Is There an Insulin Resistance Test?

Is there an insulin resistance test you can take to find out whether you're insulin resistant? Insulin resistance is a condition where insulin receptors on cells don't respond well to the insulin the pancreas makes. Thus, the pancreas has to pump out more insulin to get glucose into cells. Insulin resistance is linked with a high risk of cardiovascular disease and type 2 diabetes.

An Insulin Resistance Test?

There is a test called the insulin tolerance test that can measure insulin sensitivity, but it's not widely used because it's time consuming and expensive. It involves giving a person an IV infusion containing insulin and measuring the amount of glucose and insulin they make in response. It's mostly used in research settings.

There are other insulin resistance tests used in research settings, including the "gold standard" - the euglycemic clamp method, but these are generally not practical to administer in clinical practice, because most take several hours to carry out.

One test that gives useful information for diagnosing insulin resistance is a fasting insulin level and c-peptide level. When the pancreas makes insulin, a molecule of c-peptide is released for each molecule of insulin made. If levels of both insulin and c-peptide are elevated during fasting, it's a pretty good indication that there's insulin resistance.

The oral glucose tolerance test is also helpful as an insulin resistance test, but it, too, is not used very often due to the expense and time involved.

You Don't Always Need an Insulin Resistance Test to Make the Diagnosis

Most doctors use laboratory tests and a patient's history to diagnose insulin resistance. On lab testing, doctors look for high triglyceride levels, low HDL and elevated LDL levels of the small dense type as signs of insulin resistance. They also look for abdominal obesity and an elevated blood pressure as red flags for insulin resistance. Other tests that can be helpful are measuring c-reactive protein levels and fibrinogen levels in the blood.

Insulin Resistance Test: The Bottom Line?

The best insulin resistance tests are not used in practice due to the expense and time involved - but doctors use other laboratory studies to look for this condition such as fasting insulin and c-peptide levels, lipid levels, c-reactive protein and fibrinogen. Combine this with a good history and physical exam - and you can get a good idea of whether a person is insulin resistant or not.

References:

E-medicine. "Insulin Resistance"

The Jewish Hospital. "Insulin Resistance and Hyperinsulinemia"

Diabetes Essentials. Fourth Edition. 2009.