Polycystic Ovaries and Insulin Resistance

Polycystic ovaries and insulin resistance are closely linked, with insulin resistance affecting the majority of women with PCOS and playing a central role in driving its hormonal and metabolic features. Excess insulin stimulates the ovaries to overproduce androgens, disrupting ovulation and contributing to irregular periods, acne, hirsutism and weight gain. Understanding this connection is essential for effective management, as addressing insulin resistance can improve both reproductive and long-term metabolic health. This article explains the causes, symptoms, diagnosis and treatment options available, including NHS-supported lifestyle and pharmacological approaches.

How are polycystic ovaries and insulin resistance linked?

Insulin resistance causes hyperinsulinaemia, which directly stimulates ovarian androgen production and suppresses SHBG, disrupting ovulation and driving the core features of PCOS in a bidirectional relationship.

Polycystic ovary syndrome (PCOS) and insulin resistance are closely intertwined. Research suggests that insulin resistance affects between 65 and 80 per cent of women with PCOS, regardless of body weight, though this figure varies across studies and populations.^[19][20] Insulin is a hormone produced by the pancreas that allows cells to absorb glucose from the bloodstream. When cells become resistant to insulin's signal, the pancreas compensates by producing more insulin, leading to elevated circulating insulin levels (hyperinsulinaemia).

This excess insulin directly stimulates the ovaries to produce higher amounts of androgens, particularly testosterone, and also suppresses sex hormone-binding globulin (SHBG), increasing the proportion of free androgens in the circulation.^[16][17] Elevated androgens disrupt the normal development of ovarian follicles, preventing regular ovulation and contributing to the hallmark features of PCOS, including irregular periods and the appearance of multiple small follicles on ultrasound. It is worth noting that ultrasound findings alone are not sufficient to diagnose PCOS; diagnosis requires assessment against established criteria (such as the Rotterdam criteria), which include menstrual irregularity and evidence of androgen excess alongside ultrasound appearances.^[15] The relationship between PCOS and insulin resistance is bidirectional: PCOS itself can worsen insulin resistance through hormonal imbalances and, in some cases, through associated weight gain.

Insulin resistance in PCOS is not simply a consequence of excess body weight. Lean women with PCOS can also experience significant insulin resistance, suggesting an intrinsic metabolic defect that is partly independent of adiposity.^[21][22] Understanding this link is central to managing PCOS effectively, as treatments targeting insulin resistance can improve both metabolic and reproductive outcomes.

Bolt Pharmacy is a GPhC-registered UK online pharmacy offering online weight-management consultations, with prescriber review and pharmacist support, which may be relevant for women with PCOS exploring broader metabolic care alongside their NHS treatment.

What symptoms suggest insulin resistance with PCOS?

Key symptoms include irregular periods, acanthosis nigricans, central weight gain, persistent fatigue, sugar cravings and hirsutism, though no single symptom confirms insulin resistance without testing.

Several symptoms may indicate that insulin resistance is present alongside PCOS, though no single symptom is diagnostic on its own. Women should be aware of the following signs that may prompt further investigation:

• Irregular or absent periods, which can reflect disrupted ovulation driven by elevated insulin and androgens

• Unexplained weight gain, particularly around the abdomen, which is associated with insulin resistance

• Acanthosis nigricans, a darkening and thickening of the skin in skin folds such as the neck, armpits or groin, which is a recognised marker of hyperinsulinaemia^[24]

• Persistent fatigue or energy dips, especially after carbohydrate-rich meals

• Increased hunger or sugar cravings, reflecting impaired glucose regulation

• Acne and excess facial or body hair (hirsutism), driven by androgen excess that insulin resistance amplifies

• Difficulty losing weight despite dietary changes and physical activity

Many of these symptoms overlap with other conditions, and their presence does not confirm insulin resistance without appropriate testing. Some women with PCOS and significant insulin resistance may have few or no obvious symptoms, which is why clinical guidelines, including NICE guidance on PCOS and NHS recommendations, advise proactive metabolic screening for women with the condition.^[5][6]

Women who notice a combination of these features, particularly irregular cycles alongside skin changes or central weight gain, should discuss them with their GP. If periods have been absent for three months or more, or if there is heavy, prolonged or unexpected bleeding, it is important to seek GP review promptly, as these may require assessment and, where appropriate, endometrial protection. Early identification of insulin resistance allows for timely intervention, which can meaningfully reduce the risk of longer-term metabolic complications.

