Diabetes mellitus is a chronic disease and a major public health challenge worldwide. Using data mining methods to aid people to predict diabetes has become a popular topic. In this paper, Bayes Network was proposed to predict patients with developing Type-2 diabetes. The dataset used is the Pima Indians Diabetes Data Set, which collects the information of patients with and without developing Type-2 diabetes. Weka software was used throughout this study. Accurate results have been obtained which proves using the proposed Bayes network to predict Type-2 diabetes is effective.