The short answer: the private test for insulin resistance is a fasting insulin level with fasting glucose, from which HOMA-IR is calculated; the NHS does not usually offer it, because NICE identifies prediabetes with HbA1c or fasting glucose instead. If you only want those two markers, Medichecks' £79 Insulin Resistance Blood Test is the cheapest option we found; if you want them read alongside lipids, liver, thyroid and hormones, TrueVitals Ultimate includes fasting insulin, C-peptide and HOMA-IR. If you have symptoms of diabetes (thirst, passing urine often, weight loss), skip private testing and see your GP.
Insulin resistance means your muscles, liver and fat cells respond less to insulin, so the pancreas has to release more of it to keep blood glucose in range. It is not a diagnosis in itself; it is a state that can sit behind prediabetes, type 2 diabetes, fatty liver and PCOS.
Fasting insulin is the amount of insulin in your blood after an overnight fast. A high fasting insulin with a normal glucose suggests your body is working harder than usual to hold glucose steady.
HOMA-IR (Homeostatic Model Assessment of Insulin Resistance) combines fasting insulin and fasting glucose into one estimate. It was published by Matthews and colleagues in Oxford (Diabetologia, 1985):
Higher numbers suggest more insulin resistance. There is no NHS or NICE reference range for HOMA-IR, and cut-offs in published studies vary by population and insulin assay, so treat it as a trend and a piece of context, not a pass or fail.
C-peptide is released by the pancreas in equal amounts to insulin, so it reflects how much insulin your own body is producing. It is useful alongside fasting insulin, particularly if you are taking medicines that affect insulin.
None of these markers diagnoses diabetes. In the UK, prediabetes (non-diabetic hyperglycaemia) is identified by an HbA1c of 42 to 47 mmol/mol or a fasting glucose of 5.5 to 6.9 mmol/L (NICE PH38), and type 2 diabetes by an HbA1c of 48 mmol/mol or above (NICE NG28). See the HbA1c test and prediabetes blood test.
HbA1c and fasting glucose measure the result: how much sugar is in your blood. Fasting insulin measures the effort: how much insulin it takes to keep it there. While the pancreas can keep up, the result looks normal.
The clearest UK evidence comes from the Whitehall II cohort of British civil servants. Researchers tracked glucose, insulin sensitivity and insulin secretion for over a decade before people were diagnosed with type 2 diabetes, and found insulin sensitivity was already declining years before glucose rose sharply (Tabák et al., The Lancet, 2009).
That is the honest case for testing fasting insulin: it can show strain earlier than HbA1c. The honest limitation is that no UK guideline uses it to diagnose or treat anything, so a high result is a reason for lifestyle change and a conversation with your GP, not a label.
Weight gain around the waist; struggling to lose weight despite real effort; high triglycerides or low HDL on a cholesterol test; PCOS; a parent or sibling with type 2 diabetes; a past diagnosis of gestational diabetes; an HbA1c creeping up but still in range.
NICE recommends lower BMI thresholds for action in people of South Asian, Chinese, Black African and African-Caribbean family background, because type 2 diabetes risk rises at a lower BMI (NICE PH46). Being slim does not rule insulin resistance out.
Checked on each provider's own website on 15 October 2026. "Not listed" means the marker did not appear on the product page we checked; providers change panels, so confirm before you buy.
| Provider and test | Price | Fasting insulin | HOMA-IR | C-peptide | HbA1c | Results reviewed by |
|---|---|---|---|---|---|---|
| TrueVitals Ultimate (140 markers) | £349 + £19 clinic draw or £39 home visit | Yes | Yes | Yes | Yes | Clinician, written report of every result |
| Medichecks Insulin Resistance Blood Test | £79 | Yes | "Fasting insulin resistance index" | Not listed | Not listed | Doctor's comments (opt-out available) |
| Medichecks Optimal Health Blood Test | £249 (venous; clinic +£35, nurse +£59) | Not listed | Not listed | Not listed | Yes | Doctor's report |
| Lola Health Peak Insights 70 | £200 own phlebotomist; £235 clinic or home visit | Not listed | Not listed | Not listed | Yes | GMC-registered doctor |
| Thriva Metabolic Health Blood Test (19 markers) | £96 (nurse +£60) | Not named | Not named | Not named | Yes | GP-reviewed report |
| Forth Advanced Blood Test (47 markers) | £195 one-off (£167 subscription); venous | Not listed | Not listed | Not listed | Yes | Forth medical team; optional doctor comment |
| Randox Health Everyman Complete | £416 | Product page lists health areas ("Diabetes Health") but not individual markers; ask Randox before booking | Scientific advisor discussion; GP consult +£65 | |||
Prices checked October 2026. Sources: medichecks.com product pages (Insulin Resistance Blood Test, Optimal Health Blood Test); lolahealth.com/products/peak-insights; thriva.co Metabolic Health Blood Test; forthwithlife.co.uk Advanced Blood Test; randoxhealth.com Everyman Complete. Medichecks' page metadata describes its index as HOMA-IR. Thriva's page states 19 markers but does not name them all. Compare full panels: UK blood test companies compared.
