Insulin Resistance: The Signs Your Blood Sugar Tests Might Be Missing

Quick Facts

 

• Insulin resistance means your cells are becoming less responsive to insulin.
• The pancreas may compensate by producing more insulin to maintain normal blood glucose.
• Your fasting glucose can be normal while insulin is elevated.
• HbA1c doesn’t measure insulin. It reflects average blood glucose exposure over the previous 2-3 months.
• HOMA-IR uses fasting glucose and fasting insulin together. It provides an estimate of insulin resistance but should not be treated as a standalone diagnosis.
• Insulin resistance doesn’t always cause obvious symptoms.
• Insulin resistance isn’t exclusive to people who are overweight. Body composition is only one part of metabolic health.
• PMOS and insulin resistance are closely linked. Insulin resistance is common in PMOS and may influence androgen production and ovulatory function.
• Insulin sensitivity can often be improved.

 

 

What is Insulin Resistance?

 

Insulin is a hormone produced by the pancreas.

One of its main jobs is to help move glucose from the bloodstream into cells, where it can be used for energy.

Think of insulin as the signal telling your cells that glucose is available.

When cells become less responsive to that signal, the pancreas may compensate by releasing increasing amounts of insulin.

Initially, that compensation can work remarkably well.

Your glucose may remain within the expected range because your pancreas is working harder in the background to keep it there.

This is why looking at glucose alone doesn’t necessarily tell you how much insulin your body required to achieve that glucose result.

Over time, if insulin resistance progresses and the pancreas can no longer compensate sufficiently, blood glucose may begin to rise.

 

 

Can you have insulin resistance with normal blood glucose?

 

Yes.

This is one of the most important concepts to understand when interpreting metabolic blood results.

Imagine two people both have a fasting glucose of 4.8 mmol/L.

On paper, their glucose looks identical.

But one person may require relatively little insulin to maintain that concentration, while another may need substantially more.

The glucose result shows us the outcome.

Insulin can provide additional information about what the body is doing to achieve it.

This doesn’t mean everyone with normal glucose needs extensive metabolic testing, nor does an isolated insulin result diagnose insulin resistance.

It means metabolic markers are often more informative when interpreted together rather than individually.

 

 

What are the symptoms of Insulin Resistance?

 

Insulin resistance doesn’t always cause obvious symptoms, particularly in its earlier stages.

Where symptoms or associated features are present, people may report:

• Fatigue or fluctuations in energy
• Feeling particularly tired after meals
• Increased hunger or difficulty feeling satisfied
• Sugar or carbohydrate cravings
• Difficulty managing body weight
• Increased abdominal fat
• Brain fog or difficulty concentrating
• Skin changes such as acanthosis nigricans
• Irregular menstrual cycles
• Features associated with PMOS

However, these symptoms are not specific to insulin resistance.

Fatigue, hunger, weight changes and menstrual disruption can occur for many reasons.

Symptoms should therefore prompt appropriate investigation rather than being used to self-diagnose insulin resistance.

 

Why HbA1c isn’t the same as an Insulin test

 

HbA1c is an extremely useful marker, but it answers a different question.

It provides an indication of your average blood glucose exposure over approximately the previous two to three months.

It does not directly measure insulin.

This means HbA1c may remain within the expected range during a period when the body is compensating for reduced insulin sensitivity by producing more insulin.

The same principle applies to fasting glucose.

Neither marker becomes “bad” or irrelevant – they simply measure different parts of metabolic health.

This is why clinical context matters.

 

 

What blood tests can help assess Insulin Resistance?

 

There isn’t one blood marker that should be interpreted in isolation as a definitive diagnosis of insulin resistance.

Depending on the individual and clinical indication, assessment may include:

 

Fasting Glucose

 

Fasting glucose measures the concentration of glucose circulating in your blood after a period without food.

It remains an important part of assessing glucose regulation.

 

HbA1c

 

HbA1c reflects longer-term exposure to glucose and is routinely used when assessing and monitoring diabetes and prediabetes.

 

Fasting Insulin

 

Fasting insulin measures circulating insulin following a period of fasting.

When interpreted alongside fasting glucose and the wider clinical picture, it can provide additional information about the amount of insulin being produced to maintain glucose levels.

