This study is designed to examine how pregabalin affects parameters of autonomic nerve regulation in correlation with change in pain, anxiety, and depressive symptoms in patients with diabetic neuropathy.

This study is designed to primarily examine how pregabalin affects the autonomic nerve or sympathetic-parasympathetic regulation in patients with diabetic neuropathy and its relationship to neuropathic pain. The goals of this study include (1) assessing the change of parameters of autonomic nerve function such as HRV, RSA, minute ventilation, and changes in objective sleep parameters measured by means of the LifeShirt, upon treatment of pregabalin in comparison to placebo; (2) assessing the symptom change of neuropathic pain upon treatment of pregabalin in comparison to placebo; (3) assessing the change of anxiety symptoms upon treatment of pregabalin in comparison to placebo; (4) assessing the change of depressive symptoms upon treatment of pregabalin in comparison to placebo; (5) assessing the relationship of autonomic nerve function with neuropathic pain at baseline prior to treatment and the correspondences to the study drug; (6) assessing the relationship of autonomic nerve function with anxiety and depressive symptoms at baseline prior to treatment and their correspondences to the study drug; (7) identifying sensitive and reliable parameters of autonomic nerve regulation as predictor(s) of the severity and improvement of neuropathic pain and/or anxiety; and (8) to assess the change in objective sleep parameters (EEG/EOG) by means of the LifeShirt, upon treatment of pregabalin in comparison to placebo

• Drug: Pregabalin
• Drug: Placebo

• Experimental: Pregabalin medication
• Placebo Comparator: Placebo

Inclusion Criteria:

• Outpatients aged 18 years or older
• Meet criteria for diagnosis of diabetic neuropathy
• Average daily pain scores greater than or equal to 4 by Visual Analog Scale
• Ability to give informed consent
• No pregnancy

Exclusion Criteria:

• Patients with clinically significant psychiatric disorders requiring vigorous interventions, i.e., moderate to severe depressive disorder, psychotic disorders, PTSD, OCD, panic disorder, substance abuse, or personality disorders, or active suicidal/homicidal ideations, or past history of active suicidal ideation and/or attempts
• Patients on gabapentin which cannot be discontinued, meaning a dose greater than 1200mg. If a patient is on a dose of gabapentin that is less than 1200mg and he or she is willing to stop taking the medication, he or she can participate in the study. These patients must take the last dose of gabapentin the night before starting the study.
• Patients being non-compliant with diabetic control
• Inability to wear the LifeShirt
• Unable to participate or answer questions using a PDA input device