Taken together, these findings indicate that IGFBP-2 might be a new target of metformin action in diabetes and the metformin-AMPK-Sirt1-PPARα-IGFBP-2 network may provide a novel pathway that could be applied to ameliorate metabolic syndromes by controlling IGF-1 bioavailability. This evidence concerns the gene PPARA and diabetes mellitus.