This study is designed to evaluate the ability of Spatial Frequency Domain Imaging (SFDI) to measure perfusion in lower extremities for prediction of both healing and formation of diabetic foot ulcers.

The investigators will perform longitudinal imaging (for 12 months) in two cohorts of subjects

Inclusion Criteria:

I. Will be followed up in clinic on monthly basis for the next 12 months per standard of care II. Belong to one of the two target groups

1. Subjects with an existing diabetic foot ulcer
2. Subjects determined "at risk" for an ulcer

Exclusion Criteria:

1. History of heart failure
2. Rheumatoid arthritis
3. Pregnant or lactating women

Male or female patients at University of Southern California diagnosed with a Diabetic Foot Ulcer