What Is Insulin Resistance?
Why Your Blood Sugar Can Look Normal While Your Body Is Working Harder to Control It
HEALTH
Coach Marcus Jones
8/20/202614 min read
What Is Insulin Resistance?
Why Your Blood Sugar Can Look Normal While Your Body Is Working Harder to Control It
By Coach Marcus Jones
When most people think about blood sugar, they think about diabetes.
Your blood sugar is high.
You get diagnosed with diabetes.
Then you start paying attention.
But metabolic health isn't always that simple.
Changes can begin long before someone is diagnosed with type 2 diabetes.
One of the most important changes to understand is:
INSULIN RESISTANCE.
You've probably heard the term.
Maybe someone told you insulin resistance makes it harder to lose weight.
Maybe you've heard it connected with belly fat.
Pre-diabetes.
Fatty liver.
High triglycerides.
Or type 2 diabetes.
Some of those connections are real.
But insulin resistance has also become another wellness term that gets blamed for almost everything.
So let's simplify it.
Insulin is a hormone your body needs.
Insulin resistance occurs when certain tissues don't respond to insulin as effectively as they normally should.
Your pancreas may compensate by producing more insulin.
For a while, that compensation can help keep your blood glucose within a relatively normal range.
That's one reason insulin resistance can be developing without someone realizing it.
Today we're going to talk about what that means, why it matters after 50, and what you can actually do about it.
IN THIS ARTICLE
What insulin is
What insulin does
What insulin resistance means
How your pancreas compensates
Why blood sugar can initially remain normal
Insulin resistance vs. prediabetes
Insulin resistance vs. type 2 diabetes
Common risk factors
Visceral fat and metabolic health
The role of muscle
Whether carbohydrates cause insulin resistance
How sleep and stress affect metabolic health
What tests healthcare professionals use
Whether insulin resistance can improve
Practical steps you can take after 50
QUICK ANSWER: WHAT IS INSULIN RESISTANCE?
Insulin resistance occurs when cells in important metabolic tissues—particularly muscle, liver, and fat tissue—become less responsive to insulin.
Insulin helps regulate blood glucose and coordinates how the body stores and uses energy.
When tissues become less responsive, the pancreas may compensate by producing more insulin to maintain blood glucose.
For some people, this compensation can work for years.
Eventually, if the pancreas can no longer produce enough insulin to overcome the resistance, blood glucose may rise.
This can contribute to:
Pre-diabetes.
And eventually, in some people:
Type 2 diabetes.
Insulin resistance is influenced by a combination of genetics, body composition, physical activity, diet, sleep, medications, age, and other metabolic and medical factors.
It is not simply caused by eating one particular food.
FIRST, WHAT IS INSULIN?
Insulin is a hormone produced by specialized beta cells in your pancreas.
Your pancreas sits behind your stomach.
When you eat carbohydrates, digestion breaks many of them down into glucose.
That glucose enters your bloodstream.
Your blood glucose rises.
Your pancreas responds by releasing insulin.
Insulin then helps your body manage that glucose.
One of its important jobs is helping muscle and fat cells take up glucose from the bloodstream.
Insulin also tells the liver to reduce glucose production and helps regulate the storage and use of nutrients.
Think of insulin as part of your body's:
ENERGY MANAGEMENT SYSTEM.
Insulin isn't bad.
You need it.
Without sufficient insulin action, blood glucose can rise to dangerous levels.
WHAT DOES "INSULIN RESISTANT" MEAN?
Let's use a simple analogy.
Imagine insulin is sending a message:
"We have glucose available. Let's move and store this energy appropriately."
In an insulin-sensitive system, tissues respond effectively.
But with insulin resistance, the response becomes weaker.
The pancreas recognizes that glucose still needs to be controlled.
So it compensates.
It produces:
MORE INSULIN.
Now there's a stronger signal.
For a while, that may work.
Your glucose can still look relatively normal.
But your body is having to work harder to maintain that normal result.
That's an important concept.
YOUR BLOOD SUGAR CAN BE NORMAL WHILE INSULIN RESISTANCE IS DEVELOPING
This surprises a lot of people.
They think:
"My glucose is normal, so everything must be perfect."
Not necessarily.
During early insulin resistance, your pancreas may be able to produce enough additional insulin to compensate.
