Fasting glucose

Fasting glucose is the plasma blood-sugar concentration after at least eight hours without caloric intake. It reflects baseline glucose homeostasis driven by hepatic glucose output, β-cell insulin secretion, peripheral insulin sensitivity, and counter-regulatory hormones such as glucagon, with renal glucose handling as a further contributor. Persistently elevated values indicate impaired fasting glucose, prediabetes, or type 2 diabetes, and Mendelian randomization supports a causal effect of higher fasting glucose on coronary disease. Even within the upper-normal range, rising fasting glucose tracks with increased risk, so stable lower-normal values are generally favorable.

Last reviewed: January 15, 2026