The goal of this research is understand if obesity is a major factor for neuropathy development in patients with and without Type 2 diabetes. This study will examine the relationship between weight, metabolism, and nerve function and regeneration.

Peripheral neuropathy causes progressive injury to the longest nerves of the body, starting in the toes, then progressing slowly up the leg. Neuropathy often causes pain, numbness, and weakness if the feet and can lead to reduced mobility, foot ulcers, and even amputation. The most common cause is diabetes, but work at the University of Utah finds that prediabetes and other consequences of obesity, including abnormal cholesterol levels, may be associated with neuropathy. Research has shown that these risk factors may damage nerves and interfere with the ability of nerves to grow back after an injury.

This study aims to

1. characterize peripheral nerve function and cutaneous nerve structure in obese bariatric surgery candidates;
2. evaluate peripheral nerve regeneration capacity (and other nerve function measures) before and after bariatric surgery in obese subjects with no or mild neuropathy;
3. examine the relationship between ectopic lipid accumulation, lipotoxic mediators, neuropathy and regeneration capacity in surgical candidates before and one year after surgery.

Inclusion Criteria:

• Age 18-80 years old
• Subjects must fulfill criteria for bariatric surgery.

Exclusion Criteria:

• History of foot ulceration or neurogenic arthropathy
• Family history of non-diabetic neuropathy in a first-degree family member.
• Presence of any disease known to be associated with peripheral neuropathy including but not limited to vitamin deficiency, toxin exposure, paraproteinemia, heavy alcohol use, hepatitis C, HIV.
• Coumadin use.
• Inability to understand or cooperate with the procedures of the trial.
• Known history of sensitivity to capsaicin products.

Participants will be recruited through bariatric surgery clinics in the local area.