Importantly, insulin assays and reference ranges can vary between laboratories, so a result shouldn’t be interpreted against an arbitrary “optimal” number found online.

 

HOMA-IR

 

HOMA-IR – the Homeostatic Model Assessment of Insulin Resistance – is a calculated value derived from fasting insulin and fasting glucose.

It can be useful as an estimate of insulin resistance, particularly in research and certain clinical settings.

However, HOMA-IR isn’t a standalone diagnostic test. Cut-offs can vary according to population, laboratory methodology and clinical context.

 

Lipid Profile

 

Insulin resistance can occur alongside changes in lipid metabolism.

Triglycerides, HDL cholesterol, LDL cholesterol and the wider lipid profile can therefore add useful context when assessing cardiometabolic health.

 

Liver Markers

 

Metabolic dysfunction and insulin resistance can also be associated with excess fat accumulation within the liver.

Markers such as ALT and GGT may therefore form part of a wider metabolic assessment, although normal liver enzymes do not exclude fatty liver disease.

 

 

Insulin Resistance and PCOS (Now PMOS)

 

The relationship between insulin resistance and polycystic ovary syndrome deserves particular attention.

Insulin resistance is common in PMOS, including in some women who don’t fit the stereotypical picture of being overweight.

Higher circulating insulin concentrations can interact with ovarian hormone production and may contribute to increased androgen activity.

This can be associated with features such as:

• Irregular or absent periods
• Acne
• Increased facial or body hair
• Scalp hair thinning
• Difficulty with ovulation

But PMOS is now finally acknowledged as a complex endocrine condition.

Insulin resistance isn’t present in every person with PMOS, and insulin testing alone cannot diagnose it.

If menstrual cycles are irregular or androgen-related symptoms are present, assessment may need to extend beyond glucose and insulin to include reproductive hormones, thyroid function, prolactin and other clinically appropriate investigations.

 

 

What causes Insulin Resistance?

 

There is rarely one single cause.

Genetics, body composition, diet, physical activity, sleep and hormonal health can all influence insulin sensitivity.

Risk can also be affected by factors including:

• Family history of type 2 diabetes
• Visceral or abdominal adiposity
• Physical inactivity
• PMOS
• Poor or insufficient sleep
• Certain medications
• Pregnancy and previous gestational diabetes
• Age
• Some endocrine conditions

This is also why insulin resistance shouldn’t simply be reduced to someone’s weight or diet.

Metabolic health is more complex than that.

 

 

Can insulin resistance be improved?

 

For many people, insulin sensitivity can improve significantly.

The appropriate intervention depends on what is driving the problem, but lifestyle changes remain an important first-line approach.

Regular physical activity is particularly valuable because skeletal muscle is one of the body’s major destinations for glucose.

Both resistance training and aerobic activity can improve insulin sensitivity.

Nutrition also matters, but improving insulin sensitivity doesn’t necessarily mean eliminating carbohydrates.

Instead, the focus may include improving overall dietary quality, increasing fibre, consuming adequate protein, reducing excessive intake of highly refined foods and considering how meals are structured.

Sleep is another frequently overlooked part of the picture. Persistent sleep restriction can negatively affect glucose regulation and insulin sensitivity.

For some people, addressing underlying conditions such as PMOS or reviewing medications may also form part of management.

 

When should you investigate further?

 

If you’re experiencing symptoms such as persistent fatigue, significant energy fluctuations, unexplained weight changes or irregular menstrual cycles – particularly alongside a family history of diabetes or other metabolic risk factors – it may be appropriate to discuss metabolic testing with a healthcare professional.

And if you’ve already been told your glucose is “normal”, that result is reassuring — but it may not necessarily answer every metabolic question.

The goal isn’t to order every available biomarker.

It’s to choose the right markers for the question you’re trying to answer.

Looking beyond a single result

 

At My Atlas, we believe blood results are most valuable when they’re interpreted in context.

A fasting glucose result tells us something.

HbA1c tells us something else.

Insulin, lipids, liver markers, hormones, symptoms, family history and lifestyle can add further pieces to the picture when clinically appropriate.

No individual marker should be used to create a diagnosis where one doesn’t exist.

But equally, being within a laboratory reference range doesn’t always mean there is nothing more worth understanding.

The aim of testing isn’t simply to collect more data. It’s to ask better questions of the data you already have.

