CNR1 and diabetes mellitus: Our hypotheses were: (1) microglia activation occurs in spinal cords and thalami of mice with diabetes and painful diabetic peripheral neuropathy; (2) CB2 receptor agonists would prevent microglial activation, ameliorating the development of neuropathic pain; (3) CB1 agonists would benefit pre-existing neuropathic pain in animals with long standing diabetic peripheral neuropathy and associated pain.