PCOS Basics: Diagnosis, Insulin Resistance and Treatment Options
Polycystic ovary syndrome affects a substantial proportion of women of reproductive age and is frequently diagnosed on an ultrasound alone, which is not how the diagnosis works. Understanding what it is changes both the treatment and the long-term monitoring.
The name is misleading
The “cysts” seen on ultrasound are not cysts. They are small immature follicles that began to develop and stalled. PCOS is better understood as a disorder of ovulation, androgen excess and, in most cases, insulin resistance, with the ovarian appearance as one feature rather than the cause.
Diagnostic criteria
The widely used Rotterdam criteria require two of three:
- Irregular or absent ovulation. Cycles longer than 35 days, fewer than eight periods a year, or absent periods
- Clinical or biochemical androgen excess. Hirsutism, acne, male-pattern scalp hair thinning, or raised free testosterone
- Polycystic ovarian morphology on ultrasound. Twenty or more follicles per ovary, or increased ovarian volume
Crucially, other causes must be excluded first: thyroid disease, raised prolactin, non-classical congenital adrenal hyperplasia, Cushing’s syndrome and androgen-secreting tumours.
In adolescents, ultrasound should not be used for diagnosis, because multifollicular ovaries are normal in the years after menarche, and irregular cycles are common for the first one to two years.
Insulin resistance as the engine
In the majority of women with PCOS, including many who are lean, insulin sensitivity is reduced. High insulin has two effects that drive the syndrome: it stimulates ovarian theca cells to produce more androgens, and it lowers sex hormone binding globulin in the liver, so more testosterone circulates in the free, active form.
This explains why weight and activity changes improve cycles, and why insulin-sensitising treatment helps a hormonal condition.
Symptoms and features
- Irregular, infrequent or absent periods
- Difficulty conceiving, due to absent ovulation
- Hirsutism on the face, chest, abdomen and back
- Persistent acne beyond adolescence, often along the jawline
- Scalp hair thinning at the crown
- Weight gain and difficulty losing weight, though 20 to 30 percent of women with PCOS are lean
- Acanthosis nigricans, velvety dark skin at the neck, armpits or groin
- Skin tags
- Mood symptoms, with higher rates of depression and anxiety than the general population
- Sleep apnoea, more common than expected for body weight
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Long-term risks worth monitoring
PCOS is a lifelong metabolic condition, not only a fertility issue:
- Type 2 diabetes, at several times background risk
- Gestational diabetes
- Dyslipidaemia and hypertension
- Metabolic fatty liver disease
- Obstructive sleep apnoea
- Endometrial hyperplasia and endometrial cancer, because infrequent ovulation means the uterine lining is exposed to oestrogen without the protective effect of progesterone
- Pregnancy complications including pre-eclampsia and preterm birth
Reasonable monitoring includes an oral glucose tolerance test or HbA1c every one to three years, blood pressure annually, a lipid panel, and evaluation of prolonged amenorrhoea to protect the endometrium.
Treatment by goal
Treatment is chosen according to what the woman wants addressed, not by a single protocol.
Lifestyle, for everyone. Even 5 to 10 percent weight loss, where weight is excess, can restore ovulation. Resistance training and aerobic activity improve insulin sensitivity independent of weight. Reduce refined carbohydrate and sugar-sweetened drinks. No single diet has proved superior; adherence matters more than the pattern. Sleep and stress management have measurable effects on insulin sensitivity.
For irregular cycles and endometrial protection. A combined oral contraceptive pill regulates bleeding, protects the endometrium and reduces androgens. Cyclical progestogen is an alternative for those who cannot take oestrogen. Ignoring very infrequent periods over years is not safe.
For hirsutism and acne. The combined pill is first line. Anti-androgens such as spironolactone are added after about six months if needed, with reliable contraception because of fetal risk. Topical treatments, and mechanical or laser hair reduction, are useful adjuncts. Improvement takes six months or more because of the hair growth cycle.
For fertility. Letrozole is now first-line ovulation induction, ahead of clomiphene. Metformin may be added. Gonadotrophins and IVF follow if needed. Weight loss before conception improves both success rates and pregnancy outcomes.
For metabolic features. Metformin improves insulin sensitivity, modestly assists weight and can regularise cycles. GLP-1 receptor agonists are increasingly used where obesity is a major factor, though they must be stopped before attempting conception.
Inositol has some supportive evidence for cycle regularity and insulin markers and is widely used, though the evidence base is weaker than for metformin.
Practical expectations
PCOS is managed rather than cured, and features change over time. Cycles often become more regular in the late thirties. Androgenic symptoms respond slowly. Metabolic risk persists after menopause, so monitoring should not stop when fertility is no longer the concern.
This is general information. PCOS overlaps with several other conditions and treatment choices depend on your goals, weight, blood results and plans for pregnancy, so they belong with a doctor who knows your case.