Definition

Insulin is a hormone produced by the pancreas that allows glucose in the blood to enter the cells for energy. The test measures the concentration of insulin in the blood.

Purpose

Investigation of low blood sugar (hypoglycemia), diagnosis of insulin resistance, guiding treatment decisions in type 2 diabetes, monitoring the function of pancreatic islet cell transplants.

Results

Insulin is not interpreted on its own but together with glucose:

InsulinGlucoseInterpretation
HighNormal/HighInsulin resistance
High/NormalLowHypoglycemia due to excess insulin, pancreatic tumor, Cushing's syndrome or insulin overdose
LowHighThe pancreas cannot produce enough insulin, type 1 diabetes or pancreatitis

Normal Values

Laboratory-specific.

Risks and Limitations

Preparation is required:

  • 8 to 12 hours of fasting
  • Biotin supplements must be stopped at least 1 day before the test (biotin interferes with many laboratory tests, a frequently overlooked detail)

Related Tests

C-Peptide

C-peptide is an amino acid chain formed during the pancreas's production of insulin.

Go to term →

HbA1c (Glycated Hemoglobin)

Measures, as a percentage, how much of the hemoglobin in red blood cells is coated with glucose (sugar). Because red blood cells live for about three months, this test reflects

Go to term →

OGTT (Oral Glucose Tolerance Test)

A test that shows how well the body moves sugar from the blood into the tissues. A fasting blood sample is drawn, a sugary liquid is given to drink, and a second blood sample

Go to term →

Other related tests not yet in the glossary: often ordered together with insulin, because C-peptide stays in the blood longer than insulin, it reflects the pancreas's insulin production more accurately. Also Glucose.