What is insulin?

Insulin is a hormone—a chemical messenger—made by your pancreas, a gland near your stomach. Its job is to help your body use sugar (glucose) from the foods you eat. Insulin acts like a key: it unlocks your cells, allowing them to take in sugar from your blood to use as energy.

If insulin isn't working well, or if there's not enough insulin, sugar stays in your blood instead of being absorbed by your cells. Over time, this can cause health issues like diabetes or heart disease.

Why test insulin?

Testing insulin levels helps us understand how your body handles sugar. If insulin levels are too high or too low, it might mean your body is struggling to manage sugar effectively. Knowing this can help us catch problems early—long before blood sugar tests become abnormal.

Why test insulin when you're fasting?

A fasting insulin test means we measure your insulin level after you haven't eaten overnight, usually about 8–12 hours. This gives us a baseline picture of your insulin levels without food influencing the results.

If your fasting insulin is high, it could mean your body is working too hard to control blood sugar (a condition called insulin resistance), even if your blood sugar is still normal.

If your fasting insulin is low, it might indicate your body isn't making enough insulin.