Blood glucose remains within the normal range.
But insulin levels may be higher than they previously were.
Over time, if insulin resistance worsens and the pancreatic beta cells cannot keep compensating adequately, glucose begins rising.
This is one pathway toward:
Pre-diabetes.
And eventually:
Type 2 diabetes.
That progression isn't inevitable.
But understanding it gives us an opportunity to take metabolic health seriously before complications develop.
INSULIN RESISTANCE IS NOT THE SAME AS DIABETES
This distinction matters.
INSULIN RESISTANCE
Your tissues aren't responding to insulin as effectively as they should.
PREDIABETES
Blood glucose levels are above the normal range but don't yet meet diagnostic criteria for diabetes.
TYPE 2 DIABETES
Blood glucose has reached established diagnostic thresholds because insulin action and insulin production are no longer sufficient to maintain normal glucose regulation.
These conditions are related.
But they aren't identical.
Someone can have insulin resistance without meeting criteria for pre-diabetes.
And someone with pre-diabetes doesn't automatically progress to type 2 diabetes.
Risk can often be changed.
WHY DOES INSULIN RESISTANCE DEVELOP?
There isn't one cause.
That's important because social media likes simple explanations.
You'll hear:
"Carbs cause insulin resistance."
Or:
"Sugar causes insulin resistance."
Or:
"Being overweight causes insulin resistance."
The biology is more complicated.
Risk factors can include:
Genetics.
Family history.
Excess body fat.
Visceral fat.
Physical inactivity.
Aging.
Certain dietary patterns.
Sleep problems.
Certain medications.
Hormonal disorders.
Polycystic ovary syndrome.
And other medical factors.
Some people develop significant insulin resistance without having obesity.
Others may have obesity without the same degree of metabolic dysfunction.
We are individuals.
VISCERAL FAT MATTERS
Yesterday we talked about visceral fat in relation to chronic inflammation.
It matters here too.
Visceral fat is the fat stored around your internal abdominal organs.
It's different from the subcutaneous fat directly underneath your skin.
Visceral adipose tissue is metabolically active.
Excess visceral fat is strongly associated with:
Insulin resistance.
Elevated triglycerides.
Fatty liver disease.
High blood pressure.
Type 2 diabetes.
And cardiovascular risk.
This is why waist size can sometimes provide useful metabolic information beyond body weight alone.
The goal isn't just:
"Get lighter."
It's:
IMPROVE BODY COMPOSITION AND METABOLIC HEALTH.
MUSCLE IS A MAJOR PLAYER IN BLOOD-SUGAR CONTROL
This is one of my favorite parts of this discussion because it gives us something practical to work on.
Skeletal muscle is a major site of glucose disposal, particularly after meals.
When insulin signals muscle cells, those cells can take glucose out of the bloodstream and use or store it.
Now think about what happens as we age.
Without appropriate resistance exercise, physical activity, and nutrition, we can gradually lose muscle.
That's called:
SARCOPENIA.
Less muscle isn't just a strength issue.
Muscle is metabolically important tissue.
That's one reason I continue emphasizing strength training throughout this Healthy Aging After 50 series.
We're not lifting weights simply to look better.
We're protecting:
Strength.
Mobility.
Bone health.
Independence.
And metabolic health.
Muscle matters.
EXERCISE CAN HELP EVEN BEFORE YOU LOSE WEIGHT
This is important.
People sometimes think exercise only "worked" if the scale went down.
That's not true.
Physical activity can improve insulin sensitivity even before dramatic weight loss occurs.
During muscle contraction, skeletal muscle can increase glucose uptake through mechanisms that aren't completely dependent on insulin.
Regular exercise can also improve insulin responsiveness over time.
That's why both:
AEROBIC EXERCISE
and
RESISTANCE TRAINING
can be valuable for metabolic health.
You don't need to choose one.
Walk.
Lift.
Move.
Do it consistently.
DOES EATING CARBOHYDRATES CAUSE INSULIN RESISTANCE?
Not automatically.
Carbohydrates naturally stimulate insulin because many carbohydrates are digested into glucose.
That's normal physiology.
An increase in insulin after eating doesn't mean you've developed insulin resistance.
Healthy people produce insulin after meals too.
The bigger issue is your overall metabolic environment.
