Finding the right tests…
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Emergency services available 24 x 7
Finding the right tests…
Hormonal
Insulin-F checks the amount of insulin in your blood after an overnight fast, usually 8 to 12 hours without food. Insulin is the hormone that moves glucose from your bloodstream into your cells for energy, and this fasting reading is one of the standard ways doctors screen for insulin resistance, alongside your fasting glucose. It's also used to investigate unexplained low blood sugar, guide treatment decisions in type 2 diabetes, and check how well a transplanted pancreas or islet cells are working. On its own, though, fasting insulin can miss insulin resistance in some people, particularly women with PCOS, which is why it's sometimes paired with a post-meal reading.
The test measures insulin circulating in your blood after a fasting period, typically 8 to 12 hours. Your doctor reads it together with your fasting glucose: high insulin with normal or slightly high glucose can suggest insulin resistance, high insulin with low glucose can suggest excess insulin production, and low insulin with high glucose can suggest the pancreas isn't producing enough.
Insulin is the hormone your pancreas releases to move glucose from your blood into your cells. Insulin-F measures this hormone specifically after a period of fasting, which removes the effect of a recent meal and gives a baseline reading.
- Working out the cause of low blood glucose (hypoglycemia) - Screening for insulin resistance, often alongside fasting glucose - Guiding treatment decisions in type 2 diabetes - Investigating suspected PCOS, alongside other hormone tests - Checking how well a pancreas or islet cell transplant is functioning
Your doctor interprets fasting insulin together with fasting glucose, not alone. Raised insulin with normal or borderline glucose often points toward insulin resistance, where your cells need more insulin than usual to respond normally. Raised insulin with low glucose can suggest your body is producing too much insulin. Low insulin alongside high glucose suggests your pancreas may not be making enough, which is relevant in type 1 diabetes and some cases of pancreatitis.
Fasting insulin can look normal even in some people who do have insulin resistance, particularly in women with PCOS. Research has found that post-meal insulin testing catches many more cases than fasting insulin alone. Ask your doctor whether a post-prandial insulin test (Insulin PP) would add useful information in your case.
Yes, Insulin-F requires fasting, typically for 8 to 12 hours before the blood draw. Confirm the exact timing with your doctor or the centre when you book.
A high fasting insulin, especially alongside normal or slightly raised glucose, can suggest insulin resistance, where your cells don't respond to insulin as well as they should. Your doctor will interpret it alongside your glucose result and symptoms.
Yes, fasting insulin can look normal in some people who do have insulin resistance, particularly in PCOS. That's why doctors sometimes add a post-meal insulin test for a fuller picture.
This page is general information about the test, not medical advice. Your own report's reference ranges apply — please discuss your results with your doctor.
Together, they show how your body handles insulin both at rest and after a meal, which can catch cases that a fasting test alone would miss. Your doctor will decide if both are needed for your situation.
Some medicines and supplements, including biotin, can affect insulin test results. Tell your doctor what you're taking before the test and follow their specific instructions.
Reference ranges vary by lab and testing method, so there's no single universal number. Your report will list the specific range used by that laboratory, and ranges vary by lab, so ask your doctor to explain what your result means.
A low fasting insulin, especially alongside high glucose, can suggest your pancreas isn't producing enough insulin, which is relevant in type 1 diabetes and some other conditions. Your doctor will investigate further if this pattern shows up.