Insulin Resistance Causes and Symptoms
One in three Americans—including half of those age 60 and older1— have a silent blood sugar problem known as insulin resistance. Insulin resistance increases the risk for prediabetes, type 2 diabetes and a host of other serious health problems, including heart attacks, strokes2 and cancer.3
What is Insulin Resistance?
Insulin resistance is when cells in your muscles, body fat and liver start resisting or ignoring the signal that the hormone insulin is trying to send out—which is to grab glucose out of the bloodstream and put it into our cells. Glucose, also known as blood sugar, is the body’s main source of fuel. We get glucose from grains, fruit, vegetables, dairy products, and drinks that bring break down into carbohydrates.
How Insulin Resistance Develops
While genetics, aging and ethnicity play roles in developing insulin sensitivity, the driving forces behind insulin resistance include excess body weight, too much belly fat, a lack of exercise, smoking, and even skimping on sleep.4
As insulin resistance develops, your body fights back by producing more insulin. Over months and years, the beta cells in your pancreas that are working so hard to make insulin get worn out and can no longer keep pace with the demand for more and more insulin. Then – years after insulin resistance silently began – your blood sugar may begin to rise and you may develop prediabetes or type 2 diabetes. You may also develop non-alcoholic fatty liver disease (NAFLD), a growing problem associated with insulin resistance that boosts your risk for liver damage and heart disease. 5
Signs and Symptoms of Insulin Resistance
Insulin resistance is usually triggered by a combination of factors linked to weight, age, genetics, being sedentary and smoking.
- A large waist. Experts say the best way to tell whether you’re at risk for insulin resistance involves a tape measure and moment of truth in front of the bathroom mirror. A waist that measures 35 inches or more for women, 40 or more for men (31.5 inches for women and 35.5 inches for men if you’re of Southeast Asian, Chinese or Japanese descent)6 increases the odds of insulin resistance and metabolic syndrome, which is also linked to insulin resistance.
- You have additional signs of metabolic syndrome. According to the National Institutes of Health,7 in addition to a large waist, if you have three or more of the following, you likely have metabolic syndrome, which creates insulin resistance.
- High triglycerides. Levels of 150 or higher, or taking medication to treat high levels of these blood fats.
- Low HDLs. Low-density lipoprotein levels below 50 for women and 40 for men – or taking medication to raise low high-density lipoprotein (HDL) levels.
- High blood pressure. Readings of 130/85 mmHg or higher, or taking medication to control high blood pressure
- High blood sugar. Levels of 100-125 mg/dl (the prediabetes range) or over 125 (diabetes).
- High fasting blood sugar (or you're on medicine to treat high blood sugar). Mildly high blood sugar may be an early sign of diabetes.
- You develop dark skin patches. If insulin resistance is severe, you may have visible skin changes. These include patches of darkened skin on the back of your neck or on your elbows, knees, knuckles or armpits. This discoloration is called acanthosis nigricans.8
Health Conditions Related to Insulin Resistance
An estimated 87 million American adults have prediabetes; 30-50% will go on to develop full-blown type 2 diabetes. In addition, up to 80% of people with type 2 diabetes have NAFLD.9 But those aren’t the only threats posed by insulin resistance.
Thanks to years of high insulin levels followed by an onslaught of cell-damaging high blood sugar, people with insulin resistance, prediabetes and type 2 diabetes are at high risk for cardiovascular disease. Insulin resistance doubles your risk for heart attack and stroke – and triples the odds that your heart attack or ‘brain attack’ will be deadly, according to the International Diabetes Federation.10
Meanwhile, insulin resistance and metabolic syndrome are also linked with higher risk for cancers of the bladder, breast, colon, cervix, pancreas, prostate and uterus.11, 12 The connection: High insulin levels early in insulin resistance seem to fuel the growth of tumors and to suppress the body’s ability to protect itself by killing off malignant cells. 13
How You Can Prevent or Reverse Insulin Resistance
Losing weight, getting regular exercise and not skimping on sleep can all help improve your insulin sensitivity. Don’t rely on dieting or exercise alone: in one fascinating University of New Mexico School of Medicine study, published in the International Journal of Obesity, overweight people who lost 10% of their weight through diet plus exercise saw insulin sensitivity improve by an impressive 80%. Those who lost the same amount of weight through diet alone got a 38% increase. And those who simply got more exercise, but didn’t lose much weight, saw almost no shift in their level of insulin resistance.14
Turn in on time, too. In a study presented at the 2015 meeting of the Obesity Society, researchers found that just one night of sleep deprivation boosted insulin resistance as much as eating high-fat foods for six months.15