Lidocaine for Diabetic Peripheral Neuropathy

Diabetic peripheral neuropathy [DPN] is caused by diabetes-related metabolic damage to the
sensory nervous system. It affects more than 3 million Americans and is leading cause of
nerve damage-associated pain worldwide. Currently approved drugs such as gabapentin,
pregabalin, and duloxetine provide pain relief only in 1 out of 4 or 5 people with DPN,
pointing to a great need to identify effective therapy for these patients. Recent literature
suggests that certain methods of assessing sensory nerve function in neuropathic pain
patients may provide prediction to individual analgesic response; however, no
placebo-controlled studies have been performed with the primary goal of identifying treatment
response predictors in DPN.

We propose in this study to examine whether sensory testing to determine mechanical pain
threshold [MPT] or heat pain threshold [HPT] will predict the subject's response to IV
lidocaine analgesic therapy. We hypothesize that people with painful DPN who have high MPT or
HPT are more likely to respond to lidocaine treatment. This is a prospective, double blind,
placebo-controlled study with the primary objective of determining whether the results from
the sensory testing predict the response to systemic lidocaine in patients with painful DPN.

Consented subjects will attend a screening visit and two intervention visits, during which
they will undergo sensory testing and receive intravenous lidocaine or placebo infusion in a
cross-over design. At enrollment, each patient will be assigned a study number, which will
match a previously prepared computer-generated list of randomization numbers to determine the
sequence of interventions: lidocaine and then placebo, or vice versa. An unblinded research
nurse coordinator will be assigned to match the study number with randomized treatment
sequence, and this person will prepare the study medications, which will look identical. This
research nurse coordinator will not be involved at any stage at patient assessment or data
analysis. The participants and all other study personnel will be blinded to the treatment
allocation.

Inclusion Criteria:

1. Age ≥18;

2. Diagnosis of Diabetes Mellitus (Fasting Plasma Glucose > 126 mg/dL and/or HbA1C
>6.5%);

3. Distal symmetric pain in lower extremities with duration of more than 3 months;

4. Presence of either numbness or at least 1 sensory disturbance (increased or decreased
sensitivity) in the feet.

5. Spontaneous pain with intensity of ≥ 4 on 0-10 Numerical Rating Scale (NRS).

Exclusion Criteria:

1. Not giving consent to participate in the study;

2. Unable to complete self-report pain questionnaire;

3. History of moderate to severe renal or liver failure;

4. History of other central or peripheral neurologic disorders;

5. History of cardiac arrhythmias;

6. Contraindication to intravenous lidocaine;

7. Pregnancy or lactation.