What is insulin resistance—and can you reverse it?

What is insulin? | What is insulin resistance? | Causes and risk factors | Symptoms | Diagnosis | How to reverse insulin resistance

Insulin resistance is a condition in which your cells “resist” taking in insulin. Insulin is a hormone made by the pancreas. It allows glucose (or sugar) to enter the cells of your muscles, fat, and liver, where it’s used for energy. 

When your cells become less responsive to the effects of insulin—aka, you become insulin resistant—glucose builds up in your blood and less is absorbed into the cells. In an effort to get excess sugar out of the bloodstream and into your cells, the pancreas increases insulin production. At first the boost in insulin can stave off blood sugar issues, but eventually the cells get worn out and blood sugar rises, which leads to a whole host of problems, such as prediabetes, diabetes mellitus, and even heart disease and vision loss.

What is insulin?

Insulin is a hormone that primarily serves to regulate blood sugar—aka glucose. 

Sugar enters your bloodstream from the foods you eat—mainly carbohydrates (like bread and pasta), fruit, dairy, processed foods, and sweets. In response to the influx of sugar, the pancreas makes insulin. When the body works optimally, the insulin binds to insulin receptors on your cells, helping the cells take in glucose where it’s then used for energy. Excess glucose is efficiently stored in the liver until it’s released into the body when glucose levels start to dip, such as between meals.

In addition to controlling blood glucose levels, insulin also helps your body’s cells take in amino acids and fatty acids. Amino acids are necessary for the body to build protein and fatty acids help cells and tissues function normally.

What does insulin resistance mean?

Insulin resistance is a condition in which your cells become resistant—or less sensitive—to the insulin your pancreas naturally makes. Research indicates it affects 32% of Americans. Worldwide, the incidence ranges from 15% to 46% of adults. 

Why your body may start resisting insulin isn’t exactly clear. But when it does occur, glucose doesn’t get absorbed into the cells the way it should, so higher-than-normal glucose levels remain in the bloodstream. In response to the elevated blood sugars, the pancreas amps up production of insulin in an effort to get the glucose into the cells.

For a while, that increased insulin production can help keep blood sugar levels under control—which is why insulin resistance often doesn’t produce symptoms. And if insulin resistance and pre-diabetes is diagnosed and managed early, insulin resistance may never lead to diabetes. 

But when insulin resistance continues unabated, the insulin-producing cells in the pancreas eventually stop working properly and conditions like prediabetes and Type 2 diabetes—in which your pancreas either doesn’t make enough insulin or the body doesn’t use it effectively—emerge. By contrast, Type 1 diabetes is typically an inherited condition in which the pancreas doesn’t make any insulin.

According to the CDC, Type 2 diabetes is diagnosed when fasting blood sugar level is 126 mg/dL or above. Prediabetes is when your levels are 100-125 mg/dl. 

“Insulin resistance simply means your body is needing higher-than-normal amounts of insulin to maintain normal sugar levels,” says Rose Lin, MD, an endocrinologist at Providence Saint John’s Health Center in Santa Monica, Calif. “Prediabetes, on the other hand, is defined by either an elevated fasting glucose or an elevation in postprandial [after a meal] glucose values. Both can signify the presence of insulin resistance.”

Causes and risk factors

No one really knows the causes of insulin resistance. Experts do know who has increased risk of developing insulin sensitivity. Some of the risk factors include:

Family history

Family history of metabolic disorders, including insulin resistance and diabetes, puts you at increased risk of developing those conditions, too. In fact, one study notes that having a parent with diabetes increases your risk threefold.

Obesity

It’s not entirely clear why obesity may lead to insulin resistance, but it’s thought that obesity causes low-grade-but-widespread inflammation throughout the body. Of particular note is “central” fat, or fat that collects around your belly. “This is known as visceral fat,” says Daniel Reichert, MD, a family physician with Loma Linda University Health. “This type of fat produces cytokines, which are proteins that modulate inflammatory processes. They can also cause insulin to not work the way it should.” According to the NIH’s National Institute of Diabetes and Digestive and Kidney Disorders (NIDDK), it’s been shown that men who have a waist measurement of 40 inches or more and women at 35 inches or more are at greater risk of insulin resistance.

