Short answer: Insulin resistance can make hirsutism worse. When the body responds poorly to insulin, it makes more of it, and high insulin pushes the ovaries to produce more androgens and lowers SHBG, the protein that keeps testosterone inactive.[1] It affects about half of people with PMOS.[2] Improving insulin resistance helps your overall health, but its effect on hair is small: In a Cochrane review, lifestyle changes lowered hair scores by only about 1 point on a 0 to 36 scale.[6]
If you have PMOS, previously called polycystic ovary syndrome (PCOS),[3] you have probably heard that blood sugar and insulin are behind your chin hairs. That is partly true. Insulin is one of several drivers of androgen excess (too much testosterone and related hormones), which is what turns fine, light hair into coarse, dark hair on the face and body. For the full list of causes, see what causes hirsutism.
This article explains how insulin affects hair, how insulin resistance is tested, and which treatments that target insulin actually change hair growth.
How does insulin resistance cause facial hair?
High insulin raises androgen levels in two ways. A 2025 review in Endocrine Connections summarizes them:[1]
- More androgen production: Insulin resistance increases androgen production by the theca cells of the ovaries, both directly and by making them more sensitive to luteinizing hormone (LH), a hormone from the pituitary gland.
- Less SHBG: High insulin lowers the liver’s production of sex hormone-binding globulin (SHBG). With less SHBG, more testosterone circulates in its free, active form.
Free testosterone then reaches the hair follicles on the face, chest and abdomen, where it can gradually turn fine vellus hair into thick terminal hair.[8]
There is direct evidence for this link. In a classic 1996 trial in The New England Journal of Medicine, 24 women with PCOS and obesity took metformin or placebo for 4 to 8 weeks. In the metformin group, insulin levels fell, free testosterone dropped from 0.34 to 0.19 ng/dL, and SHBG rose.[4] In other words, lowering insulin lowered androgen activity. The trial was too short to measure hair.
How common is insulin resistance in PMOS?
About half of people with PMOS have insulin resistance as part of a metabolic syndrome, according to a major review in Endocrine Reviews. It can be related to higher weight, but it can also be intrinsic, meaning it is part of the condition itself.[2] The 2023 International PCOS Guideline states that women with PCOS have a higher risk of prediabetes and type 2 diabetes,[5] and a 2025 review notes that prediabetes affects up to 40% of women with PCOS.[1]
Insulin is not the whole story, though. Some women have hirsutism with normal insulin, and some have normal androgen levels altogether. Our PMOS facial hair guide explains the other factors.
What are the signs of insulin resistance?
Insulin resistance is linked to higher weight, but it also occurs in women who are not overweight, so your weight alone does not tell you whether you have it.[2] Because the risk of blood sugar problems is high in PMOS, the 2023 guideline recommends checking blood sugar status in all adults and adolescents with PCOS at diagnosis.[5]
How is insulin resistance tested?
The guideline recommends testing blood sugar, not insulin. It states that insulin resistance is a key feature of PCOS, but that clinically available insulin tests are of limited use and are not recommended in routine care.[5] That includes HOMA-IR, a score calculated from fasting insulin and glucose, which many women ask for.
| Test | What it measures | 2023 guideline view |
|---|---|---|
| 75 g oral glucose tolerance test (OGTT) | Blood sugar before and after a sugary drink | Recommended as the preferred test[5] |
| Fasting glucose or HbA1c | Blood sugar after fasting, or average blood sugar over the past few months | Could be used if an OGTT is not possible[5] |
| Fasting insulin or HOMA-IR | Insulin levels, or a score from insulin and glucose | Not recommended in routine care[5] |
Lab reference ranges vary by lab and test method, so always compare your results with the range on your own report. Blood sugar tests check for prediabetes and type 2 diabetes, which are more common in PMOS.[5]
What helps insulin resistance, and does it reduce hair?
