High insulin (hyperinsulinaemia)

High insulin levels usually indicate that the body is producing extra insulin to keep blood glucose in range, a hallmark of insulin resistance.
This is commonly seen in type 2 diabetes or pre‑diabetes, where the body cannot use insulin effectively. Iimpaired insulin function leads to rising blood glucose levels and eventually type 2 diabetes if untreated. Elevated insulin is therefore a marker of metabolic dysfunction and increased future diabetes risk.

Low insulin (hypoinsulinaemia)

Low insulin levels generally indicate insufficient insulin production.
In type 1 diabetes, the body cannot produce insulin, leading to high blood glucose and the need for lifelong insulin replacement. Low insulin in someone without known diabetes can signal evolving type 1 diabetes, pancreatic dysfunction, or advanced type 2 diabetes where insulin production has declined.