A dietary pattern consistently providing excessive calories—particularly when combined with physical inactivity, increasing visceral fat, poor sleep, and genetic susceptibility—can contribute to metabolic dysfunction.
But carbohydrates include:
Beans.
Fruit.
Vegetables.
Oats.
Whole grains.
Lentils.
And many other nutritious foods.
Putting blueberries and sugar-sweetened soda into the same category simply because both contain carbohydrates doesn't make much nutritional sense.
Food quality matters.
Quantity matters.
Your overall diet matters.
WHAT ABOUT SUGAR?
Again, context matters.
Eating sugar doesn't instantly make someone insulin resistant.
But regularly consuming large amounts of added sugars—especially sugar-sweetened beverages—can make it easier to consume excess calories and is associated with poorer metabolic health.
Liquid calories are particularly easy to over-consume.
Think about:
Soda.
Sweet tea.
Sugary coffee drinks.
Energy drinks.
Fruit-flavored drinks.
One practical strategy is simple:
DRINK MORE WATER AND FEWER SUGARY BEVERAGES.
We talked about that in Day 21.
Simple habits overlap.
That's how health works.
WHAT ABOUT PROTEIN?
Adequate protein becomes increasingly important as we age because it supports muscle maintenance and growth when combined with resistance training.
Protein can also contribute to satiety.
But protein isn't a magical treatment for insulin resistance.
The bigger picture still matters:
Total diet.
Calories.
Body composition.
Exercise.
Sleep.
Genetics.
And medical conditions.
I like protein because it helps us protect muscle.
And protecting muscle after 50 should be a priority.
WHAT ABOUT INTERMITTENT FASTING?
Intermittent fasting and time-restricted eating have received enormous attention.
Some studies suggest these approaches can improve certain metabolic markers in some people, particularly when they help reduce overall energy intake or body weight.
But fasting isn't required to improve insulin sensitivity.
And it isn't appropriate for everyone.
People taking glucose-lowering medications can be at risk for low blood sugar depending on their treatment.
People with certain medical conditions, nutritional needs, or histories of disordered eating may also require different approaches.
The best dietary strategy is one that is:
Nutritionally adequate.
Medically appropriate.
Sustainable.
And something you can actually follow.
DOES INSULIN RESISTANCE MAKE IT IMPOSSIBLE TO LOSE WEIGHT?
No.
This is another claim I see too often.
Insulin resistance can influence metabolism and may make weight management more challenging for some individuals.
But it doesn't make fat loss biologically impossible.
Weight change remains influenced by long-term energy balance.
The practical challenge is that metabolic health can influence:
Hunger.
Energy expenditure.
Food choices.
Activity.
And how easy or difficult a particular plan feels.
So instead of saying:
"My insulin won't let me lose weight..."
I prefer:
"What habits and medical factors can I improve?"
That's a much more productive question.
CAN INSULIN RESISTANCE CAUSE BELLY FAT?
The relationship goes both ways.
Excess visceral fat can contribute to insulin resistance.
Insulin resistance and metabolic dysfunction can also influence how the body handles and stores energy.
But belly fat doesn't automatically prove someone is insulin resistant.
And someone with a flat stomach isn't automatically metabolically healthy.
Again:
Don't diagnose yourself by looking in the mirror.
DOES CHRONIC INFLAMMATION PLAY A ROLE?
Yes, but this is another area where we need nuance.
Insulin resistance and chronic low-grade inflammation are closely connected.
Excess adipose tissue can release inflammatory signaling molecules.
Those signals may interfere with normal insulin signaling.
At the same time, metabolic dysfunction can contribute to additional inflammatory activity.
It's a complicated relationship.
This is why yesterday's article on chronic inflammation flows directly into today's discussion.
These systems don't operate independently.
Your body is interconnected.
SLEEP MATTERS MORE THAN PEOPLE REALIZE
Poor sleep doesn't simply make you tired.
Sleep restriction and sleep disruption can affect:
Glucose regulation.
Appetite.
Hormones.
Sympathetic nervous-system activity.
And insulin sensitivity.
Sleep apnea deserves particular attention.
Obstructive sleep apnea is associated with metabolic and cardiovascular problems.
If you:
Snore loudly.
Stop breathing during sleep.
Wake gasping.
