Insulin resistance means your cells respond less well to insulin, so your pancreas produces more to do the same job. That extra insulin circulates for years before blood glucose rises.
This is why a normal HbA1c can sit alongside a real metabolic problem. Glucose stays in range precisely because insulin is working overtime to keep it there.
HOMA-IR estimates that using fasting glucose and fasting insulin together. Roughly: below 1.0 suggests good sensitivity, 1.0 to 1.9 is normal, 2.0 to 2.9 suggests early resistance, and 3.0 or above suggests significant resistance.
Thresholds vary between populations and laboratories, so treat the bands as a guide.
Fasting insulin is not always available, and many standard panels omit it.
The triglyceride-glucose index uses fasting triglycerides and glucose instead, both of which appear on routine tests. It correlates well with more complex measures and is increasingly used in research for exactly that reason.
If you have a recent blood test with a lipid panel, you can probably calculate TyG without any new tests.
Both calculations require a genuine fast: nothing but water for 8 to 12 hours, and the sample taken in the morning.
Illness, poor sleep the night before, and recent heavy exercise all affect the numbers. So does a very low carbohydrate diet in the days beforehand, which can raise fasting glucose through a mechanism unrelated to insulin resistance.
One reading is a snapshot. If a result is borderline, repeating it after a normal week is more informative than acting on a single figure.
Insulin resistance is not only a diabetes question.
In men, it lowers testosterone and is one of the most common reversible causes of a low reading.
In women, it drives the whole PCOS picture, prompting the ovaries to produce more androgens and disrupting ovulation. It also worsens through menopause as body composition changes.
Which means improving insulin sensitivity often improves the hormonal picture without treating hormones directly.
Resistance training has the strongest evidence, because muscle is where most glucose is disposed of. It works independently of weight loss.
Walking after meals, ten to fifteen minutes, measurably blunts the glucose rise.
Losing visceral fat specifically. Waist measurement tracks this better than weight.
Sleep. A few nights of poor sleep measurably reduces insulin sensitivity in healthy people.
Related reading: Menopause and diabetes risk · Testosterone and type 2 diabetes · PCOS explained · Waist-to-height ratio
Educational only, not medical advice. Blood results should be interpreted by a clinician.