Lab test

Fasting Insulin Test

A fasting insulin test measures the amount of insulin in the blood after a period of not eating.

Typical price

From $29

Results

1-3 business days

Preparation

See preparation notes below

Sample

Blood draw or sample collection at a local center

A fasting insulin test measures the amount of insulin in the blood after a period of not eating. Insulin is the hormone that moves glucose from the blood into cells, and the fasting level can help assess how sensitive the body is to insulin. Clinicians may order it when insulin resistance is suspected, when evaluating metabolic syndrome or polycystic ovary syndrome, or when investigating low blood sugar. It is often interpreted together with a fasting glucose level. Fasting insulin is a supportive measurement, not a diagnosis, and is reviewed by a healthcare provider.

• Insulin (fasting) The concentration of insulin in the blood after fasting, used to assess insulin production and sensitivity.

• People with suspected insulin resistance or metabolic syndrome
• Individuals with polycystic ovary syndrome or difficulty with weight management
• Those being evaluated for episodes of low blood sugar
• People with a family history of type 2 diabetes
• Anyone whose healthcare provider wants to assess insulin sensitivity

• Fast for about 8 to 12 hours before the blood draw; water is allowed
• A fasting glucose test is often drawn at the same time for comparison
• Tell the lab about diabetes medications, since they can affect insulin levels
• Avoid strenuous exercise right before the test unless instructed otherwise

A high fasting insulin level may suggest insulin resistance, in which the body needs more insulin to manage blood sugar. A low fasting insulin level may suggest reduced insulin production. Because insulin acts together with glucose, the two are often interpreted as a pair, and calculated indices can estimate insulin sensitivity. Fasting insulin is a supportive measurement rather than a diagnosis. Discuss your result with a healthcare provider, who can interpret it in the context of your glucose level and overall health.

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