The link between PCOS and insulin resistance

PCOS is a metabolic disorder that is intricately tied to insulin resistance. Here's how the two conditions influence each other.


Article highlights

  • Polycystic ovary syndrome (PCOS) is a complex condition that involves multiple systems in the body, including our reproductive hormones and metabolic health.
  • PCOS presents with an irregular or absent menstrual cycle, cysts in the ovaries, and high androgen levels (i.e., too many “male” sex hormones).
  • Poor metabolic health—specifically, insulin resistance—can cause or contribute to PCOS.
  • Excess insulin stimulates the ovaries to produce more androgen hormones, while high androgen levels can worsen insulin resistance—creating a vicious cycle.
  • Focusing on lifestyle changes related to decreasing insulin resistance can often help with managing PCOS, decreasing symptoms, and lowering associated risks.

Polycystic ovary syndrome (PCOS) is a complex condition that affects 6-12% of people who menstruate in the US and up to 20% worldwide.

Despite what the name suggests, polycystic ovary syndrome doesn’t just affect the ovaries; it involves multiple systems in the body. Often overlooked is the link between PCOS and metabolic health.

Metabolic health is the set of processes that determine how well we generate and process energy in the body. The primary metabolic issue related to PCOS is insulin resistance.

Researchers estimate that around 50-90% of people with PCOS have insulin resistance. The connection is bi-directional: insulin resistance can contribute to PCOS, and PCOS can also exacerbate insulin resistance. This link is so crucial to understanding PCOS that some have even suggested we call PCOS a metabolic disease.

Understanding how PCOS and insulin resistance impact one another can help to manage both conditions and their associated long-term health risks. Here, we’ve broken down what you need to know about this relationship.

PCOS 101

PCOS is a hormonal disorder characterized by an irregular or absent menstrual cyclecysts in the ovaries, and an excess of “male” hormones called androgens (which include testosterone). According to the Rotterdam criteria, you must show two of the above to be diagnosed with PCOS.

Note: just having cysts on the ovaries does not mean you have PCOS, as these are commonly found in healthy women.

PCOS presents various symptoms, including acne, irregular periods, hair loss on the head, and excess hair growth on the face and body (hirsutism). It can also lead to more significant health issues such as infertilitydiabetes, and heart disease.

PCOS is a heterogeneous disease, meaning that it can have multiple causes. We need more research to understand these better, but we know that high levels of androgens and insulin resistance can play a role in both causing and exacerbating PCOS.

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What is insulin resistance?

Insulin is a hormone produced by the pancreas that helps keep glucose in check. When we eat carbohydrates, they convert into a type of sugar called glucose, a primary fuel source (along with fat) for all of the cells in our body. That glucose enters our bloodstream so it can be distributed throughout the body. Insulin makes it possible for glucose to enter cells to be used for energy or storage if all our current energy needs are met.

If we consume high amounts of carbohydrates (including sugar), the level of glucose in our blood can rise faster than insulin can deal with it. This is known as a glucose—or blood sugar—spike. Other things besides diet can also cause a spike in glucose, such as intense exercise and acute stress.

A blood sugar spike causes our body to release even more insulin. When this happens repeatedly, insulin becomes less effective over time, as cells become “numb” to its effect. This produces more insulin to compensatewhich only exacerbates the cycle. Insulin resistance refers to cells no longer effectively listening to the cue to bring in glucose.

Over time, as increased insulin resistance leads to chronically high blood sugar, it can result in prediabetes and, ultimately, Type 2 diabetes. Insulin resistance can also increase the risk of many other cardiometabolic and reproductive conditions, as well as contribute to or exacerbate PCOS. 

What are androgens, and why do they matter?

Insulin resistance is mainly linked to one element of PCOS: high levels of androgens.

Androgens include testosterone, androstenedione, dihydrotestosterone (DHT), and dehydroepiandrosterone (DHEA). They are called “male” hormones because they give men their male characteristics, such as testes.

However, don’t let this label fool you. Females also produce androgens and have higher androgen levels than estrogen most of the time. Healthy androgen levels are critical for reproductive function, libido, cardiometabolic health, and building healthy bones and muscles.

However, when androgens are too high, it is called hyperandrogenism—one of the three core factors that can lead to a PCOS diagnosis. Hyperandrogenism is responsible for many unwanted PCOS symptoms, such as acne, excess body hair, or hair thinning on the head. It also can play a critical role in infertility. Finally, high androgen levels link insulin resistance – and its associated cardiometabolic health risks – to PCOS.

How do PCOS and insulin resistance exacerbate each other?

Unfortunately, when insulin and androgen levels are too high, these hormones egg each other on.

Excess insulin can stimulate specific cells in the ovary, called theca cells, into producing more androgens than normal. The ovaries remain sensitive to insulin, even when other body parts—such as muscles, fat, or the liver—become insulin resistant. As your body makes more insulin, the ovaries continue to respond to insulin production, causing androgen levels to climb higher and higher.

