Insulin Resistance: Signs, Causes, Testing & What You Can Do

Insulin resistance happens when cells in your muscles, fat, and liver don't respond to insulin as effectively as they should. Your body may compensate by making more insulin to help keep blood sugar within a healthy range, which means insulin resistance can develop before you see abnormal blood sugar or A1C results.

The good news? Insulin sensitivity isn't fixed. Nutrition, movement, sleep, and other lifestyle habits can all play a role in improving how your body responds to insulin.

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What Is Insulin Resistance?

Insulin is a hormone made by your pancreas that helps regulate the amount of glucose, or sugar, in your blood. After you eat carbohydrates, they're broken down into glucose. As glucose enters your bloodstream, insulin helps your body's cells take up and use that glucose for energy.

With insulin resistance, cells in your muscles, fat, and liver don't respond to insulin as effectively. Your pancreas compensates by producing more insulin to help move glucose out of the bloodstream.

For a while, this can work quite well. Your blood sugar may stay within the normal range because your pancreas is producing enough insulin to compensate for your body's decreased insulin sensitivity.

Over time, however, the pancreas may have difficulty keeping up with the increased demand. Blood glucose can begin to rise, potentially progressing to prediabetes and eventually type 2 diabetes.

Simply put: Insulin resistance means your body needs more insulin than it once did to help manage blood sugar effectively.

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Insulin Resistance vs. Prediabetes

Insulin resistance and prediabetes are related, but they're not the same thing.

Insulin resistance describes how your body responds to insulin. Prediabetes, on the other hand, is defined by blood glucose levels that are higher than normal but not yet in the diabetes range.

Insulin Resistance	Prediabetes
Your cells don't respond to insulin as effectively	Blood glucose is above the normal range
Blood sugar may still be normal	Diagnosed using A1C, fasting glucose, or an oral glucose tolerance test
Can develop before prediabetes	Often occurs alongside insulin resistance
Not defined by one standard diagnostic blood test	Has established diagnostic criteria

For example, an A1C from 5.7% to 6.4% or a fasting blood glucose from 100 to 125 mg/dL falls within the prediabetes range.

This distinction is important because your body may compensate for insulin resistance by producing additional insulin for quite some time before blood glucose rises. For more on what those lab results mean, read my prediabetes guide.

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What Are the Signs of Insulin Resistance?

One of the frustrating things about insulin resistance is that it often doesn't have obvious symptoms. You may feel completely normal while changes in insulin sensitivity are happening behind the scenes.

Certain health conditions and clinical findings can, however, be associated with insulin resistance. These can include:

• Acanthosis nigricans, or areas of darkened, thickened skin, commonly around the neck or armpits
• Higher triglycerides or lower HDL cholesterol
• High blood pressure
• Increased abdominal or visceral fat
• Prediabetes or elevated blood glucose
• Polyendocrine Metabolic Ovarian Syndrome (PMOS)/Polycystic ovary syndrome (PCOS)
• Metabolic dysfunction-associated steatotic liver disease (MASLD)

This is also why symptoms like fatigue, cravings, brain fog, or feeling hungry shouldn't be used on their own to diagnose insulin resistance. Those symptoms can occur for many different reasons.

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What Causes Insulin Resistance?

There isn't one single cause of insulin resistance. Researchers are still studying exactly why some people develop it and others don't.

Several factors can influence insulin sensitivity and the likelihood of developing insulin resistance, including:

• Genetics and family history
• Physical inactivity
• Excess body fat, particularly visceral fat stored around the abdominal organs
• Aging
• Certain hormonal and metabolic conditions
• PMOS/PCOS
• Some medications
• Sleep and circadian disruption

Having one or more risk factors doesn't mean you will develop insulin resistance. Likewise, insulin resistance isn't limited to people in larger bodies. Someone can be at a weight considered "normal" and still have insulin resistance.

Rather than focusing on one factor, it can be more helpful to look at your overall metabolic health, family history, lifestyle, and laboratory results with your healthcare provider.

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How Is Insulin Resistance Diagnosed?

This is where things get a little more complicated.

There isn't one standard test routinely used in clinical practice to diagnose insulin resistance. In fact, direct testing for insulin resistance is primarily used in research settings.

