Alzheimer’s disease (AD) and diabetes are among the most common diseases associated with ageing. The pathology of AD is strongly associated with accumulated misfolding proteins that results in neuronal dysfunction within the brain. Diabetes, on the contrary, is characterised by altered insulin signaling that results in reduced glucose uptake, metabolic suppression of energy consuming cells and conversion of glucose to fat in the liver. Despite distinguishing features, these diseases share common elements and may in fact be viewed as fundamentally similar disorders that differ in magnitude of specific traits, primarily affected tissues and time of onset. In this review, we outline the fundamental basis of each of the two diseases and highlight similarities in their pathophysiology. Further ahead we will discuss these features in relation to the development of drugs to treat these two diseases, particularly AD, for which the development of therapeutic chemicals has proven to be particularly difficult. We conclude with comments on efforts to develop a simple organism, Caenorhabditis elegans, as a genetic model to be used to study the systems biology of diabetes and AD.