Ethnicity 

Research shows that those who identify as non-Hispanic White and African American have higher levels of insulin resistance than those who are Hispanic White and East/South Asian.

Physical inactivity

Being sedentary can increase your risk of diabetes, heart disease, and certain cancers. “Again, it isn’t entirely clear why [inactivity influences insulin resistance], but it may have something to do with cytokines and their inflammatory response,” Dr. Reichert says.  

Age

The American Diabetes Association (ADA) notes that older people are at increased risk of developing insulin resistance. Some theories include the fact that older individuals may be more likely to be overweight or obese, be less physically active, and have impaired cell function that leads to problems with insulin. 

Polycystic ovary syndrome (PCOS)

This is a hormonal disorder that affects up to 10% of women of childbearing age, reports the Office on Women’s Health. Without the proper balance of hormones, women with PCOS experience problems ovulating, menstruating, and getting pregnant. They also develop problems regulating insulin. Up to 70% of women with PCOS have insulin resistance and, because of this, they have too much insulin circulating in their blood (called hyperinsulinemia). 

Poor sleep

Sleep deprivation increases inflammatory proteins, oxidative stress (an overabundance of unstable molecules in your body that cause cell and tissue damage), and the body’s stress hormone, cortisol. These factors negatively influence blood sugar levels in your body. According to the Sleep Foundation, just one night of poor sleep can increase insulin resistance.

Smoking

According to research published in the American Journal of Lifestyle Medicine, cigarette smoking, probably due to the effects of nicotine, increases your risk of insulin resistance—and the more you smoke, the greater your risk.

Gestational diabetes

Thanks to the hormonal changes and weight gain that happen during pregnancy, many women develop some degree of insulin resistance late in pregnancy. However, if you experienced insulin resistance before you conceived, your chance of developing full-blown gestational diabetes (diabetes while pregnant) is even higher.

Nonalcoholic fatty liver disease (NAFLD)

Insulin resistance can contribute to the development of NAFLD, a liver disease in which fat builds up in the liver. According to the NIDDK, NAFLD is more common in people who are overweight or obese or have other metabolic conditions, such as Type 2 diabetes.

Insulin resistance symptoms

Because the body does a fairly effective job—at least initially—of compensating for the cells’ decreased ability to absorb insulin, the symptoms of insulin resistance are often silent—until you’ve progressed to full-fledged diabetes. This underscores the importance of well visits with your physician and appropriate lab work. Central obesity, weight gain, elevated fasting blood sugars or hemoglobin A1c blood tests are easily diagnosed and a treatment plan can be instituted.

“Once you get into the diabetes phase, there are the three P’s that are typically present: polyuria (or an increase in urination), polydipsia (or increased thirst), and polyphagia, which can cause people to lose weight even though they’re eating more,” Dr. Reichert says. 

While insulin resistance may not necessarily produce outward symptoms, there are some red flags that indicate you may have the disorder. “Insulin resistance should be suspected in an individual if they have any three of the following five traits,” says Adil Alavi, MD, an endocrinologist with the Community Care Network These traits, which together are known as metabolic syndrome, include having:

• A large waist circumference
• Hypertension/high blood pressure (130/85 mmHg or you need to take medication for elevated blood pressure)
• High triglyceride levels (150 mg/dl or higher or you need to take medication to lower triglycerides). Triglycerides are a type of fat (lipid) found in your blood.
• Low levels of high-density lipoproteins (low HDL). HDL is known as the “good” cholesterol. Levels below 50 for women and below 40 for men (or if you’re taking medication to raise levels) are indicative of insulin resistance.
• High fasting blood sugar (over 100 mg/dl)