Several approaches improve insulin, but none of them is a strong hair treatment on its own. Here is how they compare for unwanted hair:
| Approach | Effect on insulin or weight | Effect on hair | Evidence for hair |
|---|---|---|---|
| Lifestyle change (diet and exercise) | Lower fasting insulin and weight[6] | Hair score down about 1 point (0-36 scale)[6] | Limited |
| Metformin | Lowers insulin[4] | No better than placebo in a Cochrane review[9] | Limited |
| GLP-1 drugs (semaglutide, liraglutide) | Weight loss[10] | Not enough data; no change in trials that measured it[10] | Limited |
| Inositol | Some metabolic benefits[11] | No proven benefit vs placebo[11] | Limited |
| Combined pill, anti-androgens, hair removal | Not aimed at insulin | Proven to reduce hair[8] | Strong |
Lifestyle change and weight loss
Evidence: Limited Lifestyle change is good for PMOS, but its effect on hair is small. The 2019 Cochrane review of lifestyle changes in PCOS pooled 15 trials with 498 women. Compared with minimal treatment, lifestyle programs lowered weight, testosterone and fasting insulin, and raised SHBG. Hair scores improved by 1.12 points on average, based on 4 studies with 166 women, and the overall evidence was rated low quality.[6] A loss of 5 to 10% of body weight is considered enough to improve the metabolic and reproductive features of PCOS.[7]
The 2023 guideline recommends lifestyle intervention for all women with PCOS, mainly for metabolic and overall health.[5]
Metformin
Evidence: Limited Metformin lowers insulin and androgen activity,[4] but this has not translated into a clear hair benefit. The Endocrine Society’s 2018 guideline suggests against insulin-lowering drugs for hirsutism alone,[8] and a Cochrane review found metformin no better than placebo for hirsutism scores.[9] The 2023 International PCOS Guideline says the combined pill could be used over metformin for hirsutism, while metformin could be used over the pill for metabolic reasons.[5] See our hirsutism medication guide for more.
GLP-1 drugs (Ozempic, Wegovy, Mounjaro)
Evidence: Limited GLP-1 drugs lead to modest weight loss in women with PCOS, but a 2026 meta-analysis found too little data to judge their effect on hair.[10] The guideline supports them only for higher weight, following general population rules.[5] Read the details, including pregnancy and contraception warnings, in GLP-1 drugs for hirsutism and PMOS.
Inositol
Evidence: Limited Inositol is a supplement studied as an insulin sensitizer. In a meta-analysis of 26 trials, it improved some hormone and blood sugar measures versus placebo, but the only placebo-controlled study of hair scores found no significant benefit.[11] Read more in inositol for hirsutism.
Can changing your diet reduce facial hair?
Diet alone has not been shown to reduce facial hair. The 2023 guideline found no evidence that any one diet composition is better than another for PCOS, and says any healthy eating pattern that fits general population guidelines has health benefits.[5] Diet seems to affect hair mainly through weight and insulin, and the effect of lifestyle change on hair scores is small.[6] We look at specific foods, sugar, dairy and soy in foods that can cause facial hair growth.
Should you treat insulin resistance or the hair?
Usually both, for different reasons. Treating insulin resistance lowers your risk of type 2 diabetes and may slightly reduce androgen levels.[5][6] Treating the hair directly has much stronger evidence: The Endocrine Society recommends the combined pill as first-line medicine for most women not trying to conceive, with an anti-androgen added after 6 months if needed, together with hair removal.[8] See PMOS hair removal for methods that work well with hormonal hair.
When should you see a doctor?
See a doctor if you have unwanted hair together with irregular periods, weight gain or a family history of type 2 diabetes, so that both your hormones and your blood sugar can be checked. Go promptly if:
- Hair growth started suddenly or is getting worse within months
- You notice a deepening voice, an enlarged clitoris or other signs of virilization
- Your periods have stopped
These can be signs of a rare androgen-producing tumor.[8] Start with our hirsutism self-check.
Frequently asked questions
Can insulin resistance cause chin hair?
It can contribute. High insulin increases androgen production and lowers SHBG, leaving more active testosterone to act on hair follicles.[1]
Will losing weight get rid of facial hair?
