What is insulin resistance?
Insulin is the key that lets glucose into the cells. In insulin resistance that key turns ever more stiffly, and the pancreas solves that for years by simply making more insulin. Precisely that is why this stage is so invisible: glucose stays within the range while the machinery behind it runs at full speed. Complaints hardly belong with it; the first signals are in the values, not in how you feel. The traces can be read, though. Fasting glucose creeps up over the years, and between 6.1 and 6.9 mmol/L it is called impaired: not yet diabetes, but the antechamber. HbA1c summarises three months and moves slowly along. And often the fats are there first: rising triglycerides with a falling HDL is the classic trace of a liver that sees too much insulin, and a growing waist is the trace you see without a blood test. The cause is almost always a sum of belly fat, little muscle use, a lot of fast sugars and too little sleep, with disposition as an amplifier; in women PCOS belongs with it, and long-term prednisone or an underactive thyroid also lower sensitivity. Because the mechanism runs on lifestyle, it also runs back on it: working muscles take up glucose without insulin, and a smaller belly lets the liver listen again.
Which blood values show insulin resistance?
Every value below has its own page with the reference ranges of four Dutch labs.
| Value | What it shows | Points here when |
|---|---|---|
| Fasting glucosedefining | Creeps up through the years. Between 6.1 and 6.9 mmol/L it is called impaired. | high |
| HbA1c | The average of roughly three months. Moves slowly, and misses no single peak day because of it. | high |
| Triglycerides | Rises when the liver sees too much insulin. Often the earliest trace. | high |
| HDL Cholesterol | Falls in the same pattern. With triglycerides, the fat side of the story. | low |
| Triglycerides / HDL Ratio | The ratio of those two, and with that the most compact summary of this mechanism. | high |
What are the symptoms of insulin resistance?
These complaints are described for insulin resistance in guidelines and research. None of them is exclusive to it: the same complaints fit many other explanations, and an abnormal value can exist without any of them.
Insulin resistance itself you usually do not feel for years: as long as the pancreas can make extra insulin, blood sugar stays normal. Complaints such as thirst, frequent urination and blurred vision only belong with a blood sugar that is too high. Anyone who wants to know early therefore looks at their waist, their fats and their family, not at how they feel.
- Dark, velvety patches in skin foldsin research
Acanthosis nigricans, recognised by the American Diabetes Association as an indicator of insulin resistance. A sign you can see, not a complaint you feel.
Often named, not confirmed
You will run into these links everywhere. We list them deliberately, with what the research does show.
- Energy dip after a carbohydrate-rich mealnot confirmed
Often named, but sleepiness after a large meal is normal physiology; as a signal of insulin resistance it has never been demonstrated.
A complaint points in more than one direction, and a measurement explains no complaint: blood testing shows where your values stand, the reading and the diagnosis belong with your GP. The complaint list follows the Dutch GP guideline on type 2 diabetes (NHG) and the American Diabetes Association.
What causes insulin resistance?
Lifestyle and weight
Belly fat is hormonally active and muscle is the largest consumer of glucose; both sides count.
- Excess weight, especially around the belly
- Little muscle activity and much sitting
- Chronic short sleep
Predisposition
The same life does not give everyone the same resistance.
- Type 2 diabetes in the family
- A South Asian, Turkish, Moroccan or Surinamese background, where the risk starts earlier
- Previous gestational diabetes
Hormonal and medication
Sometimes something else drives the resistance.
- PCOS
- Long-term corticosteroids such as prednisone
What is insulin resistance confused with?
Each with the one value that tells the two apart.
Type 2 diabetes
The line is agreed: a fasting glucose of 7.0 mmol/L or higher, on two separate days, and that diagnosis is made by a doctor. Everything before it is this page's terrain.
Distinguishing value: Fasting glucose
Underactive thyroid
Weight gain and low energy here too, but through a different hormone. TSH keeps the two apart.
Distinguishing value: TSH
Inherited high triglycerides
Strongly raised triglycerides with tidy glucose values fits an inherited fat-metabolism variant sooner than insulin resistance. The whole pattern counts, not one value.
