OPRM1 and diabetic neuropathy: Early systemic hG-CSF treatment attenuates neuropathic pain after peripheral nerve injury through activation of mu opioid receptors on the injured nerve [54], induces swift pain relief in diabetic foot gangrene in humans [55], and promotes a dramatic therapeutic effect on a rodent model of diabetic neuropathy, which was attributed, at least in part, to the actions of bone marrow-derived cells [56].