Diabetes mellitus type 2 is a metabolic disorder characterized by high blood glucose due to insulin deficiency or resistance. Alzheimer's disease (AD) is a complex neurodegenerative disease leading to irreversible loss of neurons, intellectual abilities, memory and reasoning. The worldwide prevalence of diabetes and AD in elderly population is a major public health concern. Interestingly, both health issues are unraveling the puzzling links. The clinico-pathological relationship between diabetes and AD has been reported at genomic and proteomic levels. The association of virus infection in type 2 diabetes mellitus and AD has been reported in few recent studies, some have shown direct evidence of virus infection in diabetes and AD while other have shown that diabetes increases the risk of developing AD. This review aims to summarize the association of few common viruses like Hepatitis C Virus and Herpes Simplex Virus-1 which affects both these two age-related devastating diseases. We also discuss the pathological links of Influenza virus, Cytomegalovirus, West Nile virus, Enterovirus, Herpes Simplex Virus-2, Hepatitis viruses in diabetes and Influenza virus, Picornavirus and Borna disease virus in AD. Establishing such relationships and defining their common pathogenesis and patho-physiological mechanisms may lead to new concepts and paths for developing novel preventive strategies and pharmacological treatment options for diabetes and AD. This study may aid in future for the identification of a single or a panel of likely blood-based viral biomarkers for early diagnosis of diabetes and AD with high sensitivity and specificity.