How is insulin resistance diagnosed in women with PCOS?

There is no single agreed UK test; clinicians use fasting glucose, HbA1c, and where indicated an oral glucose tolerance test, alongside clinical assessment of waist circumference and blood pressure.

There is currently no single universally agreed test for diagnosing insulin resistance in clinical practice in the UK. NICE guidance on PCOS (the current NICE guideline on polycystic ovary syndrome: diagnosis and management) does not mandate a specific insulin resistance test as part of routine assessment. Instead, clinicians use a combination of blood tests and clinical assessment to evaluate metabolic risk in women with PCOS.

Commonly used investigations include:

• Fasting glucose and HbA1c: to screen for impaired fasting glucose or type 2 diabetes

• Fasting insulin levels: elevated fasting insulin alongside normal or raised glucose can suggest insulin resistance, though this test is not standardised across NHS laboratories and is not routinely recommended in primary care

• HOMA-IR (Homeostatic Model Assessment of Insulin Resistance): calculated from fasting glucose and insulin, this is used in research settings and some specialist clinics; it is not routinely available on the NHS and is not recommended as a standard diagnostic tool in primary care

• Oral glucose tolerance test (OGTT): recommended by NICE for women with PCOS who have a BMI above 25 kg/m2, or other risk factors for type 2 diabetes; women from certain ethnic groups (including South Asian, Black African and Black Caribbean backgrounds) may warrant consideration at lower BMI thresholds, in line with broader NHS diabetes screening guidance^[4][13]

• Lipid profile: dyslipidaemia (raised triglycerides, low HDL cholesterol) is commonly associated with insulin resistance

A GP or specialist may also assess waist circumference and blood pressure as part of a broader cardiometabolic risk assessment. Women with PCOS should ideally have these metabolic markers reviewed at diagnosis and periodically thereafter, even in the absence of symptoms, given the elevated background risk. Referral to an endocrinologist or specialist PCOS clinic may be appropriate where results are complex or inconclusive.

Treatment options available through the NHS for PCOS and insulin resistance

Metformin is the main NHS pharmacological option for insulin resistance in PCOS, recommended off-label by NICE alongside lifestyle intervention and, where relevant, combined oral contraceptives for symptom management.

NHS treatment for PCOS-related insulin resistance is guided by NICE guidance on polycystic ovary syndrome and focuses on managing symptoms and reducing long-term metabolic risk. Treatment is tailored to the individual's priorities, which may include cycle regulation, fertility, androgen-related symptoms or metabolic health.

Metformin is the most widely used pharmacological treatment for insulin resistance in PCOS on the NHS. It is not licensed specifically for PCOS (its use in this context is off-label), but NICE recommends it as an option for women with PCOS who have a BMI above 25 kg/m2, or where lifestyle measures have not been sufficient, following a shared decision-making discussion.^[4][13] Metformin works by reducing hepatic glucose production and improving peripheral insulin sensitivity. Common side effects include nausea, diarrhoea and abdominal discomfort, which are often reduced by taking it with food or using a slow-release formulation.

Important safety considerations for metformin include: kidney function (eGFR) should be checked before starting and monitored periodically, as metformin is not recommended when eGFR falls below 30 ml/min/1.73 m2 and should be used with caution at lower eGFR levels; long-term use is associated with a risk of vitamin B12 deficiency, so periodic monitoring is advisable; during illness, dehydration or before procedures involving contrast media, metformin should be temporarily stopped (sick-day guidance); women planning pregnancy or who are pregnant should discuss metformin use with their doctor, as its use in pregnancy requires specialist review.^[10][31]

Combined oral contraceptive pills (COCPs) are frequently prescribed to regulate menstrual cycles and manage androgen-related symptoms such as acne and hirsutism. They do not directly address insulin resistance. Evidence on their effect on insulin sensitivity is mixed and effect sizes are generally small; the overall risk-benefit balance, including VTE and cardiometabolic considerations, should be assessed individually with a clinician.

