Insulin resistance can start quietly, impact anyone and lead to diabetes if it goes unchecked. It’s also linked to a whole host of diseases, from Alzheimer’s to cancer.
“Insulin resistance is largely a silent condition,” NBC News medical reporter Dr. Akshay Syal, a board-certified internist at Atria Health & Research Institute in New York, tells TODAY.com.
“I think a lot of people get this mixed up: insulin resistance versus prediabetes versus Type 2 diabetes. There is, of course, a lot of overlap, but insulin resistance can happen without being pre-diabetic, without having diabetes.”
What Is Insulin Resistance?
Insulin is a hormone made by the body to help regulate blood sugar. When a person eats, the food is broken down into glucose, triggering the pancreas to release insulin, which “acts like a key” to allow the sugar to enter cells of the body and be used for energy, the Centers for Disease Control and Prevention notes.
Insulin resistance is when the body stops responding to the hormone as it normally does, Syal says.
“It sort of takes more insulin to get the job done,” he notes.
“What makes this different from diabetes or prediabetes is that in the early stages, you may not have an elevated blood sugar.”
That’s because the body initially makes more insulin to bring blood sugar levels back to normal, leading to hyperinsulinemia, so routine blood tests like hemoglobin A1C may not pick up any red flags. But eventually, the body can no longer compensate for the high blood sugar.
Insulin resistance “sets the stage” for prediabetes and Type 2 diabetes, the CDC warns.
Research also links it to cancer, Alzheimer’s disease and heart disease.
Experts have called insulin resistance “one of the major threats to global health in the 21st century.”
Who Is at Risk?
“Anybody can be at risk for this, but it’s really people who are obese, people with high amounts of visceral fat that we worry about the most,” Syal says.
Visceral fat is the type that wraps around the organs. Too much of it is linked to an increased risk of chronic disease.
People can be at normal weight and still have insulin resistance, the CDC notes.
It’s estimated about 40% of young adults in the U.S. have the condition, but almost half of them don’t have obesity, studies have found.
Insulin Resistance Symptoms
The condition doesn’t have a lot of warning signs, but Syal says there are a few hints he’d look for in his own body:
Dark Patches on Skin
These discolored areas, which can show up in skin folds such as the armpit or the back of the neck, are known as acanthosis nigricans. The darkened skin changes texture as well and becomes thicker and velvet-like. Syal calls this a classic sign.
“That is one thing that we do look for, especially when patients come into the exam room. It’s pretty obvious,” he says.
Skin Tags
This is another potential skin manifestation of insulin resistance.
Insulin is a “well-recognized growth-promoting hormone,” and excess levels of it in the blood may cause “endocrine disturbances” that change how cells grow and divide, which can lead to these small benign growths on the skin, studies have found.
Unexplained Weight Changes
A growing waistline can be a warning sign.
“Say you’re gaining a lot of weight, particularly around the abdomen or the belly, that would be a big one,” Syal notes.
“Nothing’s changed in your routine, and all of a sudden your weight starts fluctuating.”
Fatigue After Meals
People may feel very tired or heavy after eating, which is “usually not a good sign,” the doctor cautions.
How To Get Help
There’s no easily available gold standard test for insulin resistance, but testing insulin levels and fasting blood sugar can offer clues, Syal says. An A1C level that’s normal but trending upwards over time is another potential sign.
He tells patients who are worried about developing insulin resistance to try an over-the-counter continuous glucose monitor, which shows blood sugar levels in real time.
When the doctor wore the device himself, he noticed oatmeal spiked his blood sugar a little too high, so he cut down on his consumption of the breakfast staple.
A continuous glucose monitor can help people figure out which foods their body is sensitive to and see how walking after eating a meal stabilizes blood sugar, Syal notes.
“The downside is it can cause a lot of anxiety for people, and it’s not quite clear yet what those sugar spikes necessarily mean,” he says.
“It’s very important you show that data to your physician and somebody that you trust who can go over that with you to see if there might be signs that your body’s sugar is a little bit higher than it should be.”
How to Fight Insulin Resistance
It’s possible to reverse insulin resistance with exercise, weight loss and a healthy diet, the CDC notes.
Syal advises eating plenty of fiber, which helps with blood sugar control, and low-glycemic index foods that won’t spike blood sugar.
A healthy, active lifestyle is also key to prevention.
“Aerobic exercise is so, so important,” Syal says.
“You want to not eat too much sugar because if your blood sugar stays persistently high, eventually your body’s going to need to make more insulin to compensate, and that’s when we start to get to get worried.”
TODAY’s Symptom Check series features doctors, specialists and health experts who reveal the warning signs they’d look for in their own body when it comes to cancer and other diseases.