Efficacy of Inhaled Cannabis in Diabetic Painful Peripheral Neuropathy

The purpose of this study is to determine if vaporized cannabis is effective as an analgesic for the treatment of painful diabetic neuropathy.

Neuropathic pain is caused by an insult to the nervous system and accounts for 25-50% of all pain clinic visits. Excluding low back pain, diabetic peripheral neuropathy is the most common neuropathic pain syndrome with an estimated prevalence of 600,000 cases in the United States. There are only 5 medications approved by the FDA for the treatment of neuropathic pain with only 2 out of the 5 approved for the treatment of diabetic peripheral neuropathy. Currently, there is a desperate need for more therapeutic agents for the treatment of neuropathic pain. We propose to use painful diabetic peripheral neuropathy (DPN) patients to study the efficacy of inhaled cannabis on neuropathic pain. We will enroll 20 subjects with each subject acting as their own control; receiving both placebo and three doses of inhaled aerosolized cannabis (low, medium, and high) in random order each separated by at least two weeks. Subjects will be assessed for reduction in pain, changes in normal sensation, changes in cognition, and effects of cannabis on experimentally induced pain.

Eligibility Criteria:
Inclusion Criteria:

* Willing and able to provide informed consent
* History of diabetes mellitus type 1 or type 2 who have stable glycemia and are maintained by diet or a stable regimen of diabetic therapy for at least 12 weeks prior to screening
* Painful diabetic peripheral neuropathy for at least 6 months prior to screening with symmetrical onset confirmed by neurological exam and a score of at least 3 on the investigator section (physical exam) of the MNSI (Michigan Neuropathy Screening Instrument) at screening.
* Subject has a pain rating of at least 4 on the 11 point Numeric Pain Scale.
* Patient is acceptable for enrollment as determined by the Investigator from the medical history, physical exam finding, 12 lead ECG findings, and clinical laboratory test results.
* HbA1C\<11%.
* For female patients, a negative urine pregnancy test

Exclusion Criteria:

* Active opportunistic infections or opportunistic malignancies requiring acute treatment
* Current or past cannabis abuse/dependence, or current other psychoactive drug use disorder (e.g. opioids, methamphetamine, cocaine, alcohol)
* Presence of significant cardiac or pulmonary disease (e.g., tuberculosis, asthma)
* Pregnancy as ascertained by a self-report and a mandatory commercial pregnancy test before any marijuana or placebo consumption condition.
* Current serious mental illness--e.g. bipolar disorder, schizophrenia, or other psychotic disorder
* Other medical conditions that may lead to peripheral neuropathy
* Females who are pregnant or planning pregnancy.
* Females of child bearing potential not using a reliable means of birth control.
* Lower extremity amputations other than toes. Patients must not have phantom pain from amputated toes.
* Other painful conditions or pain of vascular origin that may confound the assessment of PDN.
* Subjects with unstable blood glucose level (Fasting\< 70mg/dL or random blood glucose level \> 250 mg/dL)