Insulin resistance: Causes, symptoms and treatment

The hormone insulin plays a key role in the way the body processes glucose and turns it into usable energy. However, the body becomes less responsive to insulin, which can lead to a condition called insulin resistance. Read on for more about this condition, including symptoms and management techniques.

In this article:

What is insulin?

Insulin is an important hormone in the body. It plays a key role in the way the body processes glucose, a sugar molecule derived from the food that we eat daily. When systems are running normally, insulin helps the body maintain balanced blood glucose levels, ensuring that we have the energy we need daily.

Understanding insulin and its role in the body

When someone eats carbohydrates, their body converts them into glucose. The glucose then circulates throughout the bloodstream as a means of cellular energy. As the glucose levels in the blood temporarily spike, insulin is produced and released into the bloodstream by the pancreas, one of the internal organs. This balances the spike and brings the body back into a state of equilibrium (or homeostasis).

At the same time, insulin directs glucose and helps it enter cells, like those in fat tissue, muscles and organs, throughout the body. Glucose is then converted into energy or stored for later as glycogen.

What is insulin resistance?

Insulin is critically important. Without it, the body wouldn’t be able to convert glucose into energy, and blood sugar levels would remain high. But sometimes, the insulin-glucose regulation process becomes unbalanced.

If someone has been diagnosed with insulin resistance (also called impaired insulin sensitivity) their body may be resistant to the effects of insulin. As a result, the pancreas might try to produce more insulin to compensate, potentially worsening the problem.

What’s the long-term impact of insulin resistance?

People living with insulin resistance have a higher risk of developing prediabetes and even type 2 diabetes.

Beyond these conditions, elevated blood sugar levels over time can cause a number of negative health effects. One common complication of long-term insulin resistance, for example, is that the body stores excess blood sugar, which it can’t process as fat, possibly resulting in weight gain over time.

Having higher-than-normal blood glucose levels can either indicate prediabetes or diabetes. Some people with insulin resistance and prediabetes go on to have type 2 diabetes; the more resistant to insulin someone is, the harder the disease is to manage.

Common symptoms of insulin resistance

Insulin resistance can occur without any symptoms at all. However, some might notice common symptoms:

• Darkened skin in the armpit or on the back of the neck, called acanthosis nigricans. This “strongly suggests the presence of insulin resistance,” says Jennie Stanford, MD, dual board certified in family medicine and obesity medicine.
• Skin tags in the armpit or on the back of the neck.

If someone suspects they have these skin changes, Dr. Stanford says they should talk to a health care provider about testing their insulin and glucose levels.

Less common symptoms of insulin resistance

Several metabolic conditions may trigger or increase the risk of insulin resistance, including polycystic ovarian syndrome (PCOS), certain hormonal disorders and metabolic syndrome.

Infrequently, people with insulin resistance might also experience eye changes that can lead to retinopathy, a serious eye condition. It’s important for someone to let a health care provider know if they notice symptoms like blurred vision or vision changes.

What causes insulin resistance?

Experts are still learning why some people start to develop a resistance to insulin. However, we do know that certain lifestyle and genetic factors can increase the risk. The most common risk factors of insulin resistance include the following:

• Being age 45 and up
• Having a close family member with diabetes
• Having certain conditions, including abdominal adiposity (excess fat around the midsection), fatty liver disease, gestational diabetes, heart disease,  high blood sugar, high cholesterol, metabolic syndrome or PCOS
• Living a sedentary lifestyle
• Obesity

Acquired causes of insulin resistance

Some risk factors for insulin resistance are acquired, which means an individual isn’t born with them. For example, having excess body fat, not getting enough physical activity and eating an unhealthy diet are all acquired factors that may make someone more likely to experience insulin resistance. Certain medications may also increase the risk, including glucocorticoids (or steroids) and antipsychotics.

Other possible causes of insulin resistance include the following:

• Genetic conditions. Genetics can play a role in the way someone’s body processes insulin. Insulin resistance — sometimes in a very severe form — can accompany a number of genetic conditions, including type A insulin resistance syndrome, Rabson-Mendenhall syndrome and Donohue syndrome. Someone is also more likely to develop insulin resistance if one of their immediate family members (a parent, brother or sister, for example) is living with diabetes.
• Hormonal disorders. Having certain hormonal disorders, such as Cushing’s syndrome, might increase the risk of insulin resistance. Though more studies are needed, some research suggests there’s also a link between insulin resistance and hypothyroidism.
• Insulin resistance and PCOS. Polycystic ovary syndrome (PCOS) is a hormonal condition. It can affect reproductive-aged women, possibly leading to irregular periods, hormonal imbalances or difficulties getting pregnant. Anywhere from 30 to 70 percent of patients living with PCOS may develop insulin resistance.

Diagnosing insulin resistance

It’s important for health care providers to consider a combination of factors when diagnosing insulin resistance, including looking at someone’s overall medical history and running tests. The most common tests for insulin resistance include fasting insulin levels, fasting plasma glucose (FPG), hemoglobin A1c (HbA1c) and oral glucose tolerance tests to see if someone may be experiencing insulin resistance or prediabetes.

An elevated fasting insulin level can be enough to diagnose insulin resistance, and fasting glucose and HbA1c levels may suggest the progression to prediabetes or type 2 diabetes.

Family and medical histories

During an appointment, a health care provider will likely review their patient’s family and medical history. For example, they’ll probably ask if any family members have diabetes, what other health conditions the patient may have and if they’re currently taking any medications. They’ll also go over any symptoms someone might be experiencing (though, some people living with insulin resistance show no signs at all).

