Atherogenic Index

The triglyceride-to-HDL ratio — a proxy for insulin resistance and small LDL.

What it is

The atherogenic index of plasma (AIP) is calculated as log(Triglycerides ÷ HDL). It is a strong predictor of small dense LDL particle dominance, which is the most atherogenic lipid pattern — often not captured by standard LDL measurement.

Why it matters

People with metabolic syndrome or insulin resistance can have "normal" LDL yet very high cardiovascular risk due to small dense LDL. The atherogenic index flags this pattern. A value above 0.24 suggests dominant small dense LDL. Diet and lifestyle interventions that lower triglycerides and raise HDL improve this ratio.

How to test

Calculated from lipid panel: log(Triglycerides ÷ HDL) in mmol/L.

This information is for educational purposes only. Always discuss testing and interpretation of results with your care team.

Optimal range

Below 0.11

low cardiovascular risk

0.11–0.21

intermediate risk

Above 0.24

high risk — small dense LDL dominant

How often

Each lipid panel.