Why standard results miss it
When cells respond less to insulin, the pancreas makes more of it, and glucose stays in range. That compensation can hold for a decade or more. In the Whitehall II cohort, glucose and insulin markers shifted years before people were diagnosed with type 2 diabetes (Tabák et al., 2009). A panel that stops at fasting glucose and HbA1c will read as normal for most of that time.
So the useful question is whether insulin is working harder to keep glucose there, and whether the markers are drifting in the same direction across tests.
Markers, reference ranges and Vively optimal ranges
| Marker | Typical lab reference | Vively optimal |
|---|---|---|
| Fasting insulin | 3 to 10 mIU/L | 3 to 5 mIU/L |
| HOMA-IR | 0.6 to 2.9 | 1.0 or below |
| Fasting glucose | 3.4 to 5.4 mmol/L | Read with insulin and HbA1c |
| HbA1c | 4.0 to 5.9% (20 to 41 mmol/mol) | 4.0 to 5.3% (20 to 34 mmol/mol) |
| Triglycerides | 0.5 to 2.1 mmol/L | 0.5 to 1.2 mmol/L |
| HDL cholesterol (men) | Above 1.0 mmol/L | 1.0 to 2.5 mmol/L |
| HDL cholesterol (women) | Above 1.0 mmol/L | 1.2 to 3.0 mmol/L |
| Triglyceride to HDL ratio (men) | Below 1.3 | Below 1.1 |
| Triglyceride to HDL ratio (women) | Below 1.0 | Below 0.7 |
These are adult ranges from the Vively Biomarker Master List. Labs set their own reference ranges, so read each result against the range on your client’s report. Most labs do not print the triglyceride to HDL ratio, so its cut-offs are Vively’s. They use the Australian molar ratio (both values in mmol/L), which is about 2.3 times smaller than the mg/dL ratio in many US papers. Vively optimal is a second reference for tracking change over time, not a diagnostic cut-off.
Two calculated markers add to the picture. HOMA-IR combines fasting insulin and fasting glucose into one score (Matthews et al., 1985). The triglyceride to HDL ratio rises with insulin resistance as triglycerides climb and HDL falls (McLaughlin et al., 2003). Some practitioners also use the TyG index, calculated from fasting triglycerides and glucose.
How to read them together
- High fasting insulin or HOMA-IR, normal glucose and HbA1c. The earliest pattern: the pancreas is compensating. A fasting insulin above 5 mIU/L, or a HOMA-IR above 1.0, sits outside Vively optimal even when the lab flags nothing. Repeat in 3 to 6 months after diet, activity and sleep changes to show the direction.
- HbA1c creeping up inside the range, for example 5.2, then 5.4, then 5.6%, alongside a rising insulin. Glucose control is starting to slip. Diabetes Australia treats 6.0 to 6.4% as high risk.
- High triglycerides and low HDL. The lipid pattern of insulin resistance. Triglycerides above the Vively optimal of 1.2 mmol/L with an HDL at the low end of the range make it more likely, even before insulin is tested.
- ALT and GGT rising inside the range. Points towards liver fat, which travels with insulin resistance. Read the liver side in how to interpret liver function tests (LFTs).
- Normal fasting insulin with a high triglyceride to HDL ratio and central weight gain. Do not rule insulin resistance out on one insulin result. Fasting insulin varies from day to day, so repeat it before you decide.
Before you read a result: traps
- Fasting. Fasting insulin, glucose and HOMA-IR need 8 to 12 hours without food. A coffee with milk or a late snack raises insulin and makes HOMA-IR meaningless.
- Assays. Insulin assays are not standardised between labs, so compare a client against their own earlier results from the same lab.
- Illness, stress and sleep. Acute illness, a hard training block, poor sleep the night before and high stress can all push glucose and insulin up.
- Medicines. Corticosteroids raise glucose. Metformin, GLP-1 receptor agonists and SGLT2 inhibitors change glucose, insulin or HbA1c, and HOMA-IR is not valid for anyone taking insulin.
- HbA1c accuracy. Iron deficiency can falsely raise HbA1c; recent blood loss, haemolysis, haemoglobin variants and kidney disease can shift it either way. Read HbA1c with the full blood count and iron studies.
- Pregnancy. Insulin sensitivity changes through pregnancy, and gestational diabetes has its own testing pathway with the GP or obstetric team.