Wake with headaches.
Or remain excessively sleepy during the day...
talk with a healthcare professional.
Treating sleep as optional isn't a good long-term health strategy.
We'll explore sleep much more deeply on Day 27.
WHAT ABOUT STRESS?
Stress is another piece of the metabolic puzzle.
During stress, your body releases hormones including:
Cortisol.
Epinephrine.
Those hormones help make energy available when you need it.
That's useful during a genuine threat.
But chronic stress can influence:
Sleep.
Eating behavior.
Physical activity.
Blood pressure.
And glucose regulation.
Stress isn't the sole cause of insulin resistance.
But chronic stress can make healthy metabolic habits more difficult.
HOW DO YOU KNOW IF YOU'RE INSULIN RESISTANT?
Here's where things become tricky.
There isn't one universally used routine test that simply says:
"Insulin resistance: YES or NO."
Healthcare professionals often assess metabolic health using a combination of:
Medical history.
Physical examination.
Blood glucose.
Hemoglobin A1C.
Lipid levels.
Blood pressure.
Waist circumference.
And other information.
In research settings, there are more sophisticated methods for measuring insulin sensitivity.
Clinicians may sometimes measure fasting insulin or use calculations based on glucose and insulin.
But these aren't universally standardized as routine diagnostic tools for everyone.
That's why I don't recommend diagnosing yourself from a fasting insulin number you found online.
WHAT IS A1C?
Hemoglobin A1C provides an estimate of your average blood glucose over roughly the previous two to three months.
It's commonly used to help:
Screen for pre-diabetes.
Diagnose diabetes.
Monitor diabetes.
Under commonly used U.S. diagnostic criteria:
NORMAL
Below 5.7%
PREDIABETES
5.7% to 6.4%
DIABETES
6.5% or higher
A diagnosis generally requires appropriate clinical confirmation unless there are clear symptoms and other qualifying findings.
Certain medical conditions can also make A1C less reliable.
So again:
Use the test with appropriate medical interpretation.
WHAT ABOUT FASTING GLUCOSE?
Fasting plasma glucose is another common test.
Under commonly used U.S. criteria:
NORMAL
99 mg/dL or below
PREDIABETES
100–125 mg/dL
DIABETES
126 mg/dL or higher
Again, a single home glucose-meter reading isn't the same thing as a formal medical diagnosis.
Laboratory testing and clinical interpretation matter.
WHAT ARE SOME CLUES OF METABOLIC DYSFUNCTION?
Insulin resistance itself often produces no obvious symptoms.
But certain findings may suggest increased metabolic risk.
These can include:
Increasing waist circumference.
Elevated triglycerides.
Low HDL cholesterol.
High blood pressure.
Elevated fasting glucose.
Elevated A1C.
Fatty liver disease.
Pre-diabetes.
Polycystic ovary syndrome.
Or a strong family history of type 2 diabetes.
One sign sometimes associated with significant insulin resistance is:
ACANTHOSIS NIGRICANS.
This is an area of darker, thicker, velvety skin that commonly appears around the neck, armpits, or other skin folds.
If you notice unexplained skin changes, have them evaluated rather than diagnosing yourself.
CAN INSULIN RESISTANCE IMPROVE?
Yes.
This is the encouraging part.
Insulin sensitivity is not necessarily fixed.
Depending on the cause and individual circumstances, metabolic health can often improve significantly through:
Physical activity.
Weight reduction when appropriate.
Improved body composition.
Dietary changes.
Better sleep.
Treatment of sleep apnea.
And appropriate medical therapy when needed.
Research from the Diabetes Prevention Program showed something especially important.
Among adults at high risk for type 2 diabetes, an intensive lifestyle intervention emphasizing weight loss and physical activity substantially reduced progression to diabetes.
That's powerful.
Lifestyle isn't magic.
But lifestyle matters.
WHAT SHOULD YOU DO AFTER 50?
Here's where we turn information into action.
1. WALK MORE
Walking is one of the simplest tools available.
A short walk after meals may also help reduce post-meal glucose excursions.
2. STRENGTH TRAIN
Build and maintain muscle.
Your muscles are metabolically important.
3. REDUCE EXCESS VISCERAL FAT WHEN APPROPRIATE
You don't need to become skinny.
Improve body composition.
