SIRT1 and Insulin resistance: These effects appear to be mediated by SIRT1, which is a target of CLOCK and BMAL1, as shown by the finding that (i) Sirt1 knockdown blocks the improvement induced by Clock and Bmal1 overexpression on the palmitate-dependent insulin resistance and (ii) Sirt1 overexpression ameliorates insulin resistance induced by knockdown of Clock or Bmal1.