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There is no one test that can directly detect insulin resistance. Instead, a doctor will look at a patient’s entire clinical picture and may suspect that the patient has insulin resistance if s/he has increased glucose levels, increased levels of triglycerides and LDL and decreased concentrations of HDL. Laboratory tests most likely to be ordered include:
- Glucose. This is usually performed fasting but, in some cases, a doctor may also order a GTT (glucose tolerance test – several glucose tests that are taken before and at timed intervals after a glucose challenge). The goal of glucose testing is to determine whether a patient has an impaired response to glucose.
- A1c. This test reflects average blood glucose levels over the past 3 months by measuring the percentage or amount of haemoglobin that have been glycated, or bound with glucose, in the bloodstream. It is also called haemoglobin A1c, HbA1c, or a glycohaemoglobin test.
- Lipid profile. This measures the HDL, LDL, triglycerides, and total cholesterol. If the triglycerides are significantly elevated, a DLDL (direct measurement of the LDL) may need to be done.
Other laboratory tests that may be ordered to help evaluate insulin resistance and provide additional information include:
- Insulin. The fasting insulin test is variable, but insulin levels will usually be elevated in those with significant insulin resistance. Measurement of insulin concentrations during a GTT, sometimes with more frequent sampling, is occasionally also performed.
- hs-CRP. This is a measure of low levels of that may be done as part of an evaluation of cardiac risk. It may be increased with insulin resistance.
- Insulin tolerance test (ITT) with IV-infusion of insulin, with subsequent measurements of glucose and insulin levels, is not widely used.
- sdLDL. This is a measurement of the number of small dense low-density lipoprotein molecules a patient has. This test is not ordered frequently but may be measured as part of a lipoprotein subfractions test.
- Specific insulin suppression tests, measurement of sdLDL, and an Insulin Tolerance Test (ITT) may also be ordered in a research setting to study insulin resistance but are not generally used in a clinical setting.
Last Review Date: October 25, 2018