4. EAT MORE FIBER-RICH FOODS
Vegetables.
Beans.
Lentils.
Fruit.
Whole grains.
Nuts.
Seeds.
5. PRIORITIZE PROTEIN
Especially as part of a plan to maintain or build muscle.
6. REDUCE SUGAR-SWEETENED BEVERAGES
Drink water more often.
7. PROTECT YOUR SLEEP
Aim for adequate, consistent sleep.
8. MANAGE STRESS
Don't ignore the effect your daily lifestyle has on your metabolic health.
9. KNOW YOUR NUMBERS
Talk with your healthcare provider about:
Blood glucose.
A1C.
Blood pressure.
Cholesterol.
Triglycerides.
And your overall metabolic risk.
10. DON'T WAIT FOR DIABETES
Pre-diabetes and metabolic risk deserve attention.
The earlier you improve your habits, the better.
DO YOU NEED A SUPPLEMENT FOR INSULIN RESISTANCE?
This is where I want to keep expectations realistic.
You'll see supplements marketed for:
"Blood sugar support."
"Insulin sensitivity."
"Glucose control."
Some ingredients have been studied.
But no supplement should become an excuse to ignore:
Diet.
Exercise.
Body composition.
Sleep.
Medical care.
Or prescribed medication.
And supplements can interact with diabetes medications or contribute to low blood sugar in some circumstances.
If you're taking medication for diabetes or another medical condition, discuss supplements with your healthcare professional or pharmacist.
Supplements can be tools.
They aren't substitutes for the foundation.
MYTHS VS. FACTS
Myth: Insulin is bad.
Fact: Insulin is an essential hormone required for normal metabolism and blood-glucose regulation.
Myth: Eating carbohydrates means you're insulin resistant.
Fact: Insulin normally rises after carbohydrate-containing meals. Insulin resistance refers to reduced tissue responsiveness to insulin.
Myth: Insulin resistance and diabetes are the same thing.
Fact: They're related but distinct. Insulin resistance can exist before blood glucose reaches the diagnostic range for diabetes.
Myth: If my fasting glucose is normal, I definitely have perfect insulin sensitivity.
Fact: The pancreas can sometimes compensate for insulin resistance by producing more insulin, maintaining normal glucose for a period of time.
Myth: Insulin resistance makes weight loss impossible.
Fact: It may make weight management more challenging for some people, but it doesn't make fat loss impossible.
Myth: Only people with obesity become insulin resistant.
Fact: Excess body fat increases risk, but genetics, physical activity, age, medications, medical conditions, and other factors also matter.
Myth: You need a special supplement to reverse insulin resistance.
Fact: Exercise, appropriate weight management, nutritious eating, sleep, and medical treatment when needed have much stronger roles in metabolic health.
COACH MARCUS TAKEAWAYS
Here's what I want you to remember.
1. Insulin is not the enemy.
Your body needs it.
2. Insulin resistance means important tissues are responding less effectively to insulin.
3. Your pancreas may compensate by producing more insulin.
4. Blood glucose can remain relatively normal during early insulin resistance.
5. Insulin resistance can contribute to prediabetes and type 2 diabetes.
6. Visceral fat is strongly associated with metabolic dysfunction.
7. Muscle is one of your most important metabolic tissues.
8. Both aerobic exercise and strength training can support insulin sensitivity.
9. Sleep, stress, nutrition, body composition, genetics, and medical conditions all matter.
10. Metabolic health can often improve significantly.
MY FINAL THOUGHT
Here's what I hope you take away from today's article.
Don't wait until someone tells you:
"You have diabetes."
Before you start caring about metabolic health.
Your body may spend years adapting before blood sugar becomes obviously abnormal.
That's why prevention-oriented healthy living matters.
Know your numbers.
Watch your waistline.
Build muscle.
Walk.
Lift weights.
Eat more real food.
Drink more water.
Sleep.
Manage stress.
And pay attention to what your body is telling you.
I especially want people over 50 to understand the importance of muscle.
We sometimes become obsessed with losing weight.
I don't just want to weigh less.
I want to be:
Stronger.
More metabolically healthy.
More mobile.
More capable.
And more independent.
That means protecting muscle while improving body composition.
The scale is only one piece of information.
Your health is bigger than a number.