Distinguishing value: Triglycerides
What you do about insulin resistance
This is the picture that responds most strongly to lifestyle. Start with the belly: a smaller waist is the most powerful lever, because belly fat is the fat that makes liver and muscles deaf to insulin, and a few kilos off already changes sensitivity measurably. Cut soft drinks, fruit juice, sweets and white bread, because fast sugars demand the largest insulin peaks, and eat protein, fibre and vegetables with every meal, so the sugar comes in more slowly. Use your muscles, because they are the largest consumer of glucose and take it up during and after exertion without insulin being involved: daily movement, a walk after the meal, and strength training twice a week, because more muscle mass takes up more glucose permanently. Sleep seven to eight hours, because one short night already makes you less sensitive the next day, and drink less alcohol, which makes the liver produce extra triglycerides. Medicines only come into view once glucose reaches the diabetes limit, and even then lifestyle stays the foundation; metformin does at its core the same as exercise, making the liver listen again. Measure again after three months, fasting: the triglycerides fall first, fasting glucose follows, and HbA1c only shows after a full quarter what you have changed.
From which fasting glucose does a lab call it high?
This is what the four largest Dutch labs publish themselves, side by side.
4.0 – 6.0mmol/L
Between 3.9 and 4.0 and between 6.0 and 6.1 it depends on the lab, because each sets its limits on its own method and population. Above 6.1 every lab calls it abnormal.
every lab calls 4.0 – 6.0 mmol/L normal. Between 3.9 and 4.0 and between 6.0 and 6.1 it depends on the lab.
Every age group per lab
| Lab | Group | Reference range |
|---|---|---|
| Unilabs(Saltro, Medlon, SHO, Atalmedial)2026 | All adults | 4.0-6.1 mmol/L |
| Star-shl2026 | All adults | 4.0 - 6.0 mmol/L |
| Certe2026 | All ages | 3.9 - 6.1 mmol/L |
| Clinical Diagnostics2026 | All adults | 4.0-6.0 mmol/L |
How to get insulin resistance measured
- Fasting
- Fasting, at least eight hours. Fasting glucose cannot be judged otherwise; HbA1c does not care either way.
- Material
- Venous blood, drawn at one of our collection points.
- Results
- Results within 24 hours of analysis, in the app.
- Referral
- No referral from a GP required.
- Which test
- The comprehensive test (€229, single test) measures the values on this page.
- Where to draw
- You can draw at 250+ locations near you, no referral needed. See the locations
Frequently asked questions
Is insulin resistance the same as prediabetes?
They overlap, but they are different kinds of words. Insulin resistance is the mechanism: cells that listen less well to insulin. Prediabetes is a measurement label for the borderline zone, such as an impaired fasting glucose between 6.1 and 6.9 mmol/L or a raised HbA1c. You can have the mechanism for years before a measurement earns the label, and precisely in those years it is easiest to turn back with lifestyle.
Why do you not measure insulin or the HOMA index?
Because fasting insulin compares poorly between laboratories and no decision hangs on it in the Netherlands. The early traces are in values that are standardised and that you have measured anyway: fasting glucose, HbA1c, triglycerides and HDL, from one draw. The TyG index, calculated from fasting glucose and triglycerides, estimates insulin sensitivity from precisely those two numbers.
From which fasting glucose is it diabetes?
From 7.0 mmol/L, measured on two different days, and a doctor makes that diagnosis. Between 6.1 and 6.9 fasting glucose is called impaired: not yet diabetes, but the zone in which the body already works harder to keep sugar normal and in which losing weight, exercise and less sugar pay off most. Below 6.1 is healthy, and that is where lifestyle can take you back to.
Why do American HbA1c numbers differ from my report?
Different unit, same substance. American sources write HbA1c in percentages: 5.7 is called the start of prediabetes there and 6.5 diabetes. In the Netherlands it is in mmol/mol, where those same limits lie around 40 and 48, and diabetes is moreover established on glucose and not on HbA1c. Anyone who sets their report beside an American table compares units and not bodies.
Can you reverse insulin resistance?
Yes, and better than most blood values. Muscle mass and exercise raise sensitivity, weight loss around the belly lowers resistance, and fewer fast sugars and enough sleep do the rest. The values move along in order: the triglycerides within weeks, fasting glucose within months, and HbA1c looks three months back, so what you change only shows fully at the next measurement.
Sources
- 1.NHG-Standaard Diabetes mellitus type 2. 2026. richtlijnen.nhg.org
- 2.American Diabetes Association, Standards of Care. 2026. diabetesjournals.org
- 3.WHO, Classification of diabetes mellitus. 2019. who.int
This page explains what a result means. It is not a diagnosis and not treatment advice. Discuss complaints or an abnormal value with your doctor.
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