Elderly diabetics tend to have atypical and life menacing infections. The increased susceptibility to infections is partly described by impaired neutrophilic action and impaired T-cell immunity in diabetes. Abnormalities of neutrophils exemplified in vitro are decreased in adherence, chemotaxis, opsonization, and intracellular killing of microorganisms. Cell mediated immune response are diminished with a decrease in proliferative response of T cells to phytohemagglutinin and Staphylococcus aureus. Abnormal delayed hypersensitivity responses are also reported in diabetes. The infections that are accompanied with diabetes are respiratory tract, skin and soft tissue infections and urinary tract infection. Other infections may be fungal infection, hepatitis C virus and periodontal disease. Infections occurring uniquely in diabetics include rhino-orbito-cerebral mucormycosis, acute emphysematous pyelonephritis, emphysematous cholecystitis and malignant otitis externa. All the infections described in this chapter are well explained.