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Beaumont Laboratory

Insulin Level

Insulin, Antrim #15548, EPIC: LAB5811, SOFT: INSUL


The patient should fast overnight prior to specimen collection.

Specimen Collection Criteria

Collect: One Gold-top SST tube.

Physician Office/Drawsite Specimen Preparation

Let specimen clot 30-60 minutes then immediately centrifuge to separate serum from cells. Transfer serum to a plastic aliquot tube and refrigerate (2-8°C or 36-46°F) immediately. (Minimum Serum: 0.5 mL)

Preparation for Courier Transport

Transport: Serum aliquot tube, refrigerated (2-8°C or 36-46°F). (Minimum Serum: 0.5 mL)

Rejection Criteria

  • Lipemic, icteric, or grossly hemolyzed specimens.
  • Samples left on the clot at room temperature.
  • Samples subjected to repeated freeze/thaw cycles.


Specimen Stability for Testing:

Centrifuged SST Tubes and Microtainers® with Separator Gels
Room Temperature (20-26°C or 68-78.8°F): 2 hours
Refrigerated (2-8°C or 36-46°F): 7 days
Frozen (-20°C/-4°F or below): Unacceptable

Red-top Tubes and Microtainers® without Separator Gels
Room Temperature (20-26°C or 68-78.8°F): 2 hours
Refrigerated (2-8°C or 36-46°F): Unacceptable
Frozen (-20°C/-4°F or below): Unacceptable

Serum Specimens (Pour-Overs)
Room Temperature (20-26°C or 68-78.8°F): Unacceptable
Refrigerated (2-8°C or 36-46°F): 7 days
Frozen (-20°C/-4°F or below): 3 months

Specimen Storage in Department Prior to Disposal:

Refrigerated (2-8°C or 36-46°F): 7 days


Farmington Hills Chemistry Laboratory.
Royal Oak Special Testing Laboratory.


Monday - Friday.
Results available in 2 business days.

Reference Range

Less than 34 microIU/mL (fasting).

Test Methodology

Chemiluminescent Immunoassay.


Individuals who are significantly overweight have fasting insulin levels that are somewhat higher than those for adults of normal weight.

Patients undergoing insulin therapy may form anti-insulin antibodies that are capable of interfering with this assay.

Insulin levels obtained during a glucose tolerance test appear to have some prognostic value in predicting the benefits of insulin therapy and the likelihood of progression to insulin-dependence and the complications characteristic of diabetes.

Clinical Utility

Insulin assay is used for the quantitative measurement of insulin in serum. This test is used as aid in the diagnosis of insulin-producing neoplasms (islet cell tumor, insulinoma), pancreatic islet cell hyperplasia, to evaluate hypoglycemia, and to evaluate insulin production in diabetes mellitus.

Insulinoma is a rare, islet-cell tumor with insulin hypersecretion. Nintey percent of these tumors are benign. Patients with insulinoma present with hypoglycemia that is the result of the inappropriate secretion of insulin by the tumor. Plasma insulin concentrations decrease progressively in normal fasting patients. Patients with an insulinoma present with high insulin levels and hypoglycemia.

Plasma insulin-to-glucose ratios are also purportedly useful to diagnose insulinoma (1). There are two alternatives. The simple ratio is defined as:

Plasma insulin (microIU/mL)
Plasma glucose (mg/dL)

A simple ratio greater than 0.3 suggests insulinoma.

The "amended" ratio is defined as:

Plasma insulin (microIU/mL) X 100
Plasma glucose (mg/dL) - 30

An amended ratio greater than 50 suggests insulinoma.


  1. Fajans SS, Floyd JC. Fasting hypoglycemia in adults. N Eng J Med 1976;294;766.

CPT Code


Test Codes

Antrim #15548, EPIC: LAB5811, SOFT: INSUL

Last Updated


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UroVysion® is a registered trademark of Abbott Laboratories. ThinPrep® is a registered trademark of Hologic, Incorporated.

This directory currently reflects information only for specimens collected and/or processed at the Farmington Hills, Grosse Pointe, Royal Oak, and Troy campuses.