Test. Understand. Take Action.

If you’re experiencing symptoms or want a more detailed understanding of your metabolic health, My Atlas provides advanced blood testing alongside clinical interpretation and GP support.

Rather than looking at individual biomarkers in isolation, we help you understand how your results fit together – and what, if anything, is worth acting on.

 

Explore My Atlas blood testing →

 

 

Frequently Asked Questions

 

Can I have insulin resistance with normal blood sugar?

 

Yes. During earlier stages of insulin resistance, the pancreas can compensate for reduced insulin sensitivity by producing more insulin. This may keep fasting glucose and HbA1c within expected ranges despite changes occurring in insulin regulation.

This is one reason glucose, HbA1c and insulin should not be considered interchangeable markers.

 

 

What are the first signs of insulin resistance?

 

Insulin resistance can develop without noticeable symptoms. When symptoms or associated features are present, they may include fatigue, energy crashes after eating, increased hunger, carbohydrate cravings, difficulty managing weight, increased abdominal fat or menstrual irregularities.

These symptoms are not specific to insulin resistance, so blood testing and appropriate clinical assessment are important rather than diagnosing the condition from symptoms alone.

 

 

What blood test shows insulin resistance?

 

There isn’t a single routine blood test that definitively diagnoses insulin resistance.

Fasting glucose, HbA1c and fasting insulin can provide different information about glucose and insulin regulation. Fasting glucose and insulin can also be used to calculate HOMA-IR, which provides an estimate of insulin resistance.

Results should be interpreted alongside other metabolic markers, symptoms, medical history and individual risk factors.

 

 

Does a normal HbA1c rule out insulin resistance?

 

No. HbA1c measures average glucose exposure rather than the amount of insulin required to regulate that glucose.

Someone may therefore have an HbA1c within the expected range while producing higher amounts of insulin to maintain glucose control.

A normal HbA1c is reassuring from a glucose perspective, but it does not directly assess insulin sensitivity.

 

 

What is fasting insulin?

 

Fasting insulin measures the amount of insulin circulating in the blood following a period without food.

When interpreted alongside fasting glucose, it can provide additional information about how much insulin the pancreas is producing to maintain glucose levels.

Fasting insulin shouldn’t be interpreted against a universal ‘optimal’ value, as assays, reference ranges and individual clinical circumstances vary.

 

 

What is HOMA-IR?

 

HOMA-IR stands for Homeostatic Model Assessment of Insulin Resistance.

It is calculated using fasting glucose and fasting insulin and is used to estimate insulin resistance.

A higher HOMA-IR may indicate reduced insulin sensitivity, but there is no single cut-off appropriate for every person or population. It should therefore form part of a wider metabolic assessment rather than being treated as a diagnosis by itself.

 

 

Is insulin resistance the same as prediabetes?

 

No.

Insulin resistance describes reduced responsiveness to insulin. Prediabetes refers to blood glucose levels that are higher than normal but below the diagnostic threshold for diabetes.

Insulin resistance can exist before glucose reaches the prediabetes range because the pancreas may initially compensate by producing additional insulin.

 

 

Can you have insulin resistance if you’re slim?

 

Yes.

Although increased visceral fat can contribute to insulin resistance, body weight alone doesn’t determine insulin sensitivity.

Genetics, PMOS, physical activity, sleep, medications, body composition and other metabolic or endocrine factors can all influence insulin sensitivity.

 

 

What is the connection between PMOS and insulin resistance?

 

Insulin resistance is common in PMOS, although it is not present in everyone with the condition.

Higher circulating insulin can influence ovarian androgen production and may contribute to features including irregular periods, difficulties with ovulation, acne, increased facial or body hair and scalp hair thinning.

This is why metabolic assessment can sometimes be relevant alongside reproductive hormone testing in people being investigated for PCOS.

 

 

Can insulin resistance be reversed?

 

Insulin sensitivity can often be significantly improved, particularly when contributing factors are identified early.

Regular physical activity, resistance training, adequate sleep, dietary changes and management of underlying conditions can all improve insulin sensitivity. Where medication is appropriate, this should be discussed with a healthcare professional.

The most effective approach depends on why insulin resistance has developed in the first place, rather than applying the same intervention to everyone.