Instead, your healthcare provider may look at your medical history, risk factors, physical findings, and blood tests to get a broader picture of your metabolic health.

Common tests may include:

A1C: Estimates your average blood glucose over approximately the previous three months. An A1C below 5.7% is considered normal, 5.7% to 6.4% falls within the prediabetes range, and 6.5% or higher meets the diagnostic threshold for diabetes.

Fasting plasma glucose: Measures your blood glucose after fasting. A fasting glucose of 100 to 125 mg/dL is within the prediabetes range, while 126 mg/dL or higher meets the diabetes threshold.

Oral glucose tolerance test (OGTT): Measures how your body handles a specific amount of glucose over time. A two-hour glucose result of 140 to 199 mg/dL falls within the prediabetes range.

You may also hear about fasting insulin or calculations such as HOMA-IR, which use fasting insulin and glucose to estimate insulin resistance. These can provide additional information in some situations, but there isn't a universally accepted cutoff for diagnosing insulin resistance in routine clinical practice.

Other markers, including triglycerides, HDL cholesterol, blood pressure, waist circumference, and liver health, may also help provide context.

Can You Have Insulin Resistance With a Normal A1C?

Yes.

Remember, early in insulin resistance your pancreas may compensate by producing more insulin. That additional insulin may be enough to keep blood glucose within the normal range.

Because A1C reflects blood glucose rather than insulin levels, a normal A1C doesn't necessarily tell you how hard your body is working to maintain that glucose level.

This doesn't mean everyone with a normal A1C needs insulin testing. Your healthcare provider can help determine which tests make sense based on your health history and individual risk factors.

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Can Insulin Resistance Be Reversed?

You'll often hear people talk about "reversing" insulin resistance. A more precise way to think about it is that insulin sensitivity can improve.

Insulin resistance isn't necessarily a permanent state. Changes in physical activity, nutrition, body composition, sleep, and other factors can improve how effectively your cells respond to insulin.

For people with prediabetes and overweight or obesity, lifestyle interventions that include regular physical activity and modest weight loss have been shown to significantly reduce the risk of progressing to type 2 diabetes. But weight loss isn't the only measure of progress. Physical activity itself can improve insulin sensitivity and metabolic health, even when the number on the scale doesn't change much.

The goal isn't to achieve a perfect insulin response. It's to improve metabolic health and reduce your long-term risk.

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How to Improve Insulin Sensitivity

There isn't one food, supplement, or blood sugar "hack" that fixes insulin resistance. The habits with the strongest evidence are usually much less exciting, but they're also much more sustainable.

Build Balanced Meals

You don't need to eliminate carbohydrates to improve insulin sensitivity. My guide to slow carbs explains how carbohydrate quality and fiber fit into the bigger picture.

Instead, consider what you're eating with your carbohydrates. Pairing carbohydrate foods with sources of protein, fiber, and healthy fats can create more balanced meals while providing nutrients that support overall metabolic health.

A simple place to start is to build meals around:

• Carbohydrate: whole grains, fruit, beans, potatoes, dairy, or another carbohydrate you enjoy
• Protein: eggs, Greek yogurt, cottage cheese, poultry, fish, tofu, beans, or lean meats
• Fiber: vegetables, fruit, beans, lentils, nuts, seeds, or whole grains
• Healthy fat: nuts, seeds, avocado, olive oil, nut butter, or fatty fish

You don't need all four categories represented perfectly at every meal. Think of this as a flexible framework rather than another set of food rules. Use my portion size guide to build a satisfying plate, and my healthy snacking formula when you need something between meals.

Optional resources for busy days: For meal inspiration, browse my diabetes cookbook on Amazon (affiliate link). If preparing food ahead helps, glass meal-prep containers (affiliate link) are an optional tool for storing ingredients and leftovers. Use containers you already have, too.

Move Your Body Regularly

Physical activity helps your muscles use glucose and can improve insulin sensitivity. Current recommendations for diabetes prevention emphasize working toward at least 150 minutes of moderate-intensity activity per week.

That doesn't have to mean spending hours at the gym. Walking, cycling, swimming, dancing, hiking, recreational sports, and many other activities count.

