🩺 Diabetes
Insulin Resistance Signs — How to Know If You Have It (2026)
The warning signs of insulin resistance, how to test for it, and the most effective strategies to reverse it naturally. Updated January 2026.
Key Takeaways
- 1 in 3 UK adults and 40% of Americans have some degree of insulin resistance
- Acanthosis nigricans (dark skin patches) is the most visible sign
- Fasting insulin level above 15 mIU/L indicates likely insulin resistance
- A HOMA-IR score above 2.9 is the standard clinical definition
- Insulin resistance is reversible in most cases with lifestyle change
What Is Insulin Resistance?
Insulin resistance occurs when cells in your muscles, fat, and liver don't respond normally to insulin — requiring the pancreas to produce increasingly more insulin to achieve the same glucose-lowering effect. Over time, the pancreas cannot compensate, leading to prediabetes and eventually Type 2 diabetes.
1 in 3
UK adults have some degree of insulin resistance
HOMA-IR >2.9
Standard clinical definition of insulin resistance
Reversible
In most cases with lifestyle change
Signs and Symptoms
Physical Signs
- Acanthosis nigricans: Dark, velvety, thickened skin in the neck creases, armpits, and groin — the most visible physical sign of insulin resistance
- Central obesity: Abdominal fat accumulation — waist above 94cm (men) or 80cm (women)
- Skin tags: Small, soft skin growths around the neck and armpits — associated with insulin resistance
Metabolic Signs (Blood Tests)
- Fasting glucose 5.6–6.9 mmol/L (prediabetes range)
- HbA1c 42–47 mmol/mol (prediabetes range)
- High triglycerides (above 1.7 mmol/L fasting)
- Low HDL cholesterol (below 1.0 mmol/L men, 1.2 mmol/L women)
- High uric acid — often associated with insulin resistance
- Non-alcoholic fatty liver disease on ultrasound
Symptoms
- Fatigue, especially after carbohydrate-heavy meals
- Strong carbohydrate cravings and difficulty feeling satisfied
- Brain fog and difficulty concentrating
- Difficulty losing weight despite dietary effort
- Frequent urination and increased thirst (later stages)
How to Test for Insulin Resistance
| Test | Normal | Insulin Resistance | Availability |
|---|---|---|---|
| Fasting glucose | Below 5.6 mmol/L | 5.6–6.9 mmol/L | NHS (any GP) |
| HbA1c | Below 42 mmol/mol | 42–47 mmol/mol | NHS (any GP) |
| Fasting insulin | Below 15 mIU/L | Above 15 mIU/L | Private (£25–40) |
| HOMA-IR | Below 2.0 | Above 2.9 | Calculated from above |
✅ How to Reverse Insulin Resistance
1. Reduce refined carbohydrates and added sugar. 2. Resistance training 3×/week — muscle is the largest insulin-sensitive tissue. 3. Lose 5–10% body weight if overweight. 4. Improve sleep (poor sleep worsens insulin sensitivity acutely). 5. Reduce chronic stress (cortisol opposes insulin action). 6. Add dietary fibre 25–35g/day. Most people with early insulin resistance can achieve normal sensitivity within 3–6 months of consistent lifestyle change.🔢 Free Tool
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Open Free Calculator →Frequently Asked Questions
What is a normal insulin level?▼
Fasting serum insulin: normal is below 15 mIU/L (some labs below 10 mIU/L). HOMA-IR (calculated as fasting glucose mmol/L × fasting insulin mIU/L ÷ 22.5): normal below 2.0, borderline 2.0–2.9, insulin resistance above 2.9. Note: fasting insulin is not routinely measured on NHS — request it specifically or access via private testing.
Can you have insulin resistance with normal blood sugar?▼
Yes — in early insulin resistance, the pancreas compensates by secreting 2–5× more insulin than normal to maintain blood glucose in the normal range. Blood glucose appears normal but fasting insulin is elevated. This compensated state can persist for years before glucose eventually rises. Fasting insulin testing reveals insulin resistance before glucose becomes abnormal.
What foods cause insulin resistance?▼
Primary dietary drivers: refined carbohydrates (white bread, white rice, sugar), ultra-processed foods, sugary drinks (fastest insulin response of any food), and excess saturated fat (impairs insulin receptor signalling). NOT: whole grains, legumes, or natural fruit sugars in moderation. Consistent calorie excess causing visceral fat accumulation is the strongest overall dietary driver.
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⚕️ Medical Disclaimer: For informational purposes only. Always consult a qualified healthcare professional before starting or changing any medication or treatment.
PS
Consultant Endocrinologist
All articles reviewed by qualified healthcare professionals following NHS, AHA, and WHO guidelines.