Fasting insulin measures the hormone that moves sugar from the blood into cells.
- Normal range (adults)
- 2–25 µIU/mL (12–150 pmol/L)
- Sample
- Blood
- Fasting
- Yes — 8 to 10 hours without food.
- Also called
- Fasting Insulin, Serum Insulin, Insulin Level, INS
Fasting Insulin normal range
| Group | µIU/mLConventional units: US, South Asia | pmol/LSI units: UK, Europe, Australia, international |
|---|---|---|
| Adults | 2–25 | 12–150 |
Your report may use either unit system; labs in the Gulf often print both. Ranges also vary slightly between laboratories, so the range printed on your own report is the one to go by.
Why is the Fasting Insulin test done?
It is used to look for insulin resistance, often before blood sugar rises, and in investigating low blood sugar.
What does a high Fasting Insulin level mean?
High fasting insulin with normal glucose usually means insulin resistance: your body needs more insulin to keep sugar normal. It is an early warning sign of type 2 diabetes and is linked to fatty liver and PCOS.
Common causes
- Insulin resistance from overweight, especially belly fat
- Inactivity
- Polycystic ovary syndrome (PCOS)
- Diet high in sugar and refined carbohydrates
- Rarely, an insulin-producing tumour (insulinoma)
Diet and lifestyle tips
- Cut sugar and refined carbohydrates
- Eat high-fibre foods: vegetables, legumes, whole grains
- Build muscle with strength exercises twice a week, plus daily walking
- Improve sleep and lose belly fat
What does a low Fasting Insulin level mean?
Low insulin with high glucose points to the pancreas not making enough insulin.
Common causes
- Type 1 diabetes
- Long-standing type 2 diabetes
- Pancreatic disease
Diet and lifestyle tips
- Follow your doctor's treatment plan; insulin may be needed
When should you see a doctor?
Discuss with your doctor alongside fasting glucose and HbA1c.
Last updated
This page is for general education and is not a diagnosis. Normal ranges differ between laboratories, so always compare your result with the reference range printed on your own report, and discuss abnormal results with your doctor.