Insulin Resistance

Insulin resistance is a condition associated with type 2 diabetes. It happens when the body is unable to effectively use the insulin it makes in the pancreas. In type 2 diabetes, it is common for the pancreas to decrease the amount of insulin it makes. This results in increased blood glucose (blood sugar).1

What causes insulin resistance?

Being overweight or obese and lack of exercise are the major factors to developing insulin resistance. Other factors that play a role include:1

  • Race
  • Age
  • Problems affecting sleep
  • Smoking
  • The use of certain medicines

Excess body weight

Being overweight (having a body mass index [BMI] between 25 and 29.9) or obese (having a BMI of 30 or higher) is a key cause of insulin resistance.2

Increased waist size

A waist size of 40 inches or more in men or 35 inches or more in women increases the risk of insulin resistance. This risk happens even if your BMI is in the normal range.2

Fat tissue can trigger an immune response and chronic inflammation. Inflammation contributes to insulin resistance and can cause severe damage in the body over time, often without any symptoms. Fat may produce hormones and other chemicals that lead to insulin resistance. Fat can also cause other health problems, including heart disease, high blood pressure, and abnormal blood cholesterol.2

Inactivity

Decreased exercise may lead to insulin resistance and type 2 diabetes. The muscles of the body use more glucose (sugar) than any other type of tissue. After regular exercise, muscles have increased insulin sensitivity and can even absorb glucose without insulin. The more muscle mass the body has, the greater its ability to use glucose and keep blood glucose levels in the normal range.1,2

Sleep problems

The are several sleep issues that can affect insulin resistance:3,4

  • Quality and amount of sleep. The quality and total amount of sleep you get affects how your body responds to insulin. People who do not get the recommended amount of sleep or report poor-quality sleep have shown insulin resistance.
  • Hormone and chemical balance. Sleep problems can lead to an imbalance of hormones and chemicals in the body that help keep you feeling full or control your hunger. An imbalance leads to overeating, excess weight, and insulin resistance.
  • Changes to the circadian rhythm. An internal body clock in your brain controls circadian rhythms in your body. These rhythms rise and fall over the 24-hour day and help you fall asleep at night and wake up in the morning. Shift workers who work at night have changes to their circadian rhythms. Shift workers have a 44 percent increase in the risk of developing type 2 diabetes and insulin resistance changes.
  • Sleep disorders.Sleep apnea is a sleep disorder in which a person experiences pauses in breathing or shallow or infrequent breathing during sleep. This results in low quality of sleep and has been closely linked to the development of insulin resistance and type 2 diabetes.

Smoking

Chemicals from cigarettes damage the cells in your body. This affects their normal function and leads to inflammation. Smoking increases your risk of developing type 2 diabetes by 30 to 40 percent.5

Age and race

Normal aging leads to a decrease in muscle mass and strength. Decreased muscle mass causes a decrease in insulin uptake in the cells, leading to insulin resistance.6

Race may impact insulin resistance, though this relationship is still not well known. Some studies have shown that carrying weight around the stomach may increase the rate of insulin resistance in Black people. Other studies have found that Asian and Hispanic populations have an increased risk of obesity-related insulin resistance.7,8

Taking certain medicines

Some drugs may lead to insulin resistance over time. Steroids (glucocorticoids), some drugs for HIV, and some mental health drugs can cause this.1

Metabolic syndrome

Insulin resistance is closely related to metabolic syndrome (also called insulin resistance syndrome). To have metabolic syndrome, you must satisfy any 3 of the following criteria:2,9

  • Large waist size – A waist measurement of 35 inches or more for women and 40 inches or more for men.
  • Abnormally low levels of HDL cholesterol – Levels of high-density lipoprotein (HDL) cholesterol (known as the “good” cholesterol) below 50 mg/dL for women and 40 mg/dL for men, or taking medicine for low HDL cholesterol.
  • High triglycerides – Levels of triglycerides in the blood of 150 mg/dL or greater or taking medicine for high triglycerides.
  • High blood pressure – Blood pressure of 130/85 mmHg or greater or receiving treatment for high blood pressure.
  • Increased blood sugarFasting blood glucose measuring 100 mg/dL or greater or taking medicine for elevated blood glucose.

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Written by: Jonathan Simmons and Katie Murphy | Last reviewed: March 2021.