The purpose of this protocol is to determine if an investigational drug known as LY333531 is effective in treating nerve malfunction in diabetes.

Inclusion Criteria:

• Patients must have type I or type II Diabetes Mellitus.
• Have clinically diagnosed positive sensory symptoms such as numbness, lancinating pain, burning pain, aching pain, allodynia and prickling sensation that have been present not greater than 5 years but stable for 6 months.
• Has a HbA1C less than or equal to 12%. Patients with HbA1C greater than 9% must be insulin therapy.
• Must be 18 years or older.
• Be able to visit the doctor's office approximately 3 times over a maximum of a 6-week period to determine if you can continue in the study.

Exclusion Criteria:

• History of significant liver problems.
• Have poor kidney function.
• Drink an excess of alcohol or abuse drugs.
• Have recently participated or currently participating in a Medical study in which you receive an experimental drug.
• Are a woman and are pregnant or breastfeeding, intend to become pregnant within the next 2 years or a woman not using effective birth control.