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What is Insulin Resistance? Testing, Causes, Prevention & More

Written by: AgaMatrix
What is Insulin Resistance? Testing, Causes, Prevention & More

Insulin resistance does not often show signs or symptoms, but it can lead to serious health concerns such as prediabetes or type 2 diabetes. Insulin resistance tests are necessary for diagnoses, but understanding the risk factors, treatment, and prevention can help you prepare to consult with your healthcare team.

Read on to learn:

What is Insulin?

When your glucose levels increase — like after you eat or drink — your pancreas responds by releasing a hormone called insulin.

Insulin’s job is to help glucose enter your cells so that it can be converted into energy. Once glucose levels start to decrease in your bloodstream, your pancreas receives a signal to decrease the amount of insulin it’s releasing.

Here’s how insulin works, according to the Centers for Disease Control and Prevention (CDC):

  1. When you eat, food is broken down into glucose and enters your bloodstream.
  2. Your pancreas receives a signal to release insulin.
  3. Insulin’s job is to help glucose enter your cells so that it can be transferred into energy. It also tells your liver to store glucose for later use, much like a backup repository.
  4. Once glucose enters your cells, the levels in your bloodstream decrease. This tells your pancreas to decrease the amount of insulin it’s releasing.
  5. If your insulin levels decrease, your liver is in charge of releasing the glucose it stored earlier. This gives you continuous energy, even in between meals.

What is Insulin Resistance?

Insulin resistance, also known as impaired insulin sensitivity, occurs when your cells have difficulty responding to the hormone. When this happens, the step-by-step process listed above can go askew and an insulin resistance test is necessary to detect it.

If your cells develop an impaired response to insulin, your body may try to compensate by making more insulin. If your pancreas is able to make enough extra insulin to help glucose enter your cells, glucose levels may stay in check. However, if your pancreas is unable to make enough insulin to keep up with demand, then it can cause:

  • An abundance of glucose in your bloodstream.
  • Cells to become insulin resistant.
  • Prediabetes or the development of type 2 diabetes.

The Types of Insulin Resistance Tests

Insulin resistance is not something that is commonly tested for. However, if prediabetes or type 2 diabetes is suspected, a doctor will perform an insulin resistance test.

The most commonly used insulin resistance tests are:

Fasting plasma glucose test (FPG)

An FPG test is used to diagnose prediabetes and diabetes by testing a person’s blood sugar level after they have not eaten for 8 to 12 hours — usually overnight. When you have an annual physical, the standard blood panel includes an FPG test, which makes it the most common type of insulin resistance test.

Oral glucose tolerance test (OGTT)

An OGTT is performed after an overnight fast. A healthcare professional starts by taking a blood sample, and then you are instructed to drink a high-glucose beverage. Additional blood samples are taken at specific intervals for two to three hours, and the results are compared to analyze how your body processes glucose over time. This test is not used as often as others.

Random blood glucose test (RBG)

An RBG test measures your blood sugar at any time throughout the day, without the need for fasting. This test is performed when a quick diagnosis is necessary.

A1C test

The A1C test — also known as a hemoglobin A1C, HbA1c, or glycosylated hemoglobin test — measures a person’s average blood sugar level from the past two to three months. According to the American Diabetes Association (ADA), hemoglobin is a protein in red blood cells that carries oxygen to cells. Glucose and hemoglobin can join together in the bloodstream, and the A1C test measures the percentage of hemoglobin that is coated with glucose.

The CDC classifies the following results for each blood test:

Result A1C FPG RBG Glucose Tolerance
Diabetes 6.5% or higher 126 mg/dL or higher 200 mg/dL or higher 200 mg/dL or higher
Prediabetes 5.7% – 6.4% 100-125 mg/dL n/a 140-199 mg/dL
Normal Range Under 5.7% Under 100 mg/dL n/a Under 140 mg/dL

For gestational diabetes, a glucose screening test — commonly referred to as the one-hour or O’Sullivan one-hour glucose tolerance test — will be administered to pregnant women between weeks 24 to 28. If this test shows high blood glucose, you will need an OGTT. The target ranges for gestational diabetes are lower than the ranges in the above table.

If you are diagnosed with prediabetes, the ADA recommends being checked for type 2 diabetes every 1-2 years.

Endocrine Issues Caused by Insulin Resistance

The CDC reports that an excess amount of glucose in the bloodstream can be very damaging to the body. This can also lead to an increase in insulin, which signals to the liver and muscles that they should start storing glucose. The liver sends excess glucose to fat cells, which can lead to weight gain. At this stage, the body’s impaired insulin response sets the foundation for other health concerns to possibly develop.

Your healthcare team may order an insulin resistance test to check for the following:

Prediabetes

Prediabetes is considered a precursor for type 2 diabetes, where glucose levels are elevated above normal but not considered high enough for a diabetes diagnosis. Prediabetes develops in people who already have a resistance to insulin and also increases your risk of type 2 diabetes, cardiovascular disease, and stroke.

According to the CDC, about 84 million American adults have prediabetes — that’s more than 1 in 3 people. Of those 84 million, 90% don’t know they have it, primarily because prediabetes does not often present noticeable symptoms, sometimes for years. Just because you may have prediabetes does not mean you will develop type 2 diabetes.

