Insulin is a hormone made by the pancreas that helps glucose in your blood enter cells in your muscle, fat, and liver, where it’s used for energy. Glucose comes from the food you eat. The liver also makes glucose in times of need, such as when you’re fasting. When blood glucose, also called blood sugar, levels rise after you eat, your pancreas releases insulin into the blood. Insulin then lowers blood glucose to keep it in the normal range.
Insulin resistance is when cells in muscles, fat, and liver don’t respond well to insulin and can’t use glucose from blood for energy. To make up for it, pancreas makes more insulin. Over time, blood sugar levels go up. Insulin resistance syndrome includes a group of problems like obesity, high blood pressure, high cholesterol, and type 2 diabetes. It could affect as many as 1 in 3 Americans. You might also hear it called metabolic syndrome.
Prediabetes means your blood glucose levels are higher than normal but not high enough to be diagnosed as diabetes. Prediabetes usually occurs in people who already have some insulin resistance or whose beta cells in the pancreas aren’t making enough insulin to keep blood glucose in the normal range. Without enough insulin, extra glucose stays in your bloodstream rather than entering your cells. Over time, you could develop type 2 diabetes.
Symptoms of Insulin Resistance
You can’t tell that you have insulin resistance by how you feel. You’ll need to get a blood test that checks your blood sugar levels. Likewise, you won’t know if you have most of the other conditions that are part of insulin resistance syndrome (high blood pressure, low “good” cholesterol levels, and high triglycerides) without seeing your doctor.
Some signs of insulin resistance include:
- A waistline over 40 inches in men and 35 inches in women
- Blood pressure readings of 130/80 or higher
- A fasting glucose level over 100 mg/dL
- A fasting triglyceride level over 150 mg/dL
- A HDL cholesterol level under 40 mg/dL in men and 50 mg/dL in women
- Skin tags
- Patches of dark, velvety skin called acanthosis nigricans
Risk Factors and Causes of Insulin Resistance
Things that can make this condition more likely include:
- Obesity, especially belly fat
- Inactive lifestyle
- Diet high in carbohydrates
- Gestational diabetes
- Health conditions like nonalcoholic fatty liver disease and polycystic ovary syndrome
- A family history of diabetes
- Ethnicity — it’s more likely if your ancestry is African, Latino, or Native American
- Age — it’s more likely after 45
- Hormonal disorders like Cushing’s syndrome and acromegaly
- Medications like steroids, antipsychotics, and HIV medications
- Sleep problems like sleep apnea
Diagnosis and Tests for Insulin Resistance
Your doctor will use these things to diagnose insulin resistance:
- Questions. They’ll want to know about your family’s medical history.
- Physical exam. They’ll weigh you and check your blood pressure.
- Blood tests. You might get:
Fasting plasma glucose test. This test measures your blood sugar after you haven’t eaten for at least 8 hours.
Oral glucose tolerance test. First, you’ll take the fasting glucose test. Then you’ll drink a sugary solution. Two hours after that, you’ll take another blood test.
Hemoglobin A1c test. This blood test shows your average blood sugar level for the past 2 to 3 months. Doctors use it to diagnose prediabetes or diabetes. If you have diabetes, it helps show whether it’s under control. You may need to take the test again to confirm the results.
How Insulin Resistance Progresses to Type 2 Diabetes
When you have insulin resistance, your pancreas makes extra insulin to make up for it. For a while, this will work and your blood sugar levels will stay normal.
Over time, though, your pancreas won’t be able to keep up. If you don’t make changes in the way you eat and exercise, your blood sugar levels will rise until you have prediabetes. Your doctor will look for these blood test results:
- Fasting plasma glucose test: 100-125
- Oral glucose tolerance test: 140-199 after the second test
- A1c results of 5.7% to 6.4%
If you aren’t able to manage prediabetes, you’ll be diagnosed with type 2 diabetes when your test levels reach:
- Fasting plasma glucose test: 126 or higher
- Oral glucose tolerance test: 200 or higher after the second test
- A1c results of 6.5% or above
Insulin Resistance Treatment and Prevention
You can take steps to reverse insulin resistance and prevent type 2 diabetes:
- Exercise. Go for at least 30 minutes a day of moderate activity (like brisk walking) 5 or more days a week. If you’re not active now, work up to that.
- Get to a healthy weight. If you’re not sure what you should weigh or how to reach a weight loss goal, ask your doctor. You may also want to talk with a nutritionist and a certified personal trainer.
- Eat a healthy diet. Think fruits, vegetables, whole grains, nuts, beans, fish, legumes, and other lean protein.
- Take medications. Your doctor may prescribe a medication called metformin (Fortamet, Glucophage, Glumetza, Riomet) to help keep your blood sugar in check.
Complications of Insulin Resistance
If metabolic syndrome goes untreated, it could lead to:
- Severe high blood sugar
- Severe low blood sugar
- Heart attack
- Kidney disease
- Eye problems
- Alzheimer’s disease