For women with PCOS who are overweight and have not responded to lifestyle changes alone, referral to a structured NHS weight management programme may be offered. In some cases, where a woman meets the criteria set by her local Integrated Care Board (ICB), access to pharmacological weight management support may be considered, though commissioning decisions vary across England.

Women should discuss their individual priorities with their GP or gynaecologist to agree a management plan that addresses both reproductive and metabolic aspects of PCOS.

Can lifestyle changes really improve insulin resistance with PCOS?

Yes; even 5 to 10 per cent weight loss in overweight women improves insulin sensitivity, restores ovulation and reduces androgen levels, with low-GI diet and regular exercise both showing benefit.

Lifestyle changes are genuinely effective at improving insulin resistance in women with PCOS, and they are recommended as the first-line intervention by NICE guidance on PCOS. Even modest weight loss of 5 to 10 per cent of body weight in women who are overweight has been shown in clinical studies and systematic reviews to improve insulin sensitivity, restore more regular ovulation, reduce androgen levels and improve the overall symptom burden of PCOS.

Dietary approaches that have evidence in PCOS include:

• Low glycaemic index (low-GI) diets, which reduce postprandial glucose and insulin spikes

• Reduced refined carbohydrate intake, replacing white bread, sugary drinks and processed foods with wholegrains, legumes and vegetables

• Mediterranean-style eating patterns, which have been associated with improved insulin sensitivity in women with PCOS

No single diet has been proven superior for all women with PCOS, and the most effective approach is one that is sustainable for the individual.

Physical activity improves insulin sensitivity independently of weight loss. Both aerobic exercise (such as brisk walking, cycling or swimming) and resistance training have demonstrated benefit. UK Chief Medical Officers' Physical Activity Guidelines recommend at least 150 minutes of moderate-intensity activity per week for adults, and this target is relevant and achievable for most women with PCOS.^[11][12]

Sleep quality and stress management are increasingly recognised as relevant factors, as poor sleep and chronic psychological stress can worsen insulin resistance through cortisol-mediated pathways. Women with PCOS have higher rates of anxiety and depression, and addressing mental wellbeing is an integral part of holistic management.^[29][30]

Lifestyle changes are not a quick fix, but consistent, sustainable habits can produce meaningful and lasting improvements in insulin resistance and PCOS symptoms.

What are the long-term health risks if insulin resistance goes untreated?

Untreated insulin resistance in PCOS substantially raises the risk of type 2 diabetes, cardiovascular disease, MASLD, endometrial cancer and pregnancy complications, making proactive monitoring and management essential.

Untreated insulin resistance in women with PCOS significantly increases the risk of several serious long-term health conditions, making proactive management important even when immediate symptoms are mild. Women with PCOS have a substantially higher lifetime risk of developing type 2 diabetes compared with women without the condition, and this risk is amplified when insulin resistance is present and unaddressed.

Key long-term risks include:

• Type 2 diabetes: impaired glucose tolerance can progress to type 2 diabetes, particularly without lifestyle intervention or appropriate treatment

• Cardiovascular disease: insulin resistance is associated with dyslipidaemia, hypertension and chronic low-grade inflammation, all of which contribute to increased cardiovascular risk

• Metabolic dysfunction-associated steatotic liver disease (MASLD), previously termed non-alcoholic fatty liver disease (NAFLD): this condition is more prevalent in women with PCOS and insulin resistance

• Endometrial cancer: chronic anovulation leads to unopposed oestrogen stimulation of the uterine lining, increasing the risk of endometrial hyperplasia and cancer over time.^[25][26] Women who have not had a period for three months or more, or who experience heavy, prolonged or unexpected bleeding, should seek GP review, as endometrial protection may be needed

• Obstructive sleep apnoea: more common in women with PCOS, particularly those with central adiposity related to insulin resistance

• Pregnancy-related complications: women with PCOS and insulin resistance have an increased risk of gestational diabetes and hypertensive disorders of pregnancy; preconception review with a GP or specialist is advisable, including discussion of weight optimisation, folic acid supplementation and diabetes screening^[28]

Regular monitoring is therefore important. NICE recommends that women with PCOS have periodic assessment of blood pressure, fasting glucose or HbA1c, and lipid profile, starting at diagnosis and reviewed at regular intervals thereafter.^[5][6] Women should contact their GP if they notice new symptoms such as increased thirst, frequent urination or unexplained fatigue, which may indicate worsening glucose regulation.

