Blood Sugar and Female Hormones: PCOS, Periods and Menopause
Your reproductive hormones and metabolic health influence one another throughout life. Insulin is part of that conversation, especially in PCOS, while changing oestrogen levels around menopause can affect the way your body stores and uses energy.
Understanding these links can help you choose useful changes without feeling that every symptom needs a different supplement or that every carbohydrate is a problem.
What’s covered
- Insulin, SHBG and ovarian androgen production.
- Ovulation, progesterone and irregular periods.
- Menstrual cycle changes and menopause.
- Food-first nutrition and avoiding under-fuelling.
- Inositol, vitamin D, magnesium, iron, B12 and herbal products.
- When testing or medical treatment is needed.
Insulin and PCOS
PCOS is a complex condition involving reproductive and metabolic health. Insulin resistance is common, including in people who are not living with overweight. However, it is not present to the same degree in everyone, and PCOS cannot be diagnosed from insulin-related symptoms alone. [1]
In susceptible ovaries, higher insulin levels can amplify androgen production. Insulin resistance is also associated with lower SHBG, increasing the availability of testosterone. This can contribute to excess hair growth, acne and disrupted follicle development. [1]
Testosterone is not exclusively a male hormone: women need it too. The issue is excess androgen activity in the context of an individual’s symptoms and test results.
Ovulation and progesterone
Following ovulation, the corpus luteum produces progesterone. If ovulation does not happen, that usual rise does not occur.
Periods may become infrequent or unpredictable. Over time, prolonged gaps between periods can increase the risk of thickening of the womb lining in PCOS. Lifestyle support is valuable, but it does not replace discussing cycle regulation and endometrial protection with your GP. [1]
The phrase “oestrogen dominance” is often used online, but it is not a precise diagnosis. Heavy bleeding, PMS and breast tenderness do not show that insulin has made oestrogen too high. They need their own clinical context.
Changes across the menstrual cycle
Some women notice changes in appetite, energy or exercise tolerance across their cycle. Glucose responses can also vary, particularly for people with diabetes. The size and pattern of these changes differ between individuals.
There is no established need for every woman to follow a rigid cycle-based diet. Keeping a short record of symptoms, meals, sleep and bleeding may help identify patterns worth discussing. If you have diabetes, your diabetes team can help with recurring cycle-related glucose changes.
Perimenopause and menopause
During perimenopause, oestrogen and progesterone fluctuate before ovarian hormone production settles at lower levels after menopause. Alongside ageing, changes in body composition and sleep can make metabolic health harder to maintain.
Hot flushes and night sweats can disrupt sleep, while tiredness can make movement and meal preparation harder. This can become a difficult cycle, even when your eating habits have changed very little.
Food and lifestyle support can help protect muscle, bone and cardiometabolic health. They do not reliably replace hormone replacement therapy or other evidence-based treatment when these are appropriate. HRT should be considered in relation to symptoms, medical history and individual benefits and risks, rather than used solely as a blood sugar treatment. [2]
A food-first approach
Nourish rather than continually restrict
Include protein at meals, varied vegetables and fruit, fibre-rich carbohydrates and unsaturated fats. A Mediterranean-style pattern is one practical way to bring these together.
For PCOS, the international guideline does not identify one specific dietary composition as superior for everyone. An eating pattern you can sustain, adapted to preferences and health needs, matters more than a named “hormone diet”. Health benefits can occur without weight loss. [1]
Protect muscle and bone
Adequate protein and resistance exercise help maintain muscle. Calcium-rich foods include dairy foods, calcium-fortified alternatives, calcium-set tofu and some fish eaten with their bones. Check labels, as plant alternatives vary.
