Insulin, a hormone that the pancreas makes, allows cells to absorb and use glucose. In people with insulin resistance, the cells are unable to use insulin effectively.

When the cells cannot absorb glucose, or blood sugar, its levels build up in the blood. If glucose levels are higher than usual but not high enough to indicate diabetes, doctors call this prediabetes.

Prediabetes often occurs in people with high insulin resistance. Around 1 in 3 people in the United States have prediabetes, according to figures from the Centers for Disease Control and Prevention (CDC).

In this article, we look at the current understanding of insulin resistance and its role as a risk factor for diabetes and other conditions. We also describe the signs and symptoms of insulin resistance and ways to avoid it.

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Insulin resistance occurs when excess glucose in the blood reduces the ability of the cells to absorb and use blood sugar for energy.

This increases the risk of developing prediabetes and, eventually, type 2 diabetes.

If the pancreas can make enough insulin to overcome the low rate of absorption, diabetes is less likely to develop, and blood glucose will stay within a healthy range.

How does insulin resistance lead to diabetes?

In a person with prediabetes, the pancreas works increasingly hard to release enough insulin to overcome the body’s resistance and keep blood sugar levels down.

Over time, the pancreas loses its ability to release insulin, and this can lead to the development of type 2 diabetes.

Insulin resistance remains a major feature of type 2 diabetes.

Insulin regulates the amount of glucose that circulates in the bloodstream. It induces the cells to absorb glucose, which comes from the food people eat.

Insulin is also the chemical messenger that instructs the liver to store some glucose, rather than release it into the bloodstream. The liver packages glucose for storage in the form of glycogen.

Insulin usually helps the body maintain a good balance of energy, not allowing the level of blood glucose to spike for too long.

The reasons for insulin resistance remain complex, and researchers continue to investigate.

The following steps outline the current understanding of how insulin resistance develops:

  1. Insulin loses its ability to support body cells effectively.
  2. At first, the pancreas secretes more insulin in order to maintain safe blood sugar levels.
  3. The pancreas becomes unable to maintain the release of extra insulin to compensate for the cells’ increasing resistance.
  4. Consistently high levels of blood glucose develop, which can lead to prediabetes and type 2 diabetes if an individual is unable to receive treatment and manage blood sugar levels.

Insulin resistance does not usually present symptoms until diabetes develops. The CDC reports that over 85% of people with prediabetes are probably unaware that they have the condition.

There are also links between insulin resistance and the following health issues:

If someone has concerns about these conditions, they may wish to consider seeking a test for insulin levels and insulin resistance.

The following are risk factors for insulin resistance, prediabetes, and diabetes:

Prediabetes and diabetes have some risk factors in common with heart disease and other cardiovascular and cerebrovascular health problems, such as stroke.

It is not always possible to prevent these risk factors, but some may be avoidable. For this reason, doctors encourage lifestyle measures that can help reduce the risk of the condition.

The Department of Health and Human Services recommends that everyone over 45 years of age receive testing for diabetes.

It also recommends testing before the age of 45 if a person:

  • has overweight or obesity
  • has high cholesterol levels
  • has a family history of diabetes
  • is of African American, Asian American, Latino or Hispanic American, Native American, or Pacific Islander descent
  • has had gestational diabetes or delivered a baby weighing over 9 pounds

Learn why diabetes is more likely to affect African Americans here.

A number of tests can help diagnose prediabetes and diabetes:

  • A1C test: This measures a person’s average blood sugar level over the previous 3 months.
  • Fasting blood glucose test: A doctor checks glucose levels after an individual refrains from eating or drinking for 8 or more hours.
  • Random glucose test: This involves a medical professional checking blood glucose levels at some point during the day.

Doctors usually request more than one of these tests to ensure an accurate diagnosis.

If blood sugar levels consistently fall outside of a normal range, it might indicate that the body is becoming resistant to insulin.

It is not possible to change some risk factors for insulin resistance and type 2 diabetes, such as genetic factors and family history.

However, a person can take some steps to reduce the likelihood of developing insulin resistance.

Some of the same strategies, such as managing weight or quitting smoking, are key to preventing heart disease and stroke. Experts say that up to 50% of people with prediabetes can prevent the onset of diabetes through such measures.

According to the CDC, if a person with overweight or obesity loses 5–7% of their body weight, this can significantly reduce their risk of developing diabetes.

Exercise can also help. Muscles become more sensitive to insulin after exercise, helping the body reverse insulin resistance.

A diagnosis of insulin resistance can be worrying, but it is not necessarily too late to prevent diabetes.

Learn about the best foods to eat and avoid to reverse prediabetes here.

Insulin resistance is a feature of type 2 diabetes, and it can be present with prediabetes.

Insulin is essential for enabling the body to use glucose effectively and prevent blood sugar levels from rising too high. When insulin does not work effectively, blood sugar levels can rise, and diabetes can develop.

Many people with prediabetes can prevent type 2 diabetes from developing by taking lifestyle measures to counter insulin resistance and the development of diabetes early on.

Read this article in Spanish.