Any suspected adverse effects from treatments used in managing PCOS and insulin resistance can be reported to the MHRA via the Yellow Card scheme at yellowcard.mhra.gov.uk. Early and sustained management of insulin resistance remains the most effective strategy for reducing these long-term risks.

Scientific References

1. Polycystic ovary syndrome: metformin in women not planning pregnancy (ESUOM6) – what is PCOS.
2. Polycystic ovary syndrome: metformin in women not planning pregnancy (ESUOM6) – about metformin.
3. Polycystic ovary syndrome: metformin in women not planning pregnancy (ESUOM6) – full PDF.
4. Polycystic ovary syndrome (PCOS): assessment and management – adaptation report 4 (GID-NG10436).
5. NICE recommends annual review for PMOS in new draft guideline aimed at improving diagnosis and care.
6. Polyendocrine metabolic ovarian syndrome: assessment and management (GID-NG10436).
7. Polycystic ovary syndrome | Treatment summaries – BNF.
8. Metformin hydrochloride | Drugs – BNF.
9. Use of metformin to treat diabetes now expanded to patients with moderately reduced kidney function.
10. Metformin and reduced vitamin B12 levels: new advice for monitoring patients at risk.
11. Physical activity guidelines: UK Chief Medical Officers' report.
12. Physical activity guidelines for adults aged 19 to 64 – NHS.
13. Diabetes in pregnancy: management from preconception to the postnatal period (NG3).
14. Appendix A1: Summary of evidence from surveillance (NG246) – BMI cut-off points for South Asian and Chinese populations.
15. Revised 2003 consensus on diagnostic criteria and long-term health risks related to polycystic ovary syndrome (Rotterdam criteria). Fertil Steril. 2004..
16. Decoding androgen excess in polycystic ovary syndrome: Roles of insulin resistance and other key intraovarian and systemic factors. World J Diabetes. 2025..
17. Obesity, insulin, sex steroids and ovulation. Int J Obes Relat Metab Disord. 2000..
18. Polycystic Ovary Syndrome-Associated Acne: The Interplay of Hyperandrogenism, Insulin Resistance, and Therapeutic Strategies. Cureus. 2025..
19. Polycystic ovary syndrome with metabolic syndrome and diabetes: a systematic review and meta-analysis. J Ovarian Res. 2025..
20. Comparison of Clinical, Metabolic, and Hormonal Profiles in Obese Versus Lean Women With Polycystic Ovary Syndrome: A Systematic Review and Meta-Analysis. Endocrinol Diabetes Metab. 2025..
21. Relationship among obesity, insulin resistance, and hyperinsulinemia in the polycystic ovary syndrome. Endocrine. 2019..
22. Metabolic effects of polycystic ovary syndrome in adolescents. Ann Pediatr Endocrinol Metab. 2015..
23. Diverse impacts of aging on insulin resistance in lean and obese women with polycystic ovary syndrome: evidence from 1345 women with the syndrome. Eur J Endocrinol. 2014..
24. Is Acanthosis Nigricans a Marker for Metabolic Syndrome? A Systematic Review. Am J Clin Dermatol. 2025..
25. Screening for endometrial hyperplasia and endometrial cancer in premenopausal women with PCOS. BMJ Open. 2025..
26. Cancer risk and PCOS. Steroids. 2013..
27. Polycystic ovary syndrome and endometrial cancer. Semin Reprod Med. 2008..
28. The impact of hyperandrogenemia on pregnancy complications and outcomes in patients with PCOS: a systematic review and meta-analysis. Hypertens Pregnancy. 2024..
29. Depression and anxiety among women with polycystic ovarian syndrome in low- and middle-income countries: a systematic review and meta-analysis. Front Glob Womens Health. 2025..
30. Yoga as a complementary intervention for polycystic ovary syndrome management: a systematic review. Front Reprod Health. 2025..
31. Vitamin B12 and long-term metformin use: a scoping review. BMJ Open. 2025..

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