You only want to know your fasting insulin. Medichecks' Insulin Resistance Blood Test at £79 is far cheaper than a 140-marker panel and includes doctor's comments. See Medichecks alternative for how the two compare more broadly.
You have symptoms of diabetes. Excessive thirst, passing urine more often, unexplained weight loss, blurred vision or slow-healing cuts need your GP and an HbA1c, not a private wellness test.
You want a broad panel and don't need insulin. Lola Health Peak Insights 70 (£200 self-arranged) or Thriva's Metabolic Health test (£96) include HbA1c and are cheaper than Ultimate. See Lola Health alternative and Thriva alternative.
You want a home kit. TrueVitals has no finger-prick kit: every sample is a venous draw at one of 103 partner clinics or a home visit, booked by phone after payment. Providers with home kits are more convenient, though not every marker can be measured from a finger-prick sample.
Where TrueVitals fits. If you suspect insulin resistance, the useful question is usually why, and that sits across lipids, liver enzymes, thyroid, sex hormones and inflammation as well as insulin. Ultimate measures 140 of those together and a clinician reviews a written report of every result. We are a newer brand than Medichecks, Thriva or Forth; judge us on the sample report.
There is no single diagnostic test. The usual private approach is a fasting insulin level measured alongside fasting glucose, from which HOMA-IR is calculated (fasting insulin × fasting glucose ÷ 22.5; Matthews et al., Diabetologia, 1985). C-peptide, triglycerides, HDL and HbA1c add context. NICE uses HbA1c or fasting glucose, not insulin, to identify prediabetes and diabetes (NICE PH38, NG28).
Yes. In the Whitehall II study of UK civil servants, insulin sensitivity was already falling years before glucose rose enough to diagnose type 2 diabetes (Tabák et al., The Lancet, 2009). While the pancreas can compensate by making more insulin, glucose and HbA1c can stay in range. A normal HbA1c is reassuring about current blood sugar; it does not measure how hard your body is working to keep it there.
Not usually for this purpose. NICE guidance identifies prediabetes and type 2 diabetes using HbA1c or fasting glucose (NICE PH38, NG28), so GPs rarely order fasting insulin or HOMA-IR for insulin resistance. If you have symptoms or risk factors, ask your GP for an HbA1c first: it is free and it is the test the NHS acts on.
There is no NHS or NICE reference range for HOMA-IR, and published studies use different cut-offs depending on the population and the insulin assay. That is why a single HOMA-IR figure should be read with the rest of the picture (triglycerides, HDL, HbA1c, waist, family history) rather than as a pass or fail. Your report should explain your result in that context.
Yes. Fasting insulin and HOMA-IR are only meaningful on a fasting sample, usually taken in the morning after an overnight fast with water only. Follow the instructions you are given; see fasting before a blood test.
On 15 October 2026: Medichecks sells a standalone Insulin Resistance Blood Test (£79) with fasting insulin and a fasting insulin resistance index. TrueVitals Ultimate (£349 + draw) includes fasting insulin, C-peptide and HOMA-IR within 140 biomarkers. Lola Health Peak Insights 70, Thriva Metabolic Health and Forth's Advanced Blood Test did not list fasting insulin or HOMA-IR on their product pages.
Insulin resistance is common in PCOS, and the 2023 International Evidence-based PCOS Guideline (Teede et al.) recommends checking glycaemic status at diagnosis and every one to three years, preferably with an oral glucose tolerance test, or with fasting glucose or HbA1c. Fasting insulin can add context but is not the guideline's screening test, so speak to your GP about the guideline tests first.
Ultimate measures fasting insulin, C-peptide and HOMA-IR alongside the rest of the panel, with a clinician-reviewed report within 4 working days. 140 biomarkers (139 for women), £349 plus £19 clinic draw or £39 home visit.
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