Fasting and Nonfasting Lipid Levels and Cardiovascular Risk Prediction

This landmark study challenged a longstanding clinical convention: the requirement that patients fast before a lipid blood draw. Using data from 33,000 participants in the Copenhagen General Population Study, it compared lipid profiles under fasting and nonfasting conditions and asked whether the differences mattered for cardiovascular risk prediction.

After normal food intake, LDL cholesterol changed by at most 8 mg/dL and total cholesterol by 8 mg/dL — differences too small to alter clinical decisions in practice. Non-HDL cholesterol, apolipoprotein B, and the apoB/ApoA-I ratio showed essentially no meaningful change with normal meals. Most importantly, nonfasting measurements predicted cardiovascular events as effectively as fasting measurements in the prospective follow-up.

The practical consequence is substantial. Fasting requirements are a real barrier to lipid testing — they require advance scheduling, patient compliance across a half-day fast, and sometimes return visits. If nonfasting measures are clinically equivalent, the barrier is unnecessary and serves no patient benefit. This study was a key driver of the subsequent guideline changes that relaxed fasting requirements for routine lipid testing.

We rate the evidence strong. A large, carefully conducted study that effectively dismantled the scientific rationale for mandatory fasting before routine lipid measurement — with direct, lasting impact on clinical practice.