Type 2 Diabetes

Type 2 diabetes develops from prediabetes, as insulin resistance is sustained. It is caused by your body’s inability to use or make enough insulin, which means you can no longer maintain a normal blood glucose level. Type 2 diabetes is the more common form of diabetes, compared to type 1 diabetes where a person’s pancreas is unable to produce any insulin due to an autoimmune-related condition.

Type 2 diabetes often develops over years, but some people can manage their glucose levels through diet and lifestyle changes, preventing or delaying the need for glucose-lowering medications. There are also other contributing factors to developing type 2 diabetes, including genetics, activity levels, and weight.

The CDC states that more than 30 million Americans have diabetes and that 90-95% of them have type 2 diabetes. Most commonly, type 2 diabetes develops in people over the age of 45. However, the number of children, teenagers, and young adults who develop type 2 diabetes has been increasing in recent years.

Gestational Diabetes

Pregnant women can be susceptible to gestational diabetes. According to the CDC, 2-10% of pregnancies in the U.S. are affected by gestational diabetes every year. This type of diabetes usually develops around the 24th week of pregnancy with doctors testing for it between 24 and 28 weeks.

Gestational diabetes develops due to the substantial changes a woman’s body undergoes during pregnancy, including an increase in hormone production and weight gain. Because of these changes, the body can have difficulty using insulin effectively and the woman can develop insulin resistance.

Who Should Be Tested for Insulin Resistance?

Insulin resistance tests may be ordered for people with certain genetic and lifestyle risk factors. According to the National Institute of Diabetes and Digestive and Kidney Diseases (NIDDK), the following factors can make people more likely to develop insulin resistance and possibly prediabetes:

  • Being overweight or obese.
  • Being 45 or older.
  • Having a history of polycystic ovary syndrome (PCOS), gestational diabetes, heart disease, or stroke.
  • Health issues like high blood pressure and/or abnormal cholesterol levels.
  • Physical inactivity.
  • A history of diabetes in the immediate family.
  • Ethnicities such as African American, Alaska Native, American Indian, Asian American, Hispanic/Latino, Native Hawaiian, or Pacific Islander American.
  • Hormonal disorders like Cushing’s syndrome or acromegaly.
  • Taking certain medications like glucocorticoids, certain antipsychotics, and certain HIV medications.
  • Sleep problems, such as sleep apnea.

The NIDDK also notes that excess fat in the abdomen and around the organs can be a cause of insulin resistance. “A waist measurement of 40 inches or more for men and 35 inches or more for women is linked to insulin resistance,” even if their body mass index (BMI) is within a normal range.

If weight loss goals are not currently a realistic option, there are still ways to improve your blood sugar levels through diet and activity. Consult with your doctor to learn about the best options for your health.

Symptoms of Insulin Resistance

Insulin resistance typically doesn’t show any symptoms until it becomes prediabetes or type 2 diabetes. However, some people with severe insulin resistance can develop acanthosis nigricans, which is darkened skin that can appear on the armpit or the back or side of the neck.

Your doctor may test you for prediabetes if you have any of the previously mentioned risk factors. If you are tested and your results are normal, your doctor will likely retest you every few years.

Preventing & Treating Insulin Resistance

The NIDDK notes that a lack of physical activity can be linked to insulin resistance and prediabetes. The Diabetes Prevention Program (DPP), a National Institutes of Health-funded research study, found that people who are at a high risk of developing diabetes could reduce this risk by losing 5% to 7% of their weight through physical activity and a change in diet.

A Registered Dietitian Nutritionist (RDN) can work with you to create an individualized meal plan to help lower insulin resistance. The meal plan can take into consideration your food preferences, work schedule, weight, health goals, and more. Medicare and most insurance plans cover visits with an RDN. Ask your healthcare professional for a referral, or visit eatright.org to find a dietitian near you.

If your healthcare team recommends increasing physical activity and losing weight, adding a mild-moderate exercise to your routine may help your body improve how it balances blood glucose levels and responds to insulin. Your healthcare team may also recommend a move toward eating healthier to help you lose weight, reverse insulin resistance, and prevent or delay the onset of type 2 diabetes if you currently have prediabetes.

The DPP also reports that taking metformin, a medicine used to treat diabetes, can delay the onset of diabetes. Metformin was found to work best for younger adults, people with obesity, and women with a history of gestational diabetes.

The right treatment for insulin resistance is different for everyone. If you’re concerned about insulin resistance or have further questions about your health, you should consult with your doctor to inquire about an insulin resistance test and to receive individualized recommendations. Also, remember to check with a medical professional before making any significant lifestyle changes.

24 Snack Ideas for Insulin Resistance
Free tip sheet with 24 insulin resistance diet snacks containing 15 grams of carbohydrate or less.
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AgaMatrix
Written by: AgaMatrix

We are a diverse, driven, team of engineers, scientists, designers, and professionals across three continents who are passionate about providing technology that shapes the future of diabetes care. We are friends of the diabetes community, inventors of the first blood glucose meter to directly connect to the iPhone, and developers of unique glucose monitoring and connected health solutions.

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