This study has an initial open-label treatment period of up to 20 weeks with REGRANEX® gel for ulcers of the ankle or foot related to diabetes mellitus. Gel is applied once a day in a thin layer to cover the entire surface of the ulcer; then a non-adherent dressing and gauze are used to cover the gel. If all ulcers are healed during this open-label period, and if they remain healed after 24 weeks of observation, the patient discontinues the study. If one or more ulcers are not healed during the 20 weeks, of if an ulcer recurs or a new ulcer is observed during up to 24 weeks of observation, then the patient enters Double-blind Phase #1 during which neither the patient nor the physician knows whether the study drug or placebo is being applied to the ulcer. This Phase #1 may continue for up to 52 weeks. If one or more ulcers are not healed during 52 weeks of treatment, the patient discontinues the study. If all ulcers are healed during this phase, and if they remain healed after 24 weeks of observation, the patient discontinues the study. If an ulcer recurs or a new ulcer is observed during the observation period following Phase #1 treatment, then the patient enters Double-blind Phase #2 of the study for up to 20 weeks. If the ulcer is healed during Phase #2 treatment, the patient discontinues from the study at that time. If the ulcer remains unhealed after 20 weeks of Phase #2, the study is stopped. Efficacy assessments include the time to complete healing of the ulcer, the incidence of complete ulcer healing, and the reduction in total ulcer area at the end of the study. Safety assessments include the incidence of adverse events throughout the study, changes in clinical laboratory tests (hematology, chemistry, urinalysis), measurement of vital signs at specified intervals, and physical examinations at the start and end of the study. The study hypothesis is that the time to complete healing of diabetic foot ulcers with continued treatment using REGRANEX® is shorter than the time to healing with placebo and that the patients will well tolerate the medication. REGRANEX® gel (or placebo) applied to cover the entire surface of the ulcer, once a day for up to 52 weeks