The urinary tract is the principal site of infection in diabetics. A changed bacterial adhesion to the uroepithelium, partly as a result of a changed and lowered Tamm Horsfall Protein, and granulocyte dysfunction, possibly as a result of an abnormal intracellular calcium metabolism, are involved in the pathogenesis of urinary tract infections in diabetics. The main risk factors for bacteriuria in female diabetics are more advanced age and more frequent sexual intercourse. Diabetic patients run an increased risk of complications of urinary tract infection. If a symptomatic infection exists, the treatment of choice is antibiotics which can reach high tissue levels. It is not clear if asymptomatic bacteriuria needs medical treatment.