✍️ Written by the MedTestBD Editorial Team · Last reviewed: July 2026
What is the Serum Insulin Test?
The serum insulin test measures the level of insulin — the hormone produced by the pancreas that regulates blood sugar — in the blood. It is most informative when measured alongside a simultaneous blood glucose level. The test helps evaluate how well the pancreas is producing insulin and whether the body is responding to it properly. It is a key test in diagnosing insulin resistance and investigating hypoglycaemia.
Why is the Serum Insulin Test Done?
- To diagnose insulin resistance — a condition where cells do not respond properly to insulin, leading to type 2 diabetes and metabolic syndrome
- To investigate unexplained low blood sugar (hypoglycaemia) — abnormally high insulin with low glucose points to an insulinoma (insulin-producing tumour of the pancreas)
- To evaluate polycystic ovary syndrome (PCOS) — insulin resistance is common in PCOS and drives many of its features
- To assess beta cell function — how well the insulin-producing cells of the pancreas are working
- To guide treatment decisions in patients with type 2 diabetes — particularly whether insulin therapy is needed
Normal Serum Insulin Levels
| State | Normal Insulin Level |
|---|---|
| Fasting insulin (normal) | 2 – 25 µIU/mL (most labs) |
| Fasting insulin (optimal) | Below 10 µIU/mL |
| Insulin resistance (suggested) | Fasting insulin above 15–20 µIU/mL with normal or elevated glucose |
Insulin values must always be interpreted alongside the simultaneous blood glucose level. A high insulin with low glucose strongly suggests an insulinoma. A high insulin with normal or high glucose suggests insulin resistance. There is no single universal cut-off — interpretation depends on clinical context and the specific assay used.
How to Prepare for the Serum Insulin Test
- Fasting for 8–12 hours is required for a fasting insulin test — this gives the most clinically useful baseline
- Only water is allowed during the fasting period
- Inform your doctor about any diabetes medications, insulin injections, or steroids you are taking
- Avoid heavy exercise before the test, as physical activity lowers insulin levels
- Blood glucose is usually measured at the same time for accurate interpretation
Serum Insulin Test Price in Bangladesh
Serum insulin test prices vary between diagnostic centers across Bangladesh. Compare serum insulin test prices on MedTestBD →
⚠️ This information is for general reference only. Always consult a qualified physician before undergoing any medical test.
