1. Galactose utilization after intravenous injection was measured in fed and fasted man together with changes in blood glucose, lactate and insulin.
2. Feeding did not alter blood galactose half-life.
3. The mean increases in blood glucose and lactate were greater in the fasted subjects but their concentrations reached similar values in both fed and fasted states.
4. Plasma insulin increased after galactose in the fasted state, but there was no change in the fed state, indicating that galactose is not insulinogenic.
5. After an intravenous galactose load in the fed state insulin appears to inhibit hepatic glucose release.
6. An intravenous galactose test might be a useful measure of hepatic glucose release under different physiological and pathological conditions.