SDR9C7 and type 2 diabetes mellitus: Therefore, we measured the expression of cardiac RDH10, a rate-limiting enzyme in retinol metabolism that plays an important role in converting Rol to atRA, and found that as heart function shifted from compensated to decompensated, cardiac RDH10 expression increased and then decreased in db/db mice (Supplementary Fig. 3a, b and d) while we found a significant decrease in the activity of RDHs in the myocardium of db/db mice (Supplementary Fig. 3c)A severe reduction in cardiac RDH10 was also found in T2DM patients (Supplementary Fig. 3d).