Alcohol suppresses meal-induced insulin sensitization.

Background: In the fed state, the glucose disposal action of insulin can be attributed in approximately equal part to the direct action of insulin and to a hepatic insulin sensitizing substance (HISS) that acts selectively on skeletal muscle. HISS action is absent in the 24-hour fasted state. The objective of this study was to determine whether alcohol administered with a meal affected meal-induced insulin sensitization (MIS). Methods: Rats were fasted for 24 hours and anesthetized, and insulin sensitivity was evaluated using the rapid insulin sensitivity test (RIST). A liquid mixed meal was injected into the stomach along with diluted alcohol equivalent to 1, 0.25, and 0.125 mL/kg of ethanol. After 90 minutes, a second RIST was carried out, atropine administered, and a third RIST done. A control fed group received no ethanol and a RIST was determined at 90 minutes; then 1 mL/kg ethanol or water was administered and the RIST was tested 1 hour later. Results: Ethanol co-administered with a meal produced a ...