Lastly, a health care provider might also discuss any lifestyle factors that might increase the risk of having this condition, such as being overweight or not getting enough exercise.

Risk factors for insulin resistance

Experts are still learning why, exactly, some people develop a resistance to insulin and others don’t. The risk for developing the condition may be higher for people who:

• Are overweight or have obesity.
• Maintain a sedentary lifestyle.
• Have high total cholesterol, high triglycerides or low levels of HDL (“good”) cholesterol.
• Have high blood sugar.
• Have a family history of type 2 diabetes.
• Live with coexisting health conditions, such as heart disease, PCOS or Cushing’s syndrome.
• Are a descendant of certain races or ethnicities, including African American, Alaska Native, Asian American, Hispanic/Latino, Native American, Native Hawaiian or Pacific Islander.

Insulin resistance management and prevention

Lifestyle changes like eating well, getting enough exercise and taking steps to lose weight are the main strategies health care providers recommend to both prevent and manage insulin resistance.

Adequate sleep

Getting enough high-quality sleep is important for overall health, and it can support the body’s insulin production process, too. Studies have repeatedly linked insulin resistance and type 2 diabetes with shorter and poorer quality sleep. In one recent systematic review, researchers found that people suffering from sleep deprivation were significantly more likely to have insulin resistance. Generally, it is best to aim for around seven hours a night.

Healthy diet

Eating plenty of non-starchy fresh fruits and veggies, lean proteins, and minimally processed, lower-glycemic carbohydrates (like whole grains) can help to improve insulin resistance in many.

This is because these foods have a lower glycemic index, which means they lead to less of a rise in blood glucose, less insulin released and more-balanced blood glucose levels overall.

Losing weight

Eating well and exercising can help people maintain a healthy weight, which is important to manage insulin levels and help prevent diabetes.

Research shows that people at a high risk of developing insulin resistance could lower their risk if they lost five to seven percent of their body weight.

Medications

While there aren’t any medications specifically approved to treat insulin resistance, a health care provider might prescribe medication to help improve insulin sensitivity, like metformin or one of the newer glucagon-like peptide-1 (GLP-1) receptor agonists.

Physical activity

Getting enough exercise helps increase the body’s sensitivity to insulin so it can maintain balanced blood glucose levels. For substantial health benefits, the latest physical activity guidelines recommend that adults do at least 150 to 300 minutes of moderately intense exercise a week.

Ideally, the chosen exercise routine should include both cardiovascular exercise and resistance training to help burn calories, maintain lean muscle mass and improve insulin sensitivity. Discuss any significant changes to activity with a health care provider.

Stress management

Taking steps to manage stress can benefit overall health in countless ways, and that includes helping to keep blood glucose levels balanced. Higher levels of both physical and emotional stress have been linked to type 2 diabetes. Some research suggests that stress interferes with glucose homeostasis, the process that keeps glucose levels balanced.

When to talk to a health care provider

People should let their health care provider know if they notice symptoms of insulin resistance, such as skin tags or darkened skin in the armpit or on the back of the neck. Someone may also consider a visit if they’re experiencing symptoms associated with type 2 diabetes or other conditions, such as blurry vision, excessive thirst, fatigue, frequent urination, tingling in hands or feet, or unusual hunger.

However, because many people who are insulin resistant don’t have any symptoms at all, it’s important to have regular checkups with a health care provider to monitor overall health.

At these appointments, a health care provider can review medical history. They may also recommend testing blood sugar if someone has any prediabetes or insulin-resistance risk factors.

It’s important for people to stay informed and be on the lookout for early warning signs to discuss with their health care provider.

Frequently asked questions

What is the main cause of insulin resistance?

Experts are still learning why some people develop insulin resistance. However, health experts do know that certain factors increase the risk of developing insulin resistance. These factors include obesity, a sedentary lifestyle, a family history of diabetes and PCOS.

How does someone know if they’re insulin resistant?

It’s important to speak to a health care provider if someone is experiencing symptoms of insulin resistance, like skin tags, darkened skin on the body, vision changes or weight changes. However, because so few people living with insulin resistance experience any symptoms, it’s important to stay in regular contact with a health care provider, who can conduct ongoing screening of blood glucose and insulin levels.

What foods may contribute to insulin resistance?

A diet high in added sugars, processed foods and refined carbohydrates can increase the risk of developing insulin resistance. Following a healthy, low-glycemic diet can help reverse insulin resistance or lower the risk of developing insulin resistance and prediabetes over time. Good choices to consider for people wanting to reduce their risk profile include plenty of fruits and non-starchy veggies, lean proteins and minimally processed carbohydrates.

What’s the difference between insulin resistance and diabetes?

If someone is diagnosed with insulin resistance, it means that their body isn’t processing glucose correctly and their blood sugar levels are spiking to higher levels as a result. This doesn’t necessarily indicate the presence of type 2 diabetes, yet. However, insulin resistance and prediabetes can lead to type 2 diabetes. This is why it’s important for people to discuss ways to minimize risk with their health care provider. Options may include eating a balanced diet, getting regular exercise and maintaining a healthy weight.

What’s the difference between insulin resistance and insulin sensitivity?

Insulin sensitivity refers to how well the body responds to insulin. If someone lives with insulin resistance, their insulin sensitivity is likely impaired and possibly compromising the body’s ability to process glucose and respond to insulin changes. This is commonly seen in those living with insulin resistance.

This content is for informational purposes only and is not medical advice. Consult your health care provider before taking any vitamins or supplements and prior to beginning or changing any health care practices.