Most annual checks include fasting glucose and many include HbA1c. Very few include fasting insulin. That leaves out the earliest part of the story.

Why glucose looks normal for years

When cells start responding less to insulin, the pancreas compensates by producing more of it. Glucose stays in range because insulin rises to hold it there. This can go on for ten years or more before glucose finally climbs. By then the pancreas is tiring and the window for easy correction is smaller.

A normal glucose with a high insulin is not a normal result. It is a system working harder than it should.

The numbers

Fasting insulin is reported in microunits per millilitre. Lab ranges often run up to 25. We read it more strictly:

• Below 6: what we usually see in lean, active members.
• 6 to 10: worth watching, especially with a growing waist.
• Above 10: we look for insulin resistance and act on it.

We also calculate HOMA-IR, which combines fasting glucose and insulin into one figure. Above 2 is where we start a conversation. Above 3 we treat it as established insulin resistance.

Glucose tells you where you are. Insulin tells you how much effort it takes to stay there.

What disturbs the reading

The sample has to follow a true fast of 10 to 12 hours, water only. A late meal, a hard session the evening before or a poor night can push insulin up by a third. A single high value is a reason to repeat the test, not to diagnose.

When it is worth asking for

Anyone with a waist above 94 cm for men or 80 cm for women, raised triglycerides, a parent with type 2 diabetes or a history of gestational diabetes should know this number.

What moves it

Insulin responds faster than most markers. Losing visceral fat, strength training two or three times a week and moving refined carbohydrate away from the evening usually lower it within three months. Member 0519 went from 14.2 to 7.8 in that time, with fasting glucose unchanged at 92 throughout. On glucose alone, nothing would have looked different.