We used hepatic balance and tracer (3H-glucose) techniques to examine the impact of “breakfast” on hepatic glucose metabolism later in the same day. From 0-240 min, 2 groups (n=9 each) of conscious dogs received a duodenal infusion of glucose (GLC) or saline (SAL), then fasted from 240-360 min. Three dogs from each group were euthanized for tissue collection at 360 min. From 360-600 min, the remaining dogs underwent a hyperinsulinemic (4x basal) hyperglycemic clamp (arterial blood glucose 146±2 mg/dL) with portal glucose infusion. The total glucose infusion rate was 14% greater in GLC vs SAL (AUC360-600min 2979±296 vs 2597±277 mg/kg, respectively). The rates (mg.kg-1.min-1) of hepatic glucose uptake (5.8±0.8 vs 3.2±0.3) and glycogen storage (4.7±0.6 vs 2.9±0.3) during the clamp were markedly greater in GLC vs SAL. Hepatic glycogen content was ≈50% greater, glycogen synthase activity was ≈50% greater, glycogen phosphorylase activity was ≈50% lower, and the amount of p-glycogen synthase was 34% lower, indicating activation of the enzyme, in GLC vs. SAL. Thus, morning GLC primed the liver to extract and store more glucose in the presence of hyperinsulinemic hyperglycemia later in the same day, indicating that breakfast enhances the liver’s role in glucose disposal in subsequent same-day meals.
- Received October 27, 2016.
- Accepted January 27, 2017.
- © 2017 by the American Diabetes Association.