How can insulin resistance be measured?

There are many ways^[1] to measure insulin resistance. The gold standard is the euglycemic hyperinsulinemic clamp. In this technique, insulin is infused into a vein to reach a constant level in the blood. Because insulin is being pumped into the blood, the person has artificially high insulin, or hyperinsulinemia. Simultaneously, glucose is also infused at a varying rate until the blood glucose level stabilizes at a normal level. When a person’s blood glucose is normal, it is called euglycemia (the Greek root “eu-” means “good”). At this point, the rate of glucose infusion exactly equals the amount being taken up by the body’s tissues, which is a direct measure of insulin sensitivity. The more glucose that has to be infused to maintain euglycemia, the more it’s being taken up, meaning the tissue is more sensitive to insulin.

The problem with this technique is that it takes a couple of hours to complete and is relatively expensive. In response, lower cost and easier to use methods of estimating insulin resistance have been developed. Two major methods are HOMA-IR and QUICKI. Both require only a single blood draw in order to measure fasting glucose and C-peptide, a byproduct of insulin synthesis. These values are then plugged into an equation that estimates insulin sensitivity. However, these estimations aren’t perfect.