Exogenous d-β-hydroxybutyrate lowers blood glucose in part by decreasing the availability of L-alanine for gluconeogenesis

In this crossover study, 10 healthy volunteers fasted for 24 hours and then ingested 25 g of d-beta-hydroxybutyrate as a ketone ester drink on two visits, once with an additional 2 g of L-alanine. The ketone ester raised blood beta-hydroxybutyrate to 4.52 mmol/L, lowered glucose from 4.97 to 3.77 mmol/L, and lowered L-alanine from 0.56 to 0.41 mmol/L. L-alanine supplementation raised blood L-alanine by 0.68 mmol/L and did not significantly affect beta-hydroxybutyrate, L-glutamine, free fatty acids, lactate or C-peptide. It significantly attenuated the ketosis-induced drop in glucose from 28 percent to 16 percent (p < .01).