Cells throughout the body, including muscle and fat cells, need the hormone insulin to turn glucose (a form of sugar) into energy. In healthy people, insulin attaches to cells and “unlocks” them so glucose can get in. The glucose is used for energy or stored for later. But in people with insulin resistance, cells don’t respond properly to insulin—they “resist” it. As a result, cells stay “locked” and glucose builds up in the blood.
To bring the glucose level down, the body tells the pancreas to pump out more and more insulin. Over time, people with insulin resistance develop high levels of insulin in their blood.
Eventually the beta cells of the pancreas, which produce insulin, begin to wear out. If they can no longer make enough insulin to keep glucose levels in check, the result is prediabetes or type 2 diabetes.
History of Insulin Resistance
Insulin resistance is not new, although media attention to rising rates of obesity and prediabetes has raised awareness of the condition. It was first connected with diabetes in the 1930s by British physician Harold Percival Himsworth. He coined the term “insulin insensitivity” to describe patients who didn’t respond effectively to injected insulin. Himsworth’s work was the first to acknowledge the existence of two distinctly different types of diabetes—now known as type 1 and type 2.
Fifty years and much research later, Dr. Gerald Reaven described metabolic syndrome X, now known simply as metabolic syndrome. Many people with this condition have insulin resistance. They may have a large waist, high levels of blood fats known as triglycerides, low HDL (good) cholesterol levels, high blood pressure and/or high glucose levels. Metabolic syndrome raises the risk for type 2 diabetes and cardiovascular disease.
Making the Diagnosis
There is no single test your doctor can give you to diagnose insulin resistance. But according to the Centers for Disease Control and Prevention, if you have high glucose levels, high triglycerides, high LDL (“bad” cholesterol) and low HDL, your doctor may determine you have insulin resistance.
According to the National Institute of Diabetes and Digestive and Kidney Diseases, research has shown that if blood tests indicate prediabetes, insulin resistance most likely is present. Your doctor may screen you for prediabetes if you are overweight or obese (based on your Body Mass Index) and have one or more other risk factors for diabetes. You can find a BMI calculator at: https://www.nhlbi.nih.gov/health/educational/lose_wt/BMI/bmicalc.htm.
Risk factors for diabetes include:
- Being overweight or obese
- Being age 45 or older
- Being physically inactive
- Having a parent or sibling with diabetes
- Having a family background that is African American, Alaska Native, American Indian, Asian American, Hispanic/Latino, or Pacific Islander American
- Giving birth to a baby weighing more than 9 pounds
- Being diagnosed with gestational diabetes during pregnancy
- Having high blood pressure (140/90 mmHg or above) or being treated for high blood pressure
- HDL cholesterol below 35 mg/dL or triglycerides above 250 mg/dL
- Having polycystic ovary syndrome (PCOS)
- Having prediabetes, impaired fasting glucose, or impaired glucose tolerance on an earlier testing
- Having cardiovascular disease
What You Can Do
Reducing your carb intake, losing weight if necessary, getting more exercise, and getting enough sleep can help people with insulin resistance respond better to the hormone.