A Clinical Trial To Evaluate PF-05089771 On Its Own And As An Add-On Therapy To Pregabalin (Lyrica) For The Treatment Of Pain Due To Diabetic Peripheral Neuropathy (DPN)

• Drug: PF-05089771 150 mg
  
  PF-05089771 150 mg twice daily oral dosing with capsules. Treatment period = 4 weeks.
• Drug: Matched placebo for PF-05089771 150 mg and pregabalin 300 mg
  
  Matched placebo for PF-05089771 150 mg twice daily and pregabalin 150 mg twice daily oral dosing with capsules. Treatment period = 4 weeks.
• Drug: Pregabalin 300 mg
  
  Pregabalin 150 mg twice daily oral dosing with capsules. Treatment period = 4 weeks.
• Drug: PF-05089771 150 mg + Pregabalin 300 mg
  
  PF-05089771 150 mg twice daily oral capsules with pregabalin 150 mg twice daily oral capsules. Treatment period = 4 weeks.

• Experimental: PF-05089771
  
  Intervention: Drug: PF-05089771 150 mg
• Experimental: Placebo
  
  Intervention: Drug: Matched placebo for PF-05089771 150 mg and pregabalin 300 mg
• Experimental: Pregabalin
  
  Intervention: Drug: Pregabalin 300 mg
• Experimental: PF-05089771 + Pregabalin
  
  Intervention: Drug: PF-05089771 150 mg + Pregabalin 300 mg

Inclusion Criteria:

• Men and women aged 18 years to 80 years.
• Diagnosis of Type 2 diabetes mellitlus (T2DM) with current glycosylated hemoglobin A1c (HbA1c) levels of ? 11% at Screening and on a stable antidiabetic medication regimen for at least 30 days prior to randomization.
• Presence of ongoing pain due to DPN for at least 6 months.
• Willing to discontinue protocol-specified prohibited pain medications for DPN throughout the duration of the study.

Exclusion Criteria:

• Painful neuropathies or painful conditions other than DPN that may confound evaluation of pain due to DPN during the study.
• Subjects who have failed previously on pregabalin (at the recommended label dose and for adequate duration) due to lack of efficacy.
• Subjects with any clinically significant medical or psychiatric conditions or clinically significant laboratory test abnormalities.
• Pregnant women, lactating mothers, men with partners currently pregnant, women suspected of being pregnant, and women who wish to be pregnant during the course of the clinical study.