PMP22 and diabetes mellitus: The severity of neuropathy was increased in CIDP + DM subjects as indicated by the higher TCNS (13 [9, 16], 11 [7, 14], P = 0.003), greater impairment of lower limb reflexes (P = 0.02) and more elevated lower limb VPT (P = 0.01, P = 0.02).