And if your blood sugar or A1C begins moving in the wrong direction, don't look at it as failure.
Look at it as information.
Information gives you an opportunity to act.
Work with your healthcare provider.
Improve the things you can improve.
Use medication when it's medically appropriate.
And give your body a better environment in which to function.
You don't have to become perfect tomorrow.
Start improving today.
Because getting older is automatic.
Getting better requires intention.
And remember:
DON'T JUST GET OLDER. GET BETTER AT IT.
Faith. Health. Wealth. Build All Three.
— Coach Marcus Jones
MEDICAL DISCLAIMER
This article is provided for general educational and informational purposes only. It is not intended to diagnose, treat, cure, or prevent insulin resistance, prediabetes, diabetes, metabolic syndrome, fatty liver disease, or any other medical condition. Insulin resistance and abnormal blood glucose can have multiple causes and should be evaluated within an individual's complete medical history. Laboratory results, including fasting glucose, hemoglobin A1C, fasting insulin, and other metabolic tests, should be interpreted by a qualified healthcare professional. Do not start, stop, or change diabetes medication, fasting practices, dietary supplements, or other treatments based on this article. People taking insulin or glucose-lowering medications should discuss significant dietary, fasting, supplement, or exercise changes with their healthcare professional because these changes can affect blood glucose and medication requirements.
SOURCE ANNOTATIONS & FURTHER READING
[Source 1] National Institute of Diabetes and Digestive and Kidney Diseases (NIDDK) — Insulin Resistance & Prediabetes
The NIDDK explains insulin resistance, its relationship with prediabetes and type 2 diabetes, associated risk factors, and the role of lifestyle changes and weight management in reducing metabolic risk.
[Source 2] Centers for Disease Control and Prevention — About Insulin Resistance and Diabetes
CDC resources explain how insulin helps glucose enter cells and how reduced insulin responsiveness can eventually contribute to elevated blood glucose and type 2 diabetes.
[Source 3] American Diabetes Association — Diagnosis of Diabetes and Prediabetes
The ADA publishes evidence-based standards addressing diabetes screening and diagnosis, including the use and interpretation of A1C, fasting plasma glucose, and oral glucose-tolerance testing.
[Source 4] Diabetes Prevention Program Research Group. Reduction in the Incidence of Type 2 Diabetes with Lifestyle Intervention or Metformin. New England Journal of Medicine. 2002.
In adults at high risk of developing type 2 diabetes, an intensive lifestyle program targeting approximately 7% weight loss and at least 150 minutes of physical activity per week reduced diabetes incidence by 58% compared with placebo over the original study period.
[Source 5] National Institute of Diabetes and Digestive and Kidney Diseases — Diabetes Prevention Program
Long-term follow-up of the Diabetes Prevention Program continues to demonstrate that lifestyle intervention can meaningfully delay or reduce progression to type 2 diabetes among people at elevated risk.
[Source 6] American College of Sports Medicine / American Diabetes Association — Exercise and Type 2 Diabetes
Research and professional guidance support both aerobic and resistance exercise for improving glucose regulation, insulin action, physical fitness, and overall metabolic health.
[Source 7] Scientific Literature on Skeletal Muscle and Glucose Metabolism
Skeletal muscle is a major site of insulin-stimulated glucose disposal. Physical activity and muscle contraction can increase glucose uptake, helping explain why maintaining active skeletal muscle is important for metabolic health.
RELATED ARTICLES IN THIS SERIES
Day 22: Why Is Heart Disease Still a Leading Cause of Death?
Day 23: Why Do Heart Attacks Occur More Often in the Morning?
Day 24: When Is the Best Time to Check Your Blood Pressure?
Day 25: What Is Chronic Inflammation?
Day 26: What Is Insulin Resistance? — Current Article
Day 27: Why Is Sleep So Important After 50?
Day 28: How Does Stress Affect Your Physical Health?
Day 29: What Happens When You Sit Too Much?
Day 30: What Are the Most Important Health Habits to Develop After 50?
NEXT: DAY 27
Why Is Sleep So Important After 50?
We'll look at what actually happens while you sleep, how sleep changes with age, the connection between sleep and your brain, heart, metabolism, hormones and immune system, why waking during the night becomes more common, and why sleep apnea deserves particular attention after 50.