Vitamin D supports calcium absorption and bone health. UK advice is to consider 10 micrograms daily during autumn and winter; some people need this throughout the year. Higher doses should be based on clinical need. Excess vitamin D can cause high calcium and damage health. [3]
Avoid under-fuelling
Periods can stop because too little energy is available for the body’s needs, particularly alongside high exercise loads. This can happen at different body sizes. It is a different situation from assuming insulin is too high and may require increasing food intake and adjusting training. [4]
Supplements: what may be relevant?
Inositol
Inositol may be considered in PCOS according to individual preferences. The 2023 guideline describes possible metabolic improvements but limited clinical benefits for outcomes such as ovulation, weight and excess hair growth. It cannot recommend a specific form, dose or combination because the evidence is insufficient. Its use for PCOS-related infertility remains experimental. [1]
This is a discussion to personalise, rather than a supplement every woman with PCOS needs.
Magnesium and vitamin D
Magnesium-rich foods include nuts, seeds, legumes, wholegrains and leafy vegetables. Correcting inadequate intake is sensible, but supplementation is not an established universal treatment for hormone symptoms. Magnesium supplements may cause diarrhoea and need particular care in kidney disease. [5]
Vitamin D is relevant to bone health and deficiency prevention. Having PCOS or menopause symptoms does not, by itself, justify high-dose vitamin D. [3]
Iron and B12
Heavy menstrual bleeding can contribute to iron deficiency. Persistent tiredness, breathlessness or palpitations may warrant a full blood count and ferritin assessment. Iron supplements should address a demonstrated need and the cause of blood loss should also be investigated. [6]
Vitamin B12 deserves attention with vegan diets and in people taking metformin. Metformin can reduce B12 levels; testing is advised when deficiency is suspected, and periodic monitoring may be appropriate in those with risk factors. [7]
Omega-3, berberine and hormone blends
Oily fish can form part of a healthy eating pattern. Omega-3 supplements are not a general treatment for PMS, PCOS or menopause, and high-dose products should be considered for a specific reason.
Berberine is marketed for insulin resistance, but variable products, drug interactions and limited evidence for long-term outcomes make it unsuitable as a casual substitute for prescribed care. Avoid self-prescribing it during pregnancy or breastfeeding. “Hormone balance” blends, DIM and high-dose nutrient combinations also need scrutiny: changing hormone metabolism is not automatically beneficial. [8]
If pregnancy is possible or planned, review all supplements and medicines with a qualified clinician. Standard UK preconception advice includes 400 micrograms of folic acid daily before pregnancy and through the first 12 weeks, with higher prescribed doses for certain risk factors. [9]
When to ask for help
Seek assessment for persistent irregular periods, prolonged gaps between periods, new excess hair growth, difficulty conceiving or heavy bleeding. Any bleeding after menopause should be checked promptly.
Medical assessment can distinguish PCOS, thyroid disease, pregnancy, under-fuelling and other causes. Depending on the situation, treatment may include cycle protection, metformin, fertility treatment, HRT or other care alongside nutrition support. [1,2]
You do not need to solve this with food alone. I can help you develop a nourishing, manageable plan that complements your healthcare and takes your wider wellbeing into account.
Related reading: How Blood Sugar Affects Your Hormones.
References and further reading
1. Teede HJ et al. 2023 International Evidence-based PCOS Guideline recommendations. doi:10.1210/clinem/dgad463. Guideline resources.
2. NICE. Menopause: identification and management NG23.
3. NHS. Vitamin D.
4. Gordon CM et al. Functional Hypothalamic Amenorrhea: An Endocrine Society Clinical Practice Guideline. JCEM. 2017;102:1413–1439. doi:10.1210/jc.2017-00131.
5. NIH Office of Dietary Supplements. Magnesium: Health Professional Fact Sheet.
6. NICE. Heavy menstrual bleeding NG88. NHS. Iron deficiency anaemia.
7. MHRA. Metformin and reduced vitamin B12 levels: new advice for monitoring patients at risk.
8. NCCIH. Berberine and Weight Loss: What You Need To Know.
9. NHS. Vitamins supplements and nutrition in pregnancy.
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