PMP22 and diabetes mellitus: On the molecular biology level, the serum IGF-1 concentration of DM rats was significantly reduced, and the expression of IGF-1, p-IGF-1R, P0, and PMP22 protein and corresponding mRNA in the sciatic nerve of the DM rats was also inhibited, suggesting that the peripheral nerve tissue myelin regeneration disorder in DM rats was associated with the inhibition of IGF-1 and its receptor IGF-1R.