inhibitor — has largely replaced clomiphene as first-line; it works by blocking the estrogen signal to the hypothalamus, prompting a compensatory FSH surge that stimulates follicular development. Inositol, particularly myo-inositol and d-chiro-inositol in a 40:1 ratio, has enough evidence in the literature to be considered a reasonable adjunct for insulin sensitivity and ovarian function, though the evidence quality is not uniform.
The peptide conversation in PCOS sits primarily at the intersection of insulin sensitivity and metabolic regulation. GLP-1 receptor agonists — semaglutide and tirzepatide, both of which are now being used in clinical practice at microdose or standard dosing for metabolic health — have emerged as a meaningful tool for the insulin resistance component of PCOS. These compounds increase insulin secretion in response to glucose, suppress glucagon, slow gastric emptying, and reduce appetite via central mechanisms. For women with PCOS where insulin resistance is the dominant driver — the metabolic phenotype — GLP-1 agonist therapy may support significant improvements in insulin sensitivity, androgen levels (which decline as insulin falls), menstrual regularity, and metabolic markers. Tirzepatide adds GIP agonism to GLP-1 agonism, producing additive effects on insulin secretion and metabolic function. Research is ongoing on the role of dual agonism specifically in PCOS populations, and early data is encouraging. Mazdutide, a GLP-1/glucagon dual agonist under investigation, has been researched for metabolic and obesity-related outcomes, including in PCOS-adjacent populations, though it is not yet approved and remains an area of active research rather than established practice.
MOTS-c is a mitochondrial-derived peptide — encoded in the mitochondrial genome rather than the nuclear genome, which makes it structurally unusual. It has been researched for its role in cellular insulin signaling, specifically its ability to translocate to the nucleus under conditions of metabolic stress and regulate AMPK-related pathways. AMPK activation improves glucose uptake and mitochondrial function and is part of how metformin works; MOTS-c appears to engage overlapping mechanisms. Research in animal models and early human studies suggests MOTS-c may enhance insulin sensitivity at the cellular level, which is directly relevant to the metabolic component of PCOS. The clinical evidence base is at an earlier stage than for GLP-1 agonists, and this belongs in a conversation with a prescribing provider rather than a self-directed intervention.
Kisspeptin-10 research is worth noting in the context of PCOS given its central role in the HPO axis. Kisspeptin — the same molecule that the KNDy neurons in the hypothalamus co-express — is one of the critical upstream regulators of GnRH pulsatility. GnRH neurons have kisspeptin receptors; kisspeptin activates them. In PCOS, the kisspeptin-GnRH-LH pathway is implicated in the elevated GnRH pulse frequency that drives the skewed LH/FSH ratio. Kisspeptin-10 has been studied in research settings for its capacity to modulate GnRH pulsatility and gonadotropin secretion; some research has explored whether kisspeptin signaling could be used to recalibrate the HPO axis dysregulation characteristic of PCOS. This remains research-stage work — kisspeptin-10 is not an approved treatment for PCOS — but it represents a mechanistically interesting direction given the central role of GnRH pulsatility in the condition.
The foundational interventions in PCOS are not exotic. Insulin sensitivity responds to diet — specifically, dietary patterns that reduce glycemic load and support AMPK signaling, including lower-refined-carbohydrate approaches, resistance training, and sleep optimization, because sleep deprivation acutely worsens insulin resistance. The evidence for exercise in PCOS is strong and underutilized; both aerobic and resistance training improve insulin sensitivity and have been shown to support ovulatory function in some studies. Weight management — where relevant — matters, but the framing that weight loss is simply about willpower ignores that the insulin-driven fat storage in PCOS is a physiological process, and that addressing the underlying insulin dysregulation often makes weight management more tractable rather than requiring greater restriction. Lean PCOS requires particular attention here because the metabolic interventions are the same even when body weight is not the visible symptom.
PCOS is a lifelong condition that changes in expression across reproductive life stages. The adolescent presentation may be dominated by cycle irregularity and acne; the reproductive-age presentation by fertility, metabolic, and androgenic concerns; the perimenopausal and postmenopausal presentation by cardiovascular and metabolic risk. Getting a comprehensive evaluation — from a reproductive endocrinologist, a gynecologist with specific PCOS expertise, or both — matters not just for managing the immediate presenting symptoms but for understanding the full picture of what this condition does across time. Hormone levels should be interpreted in context — LH, FSH, total and free testosterone, SHBG, DHEA-S, insulin, fasting glucose, and a full lipid panel are all part of understanding a PCOS presentation. Ultrasound findings alone are neither necessary nor sufficient. The evaluation should be thorough, and the treatment plan should address the metabolic and reproductive dimensions simultaneously, not one at the expense of the other.
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