Higher than usual insulin levels in the blood.
How the situation develops
Insulin is the hormone that helps cells take up glucose from the blood to use as energy. When cells become less responsive to insulin, a situation called insulin resistance, the pancreas reacts by releasing more insulin to keep blood glucose normal. Over time, this excess insulin stays high in the blood, and that is what hyperinsulinaemia means. At this stage blood glucose may still look normal, because the extra insulin is managing to keep it in range. For that reason the situation usually develops slowly, may not cause obvious symptoms early on, and is sometimes noticed only when testing is done for another reason.
Why it matters for PCOS
Hyperinsulinaemia is common in PCOS, although it does not affect every woman. High insulin levels can raise androgen production by the ovaries and lower SHBG, the protein that binds hormones in the blood. When SHBG falls, more androgen circulates in its active, free form. These effects can contribute to irregular cycles and androgen signs such as acne and hirsutism in some women. This is one reason the hormonal and metabolic sides of PCOS often appear to be connected. Its link with insulin response is explained further on the insulin resistance page.
How it relates to insulin resistance
Hyperinsulinaemia and insulin resistance are often mentioned together, but they are not the same thing. Insulin resistance refers to cells responding less, while hyperinsulinaemia is the high insulin that builds up as the body compensates. In other words, one describes the cause and the other describes an effect that can be measured in the blood. Understanding this difference matters, because the markers a doctor uses may show only one aspect at a time. One can be present without the other in certain situations, so a doctor looks at the whole picture rather than a single marker.
When to talk to a doctor
Hyperinsulinaemia is not part of the PCOS diagnostic criteria, and a doctor reads it alongside cycle pattern, androgen signs, and other test results, as discussed in what is PCOS. Because it rarely causes obvious symptoms, it is usually identified through a doctor’s assessment rather than felt directly. Any decision about testing, medicine, or supplements should be made with a doctor based on your own situation, and not on a single test result alone.
This glossary is education, not diagnosis. For your own situation, ask a doctor or pharmacist.