If you have any signs of diabetes, don’t hesitate to get urgent medical treatment. In addition to the three P’s mentioned above, other symptoms include:

• Blurry vision
• Numbness or tingling in your hands and feet
• Sores and cuts that heal slowly
• Feeling tired
• More infections than usual
• Very dry skin

Diagnosis

To diagnose insulin resistance your healthcare provider will ask about your family’s medical history and assess your weight and blood pressure. To come up with a definitive diagnosis, your doctor will usually order a blood test after you’ve fasted for eight or more hours (that’s because food can cause blood sugar spikes). This blood test—also called a fasting plasma glucose test—will measure how much glucose is in your blood. Anything higher than 100 mg/dl can signal insulin resistance or even prediabetes or diabetes itself. 

Your doctor may also want to test your cholesterol levels with the same blood sample, as insulin resistance is often associated with high cholesterol. While a specialist in endocrinology typically treat disorders like diabetes, your primary care physician can make the initial diagnosis and can often begin and manage diabetes treatment.

“Unaddressed insulin resistance can lead to the development of Type 2 diabetes as well as cardiovascular disease, such as heart attacks and stroke,” Dr. Alavi says. “The pancreatic beta cells, or the cells that produce insulin, work harder to try to compensate for the insulin resistance. However, eventually the beta cells fail sufficiently so that hyperglycemia [high blood sugar] and Type 2 diabetes develop. Increased free fatty acids can also contribute to more plaque formation in the coronary or carotid arteries, leading to heart attacks and strokes.”

How to reverse insulin resistance

Insulin resistance can be reversed—although some doctors prefer to use the word “controlled” or “managed”—and the most effective ways are with lifestyle changes.

• Eat a plant-based, insulin resistance diet rich in things like whole grains, beans, legumes, and vegetables. One study published in the European Journal of Epidemiology found that adhering to a plant-based diet, even after the researchers adjusted for things like body mass index (BMI) and certain lifestyle factors, lowered the risk of developing insulin resistance. “A vegetarian diet would be good,” Dr. Reichert states. “And a vegan diet is even better. And if you do want to eat meat, it definitely should be lean.”
• Lose weight if you need to. One study shows that even a modest weight loss of 10 pounds or so can reduce insulin resistance in overweight individuals. In related research, subjects in the NIH-funded Diabetes Prevention Program who lost just 5% to 7% of their starting weight reduced their risk of developing diabetes by 58%.
• Exercise. Research shows that one single bout of aerobic exercise can improve insulin resistance by 50% for up to 72 hours. Aim for the recommended 150 minutes of moderate-intensity physical activity per week. 
• Get adequate sleep. The CDC recommends at least seven hours a night for health and well-being.
• Quit smoking and/or vaping.

If, despite adopting a healthier lifestyle you still have insulin resistance, your healthcare provider will most likely prescribe medication. “There really are no Food and Drug Administration (FDA) approved drugs for use in treating insulin resistance, so we use diabetes drugs in an off-label use,” Dr. Lin says. Off-label drug use is a common and usually safe medical practice. It involves using a drug for a condition for which it is not FDA approved. 

Some of the drugs frequently prescribed for insulin resistance include:

• Metformin (glucophage). This drug helps sensitize the body to the insulin already made. It increases glucose uptake and decreases the amount of glucose that’s put out by the liver. “It’s been around a long time, is low cost, and is very well tolerated,” Dr. Lin notes. 
• Thiazolidinediones such as rosiglitazone (Avandia) and pioglitazone (Actos). These medications help mimic the insulin action in the body. Clinical trials show that these drugs help lower both fasting blood sugar levels and the blood sugar levels that may spike after a meal.
• Weight-loss drugs (Contrave, Qsymia, Phentermine, and others). By virtue of their ability to help a person lose weight, these medications can help improve insulin sensitivity. These drugs are often not covered by insurance, so you may have to pay out of pocket. Using a SingleCare coupon can help you get the best price for many of these medications as well as your other prescriptions.