I have diabetes, am i more susceptible to ecthyma gangrenosum?

To a certain extent: Ecthyma gangrenosum is a skin lesion that manifests during a severe pseudomonas infection that has spread to the bloodstream. Pseudomonas infections of this kind rarely happen in patients that are not severely immunocompromised, but can occur if a wound gets infected. Patients with diabetes do tend to get wound infections more readily, esp if they do not follow proper prevention and wound care.

Yes: Diabetes increases the risk of infection, especially when blood sugar levels are out of control. The best way to lower your risk is to keep your blood sugars in a normal, healthy range. There isn't much research into diabetes and the specific disease you mention (ecthyma gangrenosum) however, the likelihood of uncontrolled diabetes increasing the risk is high. http://flip.dlvr.it/rw.