• Pain severity for worst pain and night pain as measured by an 11-point Likert scale.
• Clinical Global Impression of Severity scale to measure severity of illness at the time of assessment.
• Patient Global Impression of Improvement scale to measure the degree of improvement at the time of assessment.
• Brief Pain Inventory to measure the severity of pain.
• Sensory Portion of the Short Form McGill pain questionnaire measures severity of 11 pain descriptors.
• Hamilton Depression Rating Scale (17 item) used to assess severity of depression symptoms during the course of therapy.
• Dynamic Allodynia measure to elicit the pain severity to a normally non-painful stimulus.

The purpose of the study is to determine if duloxetine can help patients with painful diabetic neuropathy.

The protocol will assess the efficacy and safety of duloxetine. It will also look at how duloxetine affects quality of life.

• Drug: Duloxetine hydrochloride
• Drug: placebo

Inclusion Criteria:

• Male or female outpatients at least 18 years of age.
• Patients with pain due to diabetic neuropathy in both legs.
• Females must not be pregnant or plan to become pregnant during the study.
• Stable Glycemic control.
• Average mean pain severity score of at least 4.0 as assessed by completion of a daily diary.

Exclusion Criteria:

• You are related to or work for the physician conducting the study or are employed by Eli Lilly and Company.
• You have a severe or serious medical condition that causes you to be hospitalized often; or you have had a kidney transplant or are on current dialysis.
• You have participated in a study for an investigational drug within the last 30 days.
• You have a history of major depressive disorder, generalized anxiety disorder, or alcohol or eating disorders.
• You have a past medical history or diagnosis of mania, bipolar disorder, or psychosis.