Health Reference LibraryWhat are the symptoms of insulin resistance, and how do you check?
This entry is part of the Nutri Tailor Health Reference Library — cited research on supplements, nutrients and adjacent areas of health.
Summary
Insulin resistance is silent for years, and the recognisable pattern includes weight settling at the waist, energy and hunger crashes an hour or two after carbohydrate-heavy meals, afternoon fatigue, skin tags or darkened velvety skin at the neck and armpits, and irregular cycles or PCOS in women. The check is HbA1c rather than a single fasting glucose. Under 42 mmol/mol is the reference range, 42 to 47 is the at-risk zone where lifestyle pays most, and 48 and above is the diabetes threshold and a GP conversation. A waist over 94 cm in men or 80 cm in women, raised triglycerides with low HDL, and raised blood pressure support the reading. Weight loss, movement and fibre are what lower it.
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How it works
Insulin's job is to move glucose out of the blood into muscle, liver and fat. Resistance means those tissues respond less, so the pancreas produces more insulin to get the same effect, and for years glucose stays normal while insulin runs high. High insulin drives fat storage around the organs and the waist, blunts the fullness signal, and in women disrupts ovulation through its effect on the ovaries, the mechanism underneath PCOS. Eventually the pancreas cannot keep up and HbA1c drifts into the 42 to 47 zone, then past 48. The signs listed on this page are the footprints of high insulin, not high glucose, which is why they appear before any glucose test turns abnormal.
Timing
HbA1c re-tests at three months. Post-meal crashes improve within days of changing meal composition. Waist and insulin sensitivity move over weeks to months with weight loss and training. PCOS cycle regularity on inositol is judged at three to six months.
Safety profile
Thirst, frequent urination, unexplained weight loss, blurred vision or wounds that will not close mean glucose is already high and need a GP promptly. Darkened velvety skin that appears quickly in an adult who is not overweight needs a GP for other reasons. Chest pain, breathlessness or leg pain on walking with this pattern are cardiovascular questions. HbA1c at 48 or above is a GP diagnosis.
Special populations
South Asian, Black African and Caribbean adults develop insulin resistance at lower body weights and younger ages. Women with PCOS commonly have it regardless of weight. Pregnancy brings its own insulin resistance and gestational diabetes screening. Children and teenagers with darkened neck skin should be seen by a GP. Older adults lose muscle, which worsens glucose handling, and gain most from resistance training.
Guideline positions
The UK diagnostic framework is HbA1c: under 42 mmol/mol reference, 42 to 47 non-diabetic hyperglycaemia, 48 and above diabetes, per NICE NG28 and the WHO 2011 position, set out on the [HbA1c bands page](/apps/learn/what-do-hba1c-levels-mean-the-uk-bands-explained). There is no routine NHS test for insulin resistance itself; fasting insulin and the HOMA index are research tools. The 2023 international PCOS guideline recognises insulin resistance as central to PCOS and includes inositol as an option. The DiRECT trial showed the process reverses with weight loss, with remission of type 2 diabetes in 46 percent at a year.
Practical framework
Where the pattern fits, the GP request covers HbA1c, a lipid panel and blood pressure, and an NHS Health Check covers all three for adults aged 40 to 74. The waist is measured. HbA1c is read against the bands, and 42 to 47 is the number to act on hardest because it is still reversible. The levers then run on [how to lower blood sugar](/apps/learn/how-to-lower-blood-sugar-what-the-evidence-supports), meaning weight where there is weight to lose, daily movement with resistance training, fibre and carbohydrate quality, and sleep. Women with cycle irregularity alongside the pattern should raise PCOS with the GP and read the [inositol page](/apps/learn/inositol-what-it-does-who-it-helps-and-how-to-take-it). Nutri365 reads whether energy crashes, waist, sleep and HbA1c are moving together over months, checks for interactions and contraindications, and refers questions outside scope to a health specialist.
Common misconceptions
Being slim does not rule it out. A normal fasting glucose does not rule it out, because insulin can be high for years before glucose moves. Cutting carbohydrate to zero is not the answer, because weight, muscle and fibre are. Insulin resistance is not a condition to test for online and manage alone, and HbA1c through a GP is the real check.
Sources
- 2022. Type 2 diabetes in adults: management (NG28). NICE.
- 2011. Use of Glycated Haemoglobin (HbA1c) in the Diagnosis of Diabetes Mellitus. World Health Organization.
- Teede HJ, Tay CT, Laven JJE, et al; International PCOS Network 2023. Recommendations from the 2023 international evidence-based guideline for the assessment and management of polycystic ovary syndrome. European Journal of Endocrinology. PMID: 37580861
- Lean MEJ, Leslie WS, Barnes AC, et al 2018. Primary care-led weight management for remission of type 2 diabetes (DiRECT): an open-label, cluster-randomised trial. Lancet. DOI: 10.1016/S0140-6736(17)33102-1