The research presented in this book is comprised of two parts. Part A is related to research focused on protein glycation which is one of the major causes of diabetic complications. standard bio-assay was established to screen natural and synthetic compounds to discover new lead molecules with high potency and low toxic effects. More than 1000 compounds were investigated and detailed studies were performed. As a result several promising inhibitors of protein glycation belonging to different classes were identified and their cytotoxic effects were determined for their safer use. Part B of this book is related to receptor-based studies on type-2 diabetes mellitus. In this case we used glucagon and GLP-1 receptors.New mutants of these receptors were prepared by site-directed mutagenesis. These new mutants along with parent DNA were expressed in Human Embryonic Kidney cells which were tested for cAMP (secondary messenger) production. cAMP is responsible for the release of glucose from liver in case of glucagon receptor while in case of GLP-1 receptor cAMP is responsible for the release of insulin. Synthetic compounds were also tested against both receptors for cAMP production.