Elevated insulin levels can also decrease levels of sex hormone-binding globulin (SHBG). As its name suggests, SHBG is a protein that binds to androgens, controlling the number of these hormones circulating in the body and keeping levels in a healthy range. When there is not enough SHBG, androgen levels remain higher than they should be.

Higher levels of androgens can also make insulin resistance worse. Excess androgens in women can cause fat to accumulate around the abdomen. These fat tissues then trigger the release of specific signals impairing the body’s sensitivity to insulin. Excess androgens can also worsen insulin resistance by reducing insulin sensitivity in skeletal muscle.

These two types of hormones continue to instigate each other in a vicious cycle, ultimately worsening both PCOS and insulin resistance. This can lead to increased PCOS symptoms, both those caused by high androgens (acne, excess hair growth on the face and body) and insulin resistance (increased belly fat, trouble losing weight).

Not only are the symptoms of PCOS linked to androgens and insulin, but these two hormones also drive the more severe risks of PCOS in most cases. These include reproductive risks like infertility and pregnancy complications, issues with weight and obesity, and other metabolic conditions ranging from heart disease and diabetes to sleep apnea. For more on the risks associated with PCOS, click here.

Here’s where diagnosing PCOS gets complicated…

Diagnosing PCOS is a notoriously fuzzy process. Up to 84% of women aged 18-30 have polycystic ovaries. Hyperandrogenism and anovulation are challenging to measure objectively and lack clear clinical standards. Moreover, there are no separate criteria for adolescence or menopause, despite global agreement that hormonal changes during these stages of life can influence the diagnostic markers for PCOS. Diagnosing PCOS amidst the hormonal fluctuations of shifting life phases is difficult, but the resulting ambiguity can lead people to be overdiagnosed, underdiagnosed, or misdiagnosed.

Most significantly, there are significant issues with PCOS’ complicated, highly-debated diagnostic criteria, particularly regarding the role of androgens and insulin. Technically, not all people diagnosed with PCOS have both high androgens and insulin, and, according to the Rotterdam criteria, some don’t have either.

As mentioned above, to have a PCOS diagnosis according to the Rotterdam criteria, two of the following symptoms are needed: high androgens, irregular cycles, and cysts on the ovaries. These criteria are based on expert opinion rather than informed by epidemiological data.

There is substantial controversy as to whether those with only irregular cycles and cysts should be considered to have PCOS, particularly if they don’t have high insulin levels. The Androgen Excess Society put forward criteria in 2006 that require hyperandrogenism. Meanwhile, some researchers have called for greater awareness of the link between metabolic conditions and PCOS, while others have said that screening for insulin resistance should be a part of the diagnostic procedure.

The argument for including those without hyperandrogenism within PCOS diagnostic criteria is to widen the scope of inclusion under the assumption that more people having a diagnosis would lessen the risks associated with PCOS for these people.

However. research demonstrates that women without dysregulated androgens or insulin do not have the same symptoms or risks. This aligns with the mechanistic understanding that the significant symptoms and risks for PCOS (weight gain, acne, excess body hair, cardiometabolic risks) stem from high androgens, insulin resistance, or bothMoreover, the most common treatments for PCOS, such as hormonal contraception or metformin, specifically target lowering androgens or insulin resistance.

The role of a diagnosis is to provide insight into risk assessment and treatment pathways. The current criteria for PCOS do not provide enough specificity to do this properly. Instead, the broadness of the criteria hinders the ability of patients to get the proper treatment.

A better, more comprehensive diagnostic criteria would consider the many hormonal factors and potential subtypes. Until then, determining the impact of androgens, insulin, or both is a sound approach for targeted PCOS management.

How do I know if I have insulin resistance or high androgens?

Given the ambiguity in diagnosing PCOS, assessing your hormone levels and metabolic health is vital to figure out what’s causing your symptoms.

A clinician can diagnose androgen excess with bloodwork or by assessing symptoms, such as acne, hair growth on the body, or hair loss on the head. While there is no consensus on an upper cut-off, your doctor can tell you if your results are above a healthy range, particularly in the context of other symptoms.

You can measure metabolic health through glucose and insulin testing at the doctor’s office. The optimal ranges for metabolic testing are covered in this guide. However, this also gives one snapshot in time. Further testing may be beneficial to get a better sense of whether or not your body has more significant glucose spikes than expected, suggesting possible insulin resistance.

You can test glucose levels with over-the-counter finger-prick tests or continuous glucose monitors to get a series of data points. While the delta between glucose levels for healthy women and those with PCOS has not yet been established in research, understanding optimal and suboptimal levels can help illuminate the state of your metabolic health.

How to reduce insulin resistance to improve PCOS

When insulin resistance decreases, it also reduces the level of androgens in the body, reversing their effects. Thus, lowering insulin resistance can help most PCOS patients for whom insulin resistance is a factor.

The good news is that we can improve our insulin resistance by making specific lifestyle changes that decrease the body’s need to produce insulin. These include: