Insulin resistance means your body does not respond to insulin as well as it should. Insulin is a hormone that helps sugar (glucose) move from your blood into your cells. The World Health Organization (WHO) says PCOS (polycystic ovary syndrome) is linked with a higher long-term risk of insulin resistance and type 2 diabetes.
This page explains the idea. It is health information for learning and planning, not medical advice. Only your clinician can say what your own blood tests mean.
Seek care now: If you take metformin, call your local emergency number or go to the nearest emergency department if you have signs of too much acid in the blood (lactic acidosis). The NHS lists being sick, stomach pain, muscle cramps, breathing problems and feeling very tired as signs. Do the same for signs of a severe allergic reaction, such as a swollen throat or tongue, a raised itchy rash, or trouble breathing.
What insulin resistance is
The US National Institute of Diabetes and Digestive and Kidney Diseases (NIDDK) describes insulin resistance as a condition where your body does not respond to insulin the way it should. Insulin is made by the pancreas, an organ in your tummy.
When cells do not respond well, more sugar can stay in the blood. Over time, this can lead to higher blood sugar levels. NIDDK lists PCOS among the conditions that raise the chance of insulin resistance and prediabetes. Prediabetes means blood sugar is higher than usual, but not high enough to be type 2 diabetes.
Insulin resistance is not the same as diabetes. NIDDK says people with insulin resistance and prediabetes usually have no symptoms. That is why blood tests matter more than how you feel.
Why it matters with PCOS
WHO says women with PCOS have a higher risk of other health conditions. These include type 2 diabetes, high blood pressure and heart disease. After a PCOS diagnosis, WHO advises further blood tests. These look for insulin resistance and check overall heart and blood vessel risk.
The NHS lists thick, dark patches of skin on the neck or armpits among possible PCOS symptoms. Tell your clinician about any skin change like this.
How a clinician checks blood sugar
Insulin itself is not usually measured. The 2023 international PCOS guideline says insulin tests that clinics can order have limited value and are not recommended in routine care. NIDDK also says the insulin resistance test is mainly used in research.
Instead, the guideline names the 75-gram oral glucose tolerance test (OGTT) as the most accurate way to check blood sugar in PCOS. MedlinePlus, from the US National Library of Medicine, explains how it works:
- You do not eat for at least 8 hours before the test.
- A first blood sample is taken.
- You drink a sweet liquid that contains a set amount of glucose.
- More blood samples are taken over the next few hours.
If an OGTT cannot be done, the guideline says two other tests may be used. These are less accurate:
- Fasting glucose measures blood sugar after you have had nothing but water for at least 8 hours.
- HbA1c shows your average blood sugar over the past two to three months.
The guideline says an OGTT should be offered to all women with PCOS who are planning a pregnancy or seeking fertility treatment.
Lifestyle and blood sugar
NIDDK says healthy food and drinks and being active may help reverse insulin resistance and prediabetes. The PCOS guideline says lifestyle support aims to improve metabolic health, such as blood sugar and blood fat levels. It also says healthy habits help even without weight loss. See the lifestyle and weight guide.
What metformin is
Metformin is a prescription-only medicine. The NHS says it is used for type 2 diabetes, for gestational diabetes (diabetes that starts in pregnancy) and for PMOS. The NHS now uses the name PMOS (polyendocrine metabolic ovarian syndrome), which it says used to be called PCOS. You may hear both names.
The 2023 guideline says metformin may be considered for some adults with PCOS. Its main use is metabolic health, such as insulin resistance, blood sugar and blood fats. The evidence behind this is limited. For extra hair, the guideline prefers the combined pill over metformin. Your clinician decides with you whether metformin fits your goals.
Like all medicines, metformin can cause side effects. The NHS lists these common ones:
- feeling or being sick
- diarrhoea
- tummy pain
- loss of appetite
- a change in how things taste
The guideline says stomach side effects are often mild and tend to ease over time. Both the NHS and the guideline say metformin can lower vitamin B12 levels, which can make you tired. Serious side effects are rare. The warning signs are in the box near the top of this page.
Questions to ask your clinician
- Do I need a sugar drink test (OGTT) or another blood test?
- What would a result change in my plan?
- Is metformin an option for my goals, and which side effects matter for me?
- Should I have my vitamin B12 checked?
- Should I have a check for heart and blood vessel risk?
- When should we repeat my blood sugar checks?
When to see a doctor
Book a visit if you have PCOS and have not had any blood sugar checks. If you are planning a pregnancy or fertility treatment, ask about an OGTT.
The NHS lists signs of type 2 diabetes that are worth a GP visit. These include feeling very tired, passing urine more than usual, feeling thirsty all the time, and losing weight without trying. Blurred vision, cuts that heal slowly, and itching around the vagina or repeated thrush are also on the list.
Book a visit if a medicine causes side effects that worry you. Talk to your clinician before you make any change to a prescribed medicine.
What femio does and does not do. femio can help you keep notes on cycles, skin changes and questions for your visit. femio does not measure insulin, read your blood tests, or choose a medicine. femio does not diagnose PCOS or insulin resistance, and it is not medical advice.