Probably not on its own. In a Cochrane review, lifestyle changes improved hair scores by only about 1 point on a 0 to 36 scale, although they improved hormones and insulin.[6]
Can thin women have insulin resistance?
Yes. In PMOS, insulin resistance can be intrinsic to the condition, not only related to weight.[2]
Does metformin reduce facial hair?
Not much. A Cochrane review found it no better than placebo for hirsutism scores,[9] and the Endocrine Society suggests against insulin-lowering drugs for hirsutism alone.[8]
Should I ask for a HOMA-IR test?
The 2023 guideline does not recommend insulin tests such as HOMA-IR in routine care. It recommends an oral glucose tolerance test to check blood sugar instead.[5]
Key takeaways
- High insulin raises androgen production in the ovaries and lowers SHBG, which can worsen hirsutism.
- About half of people with PMOS have insulin resistance, including some who are not overweight.
- Guidelines recommend an oral glucose tolerance test, not insulin or HOMA-IR tests.
- Lifestyle change, metformin, GLP-1 drugs and inositol improve insulin but have small or unproven effects on hair.
- For unwanted hair, combine metabolic care with proven hair treatments such as the pill, anti-androgens and hair removal.
Sources
- Monney M, Mavromati M, Leboulleux S, Gariani K. Endocrine and metabolic effects of GLP-1 receptor agonists on women with PCOS, a narrative review. Endocr Connect. 2025;14(5):e240529. PubMed 40066975
- Rosenfield RL, Ehrmann DA. The Pathogenesis of Polycystic Ovary Syndrome (PCOS): The Hypothesis of PCOS as Functional Ovarian Hyperandrogenism Revisited. Endocr Rev. 2016;37(5):467-520. PubMed 27459230
- Teede HJ, Khomami MB, Morman R, et al. Polyendocrine metabolic ovarian syndrome, the new name for polycystic ovary syndrome: a multistep global consensus process. Lancet. 2026;407(10545):2329-2339. PubMed 42119588
- Nestler JE, Jakubowicz DJ. Decreases in ovarian cytochrome P450c17 alpha activity and serum free testosterone after reduction of insulin secretion in polycystic ovary syndrome. N Engl J Med. 1996;335(9):617-623. doi:10.1056/NEJM199608293350902. Link
- Teede HJ, Tay CT, Laven JJE, et al. Recommendations From the 2023 International Evidence-based Guideline for the Assessment and Management of Polycystic Ovary Syndrome. J Clin Endocrinol Metab. 2023;108(10):2447-2469. PubMed 37580314
- Lim SS, Hutchison SK, Van Ryswyk E, Norman RJ, Teede HJ, Moran LJ. Lifestyle changes in women with polycystic ovary syndrome. Cochrane Database Syst Rev. 2019;3(3):CD007506. PubMed 30921477
- Kourtidou C, Tziomalos K. Pharmacological Management of Obesity in Patients with Polycystic Ovary Syndrome. Biomedicines. 2023;11(2):496. PubMed 36831032
- Martin KA, Anderson RR, Chang RJ, et al. Evaluation and Treatment of Hirsutism in Premenopausal Women: An Endocrine Society Clinical Practice Guideline. J Clin Endocrinol Metab. 2018;103(4):1233-1257. PubMed 29522147
- van Zuuren EJ, Fedorowicz Z, Carter B, Pandis N. Interventions for hirsutism (excluding laser and photoepilation therapy alone). Cochrane Database Syst Rev. 2015;(4):CD010334. PubMed 25918921
- Forslund M, Wändell P, Forsberg L, et al. GLP-1 receptor agonist treatment in women with polycystic ovary syndrome: a systematic review and meta-analysis. Eur J Endocrinol. 2026;194(3):S25-S39. PubMed 41701618
- Greff D, Juhász AE, Váncsa S, et al. Inositol is an effective and safe treatment in polycystic ovary syndrome: a systematic review and meta-analysis of randomized controlled trials. Reprod Biol Endocrinol. 2023;21(1):10. PubMed 36703143
This article is for education and is not medical advice. Talk to a doctor about diagnosis and treatment.