Worked example
Sarah is a 44-year-old example client. Over three tests her fasting insulin went 6.8, 8.1 and 9.6 mIU/L and her HOMA-IR went from 1.51 to 2.22. Her HbA1c went 5.2, 5.4 and 5.6%, and her fasting glucose stayed at 5.1 to 5.2 mmol/L. Her triglycerides rose to 1.6 mmol/L, her HDL fell slightly to 1.1 mmol/L, and her ALT went 18, 24 then 31 U/L.
Every value sat inside the lab range. Against Vively optimal, fasting insulin, HOMA-IR, HbA1c, triglycerides and ALT were all above target, and all were moving the same way. That is the pattern of early insulin resistance with possible liver fat, and it gives you a baseline to retest against after 3 to 6 months of changes.
When to refer back to the GP
Optimal ranges do not replace red flags. Work within your own scope of practice.
- HbA1c of 6.5% (48 mmol/mol) or more, or fasting glucose of 7.0 mmol/L or more: the diabetes range, which the GP needs to confirm and manage
- HbA1c of 6.0 to 6.4%, or fasting glucose of 6.1 to 6.9 mmol/L: high risk, worth a GP assessment of cardiovascular and diabetes risk
- Fasting glucose below 3.5 mmol/L, or symptoms of low blood sugar
- Thirst, passing more urine, blurred vision or unexplained weight loss with any raised glucose
- Triglycerides above 10 mmol/L, which raise the risk of pancreatitis
- Any raised glucose in pregnancy
For the full list across all markers, see blood test red flags: when to refer a client back to the GP.
Ordering these markers through Vively
Fasting insulin, HOMA-IR, fasting glucose, HbA1c, triglycerides, HDL and the liver enzymes are all part of the Vively Baseline Health Check. Results come back in the practitioner platform beside your client’s earlier results, so you can see the trend. You need to be a verified practitioner to refer tests. Request free practitioner access.
Dr Michelle Woolhouse works through a case like this in Vively Practitioner Masterclass Part 1.
What blood tests show insulin resistance?
Fasting insulin and HOMA-IR show it most directly. HbA1c and fasting glucose usually stay normal until later. Triglycerides, HDL, the triglyceride to HDL ratio, ALT and GGT add supporting evidence. Read them together and compare with earlier results, because the direction across tests tells you more than one value.
What is a good fasting insulin level?
The typical lab reference is 3 to 10 mIU/L, and the Vively optimal range is 3 to 5 mIU/L. The client must fast for 8 to 12 hours. Insulin assays differ between labs, so compare a client with their own earlier results from the same lab.
What HOMA-IR score suggests insulin resistance?
The typical lab reference runs from 0.6 to 2.9, though labs that print a score set their own range. Vively uses 1.0 or below as optimal. A score above 1.0 with normal glucose suggests the pancreas is working harder than it should. HOMA-IR is not valid for people taking insulin, and it depends on a true fasting sample.
Can someone have insulin resistance with a normal HbA1c?
Yes. HbA1c reflects average glucose, and glucose stays normal while insulin compensates, often for years. A normal HbA1c with a high fasting insulin, high triglycerides or a rising ALT can still point to insulin resistance.
How often should insulin markers be retested?
Every 3 to 6 months while you are making changes, using the same lab and the same fasting conditions. Insulin and triglycerides tend to move faster than HbA1c and HDL, so they show early progress.
Can naturopaths, nutritionists and dietitians order these tests through Vively?
Yes. You need to be a verified practitioner to refer tests. Fasting insulin, HOMA-IR, HbA1c, fasting glucose and lipids are part of the Vively Baseline Health Check, and results come back in the practitioner platform beside earlier results. Request free practitioner access to get started.
- Tabák AG, Jokela M, Akbaraly TN, et al. Trajectories of glycaemia, insulin sensitivity, and insulin secretion before diagnosis of type 2 diabetes: an analysis from the Whitehall II study. Lancet. 2009.
- Matthews DR, Hosker JP, Rudenski AS, et al. Homeostasis model assessment: insulin resistance and beta-cell function from fasting plasma glucose and insulin concentrations in man. Diabetologia. 1985.
- McLaughlin T, Abbasi F, Cheal K, et al. Use of metabolic markers to identify overweight individuals who are insulin resistant. Annals of Internal Medicine. 2003.
- Simental-Mendía LE, Rodríguez-Morán M, Guerrero-Romero F. The product of fasting glucose and triglycerides as surrogate for identifying insulin resistance in apparently healthy subjects. Metabolic Syndrome and Related Disorders. 2008.
- World Health Organization. Use of glycated haemoglobin (HbA1c) in the diagnosis of diabetes mellitus. 2011.
- Diabetes Australia and RACGP. Management of type 2 diabetes: a handbook for general practice.