Fasting insulin and HOMA-IR: spotting insulin resistance early

Fasting insulin can rise years before your blood sugar does, making it an early clue to insulin resistance. Yet insulin is rarely measured by default, while glucose is. If you want to steer your metabolic health early, you look at insulin and HOMA-IR, not just glucose.

I think this is the clearest example of measuring too late. By the time your glucose is abnormal, your body has often been compensating for years.

Why does insulin rise before glucose?

In early insulin resistance, your body makes more insulin to keep your blood sugar normal. Your glucose therefore stays within range for a long time, while your insulin is already climbing. Only when your pancreas can no longer keep up does your glucose rise too.

That is why a normal glucose looks reassuring, but a raised insulin tells the real story.

What is HOMA-IR?

HOMA-IR is a simple calculation that combines your fasting glucose and insulin into a measure of insulin sensitivity. The formula was developed as a practical estimate of insulin resistance and matches more complex methods well (Matthews, 1985). A higher HOMA-IR points to more resistance.

So you need two values for it: fasting glucose and fasting insulin.

What do your values say?

No single value is proof, but together they sketch your sugar handling. This table gives a rough reading guide.

For the longer term, HbA1c adds to this, as it reflects your average blood sugar over weeks (Selvin, 2010).

What do you do with a raised insulin?

In its early stage, insulin resistance often responds well to lifestyle. Movement, strength training, weight loss and fewer fast sugars improve your insulin sensitivity. Prediabetes is also not a one-way street: a sizeable share returns to normal with lifestyle (Tabak, 2012).

To track your insulin and HOMA-IR, compose a panel through our custom blood test. Also read HbA1c in non-diabetics and the overview measuring metabolic health.

My advice: do not let a normal glucose reassure you if you suspect risk. Ask for insulin too and discuss a raised HOMA-IR with your GP.

References

1. 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. PMID: 3899825.
2. Tabak AG, Herder C, Rathmann W, et al. Prediabetes: a high-risk state for diabetes development. The Lancet. 2012. PMID: 22683128.
3. Selvin E, Steffes MW, Zhu H, et al. Glycated hemoglobin, diabetes, and cardiovascular risk in nondiabetic adults. New England Journal of Medicine. 2010. PMID: 20200384.

Disclaimer

Every blood test result includes a professional assessment by a BIG-registered doctor. This article gives general information and is not a substitute for medical advice. A blood test is a tool to walk into the conversation with your GP better informed, not a diagnosis in itself. For treatment decisions, discuss your results with your GP.