And if 150 minutes feels far from where you are now, start smaller. Ten minutes still counts.

Take a Walk After Meals

You don't have to save all your movement for a formal workout.

Breaking up long periods of sitting and adding movement after meals can help reduce post-meal blood glucose. Even a short walk after dinner can be a practical habit to build into everyday life.

Include Strength Training

Your muscles are an important site for glucose disposal, making resistance exercise another useful tool for metabolic health.

Strength training doesn't have to mean heavy barbells or complicated workouts. Dumbbells, resistance bands, weight machines, or body-weight exercises can all count.

Aim for consistency rather than trying to create the "perfect" workout routine.

Prioritize Sleep

Sleep is easy to overlook when talking about blood sugar, but metabolic health isn't only about food and exercise.

Insufficient or disrupted sleep can affect glucose metabolism and insulin sensitivity. A consistent sleep schedule and getting adequate sleep when possible can be another piece of the bigger picture.

Focus on Habits You Can Maintain

It's easy to respond to concerns about blood sugar by trying to change everything at once: eliminate sugar, cut carbohydrates, exercise every day, lose weight, take multiple supplements, and somehow sleep perfectly.

You don't need to do all of that.

Choose one or two habits that fit your actual life and work on doing them consistently. Once those feel routine, you can build from there.

Real-Life Blood Sugar Balance

You don't need to eliminate carbs, exercise every day, or overhaul your entire life to support insulin sensitivity.

Start with one habit you can repeat consistently, such as adding protein to breakfast, taking a 10-minute walk after dinner, or strength training twice a week.

Real-life blood sugar balance > perfection.

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Frequently Asked Questions

Can you have insulin resistance without prediabetes?

Yes. Your pancreas may initially compensate for insulin resistance by producing more insulin, allowing blood glucose to remain within the normal range. Prediabetes develops when blood glucose rises above the normal range but hasn't reached the threshold for diabetes.

Does insulin resistance mean you'll develop type 2 diabetes?

No. Insulin resistance increases the risk of developing prediabetes and type 2 diabetes, but progression isn't inevitable. Lifestyle changes and, when appropriate, medical treatment can improve metabolic health and reduce diabetes risk.

Can you have insulin resistance if you're thin?

Yes. Body size alone can't tell you whether someone has insulin resistance. Genetics, family history, body-fat distribution, physical activity, age, medical conditions, medications, and other factors can all influence insulin sensitivity.

How long does it take to improve insulin resistance?

There isn't one timeline that applies to everyone. Changes in insulin sensitivity can occur with physical activity relatively quickly, while measurable changes in A1C, body composition, and other metabolic markers may take longer. What matters most is building habits you can maintain over time.

Should you stop eating carbohydrates if you have insulin resistance?

No. Having insulin resistance doesn't mean you need to eliminate carbohydrates. Carbohydrate quality, portion, what you pair carbohydrates with, your overall eating pattern, and your activity level all matter.

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The Takeaway

Insulin resistance isn't an all-or-nothing state, and learning that you may be at risk doesn't mean you need to completely overhaul your diet.

Improving insulin sensitivity often comes back to fairly unglamorous basics: balanced meals, regular movement, strength training, adequate sleep, and habits you can actually maintain. Rather than chasing every new blood sugar hack, choose one or two changes you can consistently repeat.

That's what real-life blood sugar balance is all about.

If you are sorting through conflicting food advice, start with Does Sugar Cause Diabetes? and how carbohydrates relate to type 2 diabetes risk. Both put individual foods into the broader prevention picture.

This article provides general education for adults and does not replace individualized medical care. Work with your healthcare team on testing, treatment, and a plan that fits your needs.

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Sources

1. National Institute of Diabetes and Digestive and Kidney Diseases. Insulin Resistance & Prediabetes.
2. American Diabetes Association. Standards of Care in Diabetes—2026: Diagnosis and Classification of Diabetes.
3. American Diabetes Association. Standards of Care in Diabetes—2026: Prevention or Delay of Diabetes and Associated Comorbidities.
4. Centers for Disease Control and Prevention. A1C Test for Diabetes and Prediabetes.
5. National Institute of Diabetes and Digestive and Kidney Diseases. Diabetes Tests & Diagnosis.