We read with interest an article by Yoon et al. published in The Korean Journal of Pain [1]. This article describes a case of disseminated herpes zoster in immunocompetent elderly patient with previous medical history of diabetes mellitus. Although disseminated herpes zoster is common in the immunocompromised patient, it is a rare clinical finding in the immunocompetent patient. The reactivation of varicella-zoster virus (VZV) occurs with the decline of VZV-specific cell-mediated immunity. Studies have shown increased incidence of herpes zoster incidence in diabetic patients [2,3]. Furthermore, Okamoto et al. compared VZV-specific immunity of patients with diabetes mellitus and healthy individuals and found that patients with diabetes mellitus had significantly lower cell-mediated immunity to VZV than did healthy individuals [4]. They suggested that the increased risk for herpes zoster among patients with diabetes mellitus may be related to decreased VZV-specific cell-mediated immunity. Although more evidence is needed to find the exact mechanism by which diabetes mellitus affects VZV-specific cell-mediated immunity, physicians should be aware that diabetes mellitus may be a condition compromising the immune competency of the patient against VZV infection.