In HCAR2 knockout T2D mice, the inhibitory effect of 3HB on PPARγ Ser273 phosphorylation was abolished (Fig. 3i, m), suggesting that HCAR2 was essential for 3HB to inhibit PPARγ Ser273 phosphorylation in adipose tissue of T2D mice. This evidence concerns the gene HCAR2 and type 2 diabetes mellitus.