Diabetes mellitus is multifactorial disease of multiple etiology, which is resulted from defects in insulin secretion, insulin action or both. A diabetic foot infection is one of the most feared complications of this disease which presents in different ways such as ulcer, infection and gangrene. Leg amputations begin with a foot ulcer caused by main risk factors such as neuropathy, peripheral vascular disease, foot deformity and trauma. Over the last few years, the use of diagnostic technologies has increased exponentially including immunological parameters in the medical field. With this awareness, there is a rise in the need for improving laboratory diagnostic methods. Traditional laboratory tests to detect diabetic foot infections are no longer adequate; therefore introducing a new parameter Procalcitonin" could be considered as a good discriminative biomarker in diagnosis of the disease as elevated procalcitonin levels strongly predict major amputation in long standing diabetic patients with foot ulceration. This book provides a new biomarker of success for both clinical and microbiological criteria by investigating the type of microbe as well as the severity of infection.