The various insights into glucose tolerance are highlighted in this elaborative book with the help of up-to-date information. The development from normal glucose tolerance (NGT) to type 2 diabetes is associated with the involvement of transitional stages of impaired fasting glucose (IFG) and impaired glucose tolerance (IGT), also known as pre-diabetes. The pathophysiology fundamentally associated with the growth of these glucose metabolic changes is caused by multiple factors, resulting in a change responsible for the balance between insulin sensitivity and insulin secretion. Our understanding of the molecular basis of the signalling pathways monitoring the numerous physiologic outcomes of insulin is gradually increasing. New substrates and signalling molecules have been acknowledged and prospective methods engaged in the pathophysiology of type 2 diabetes have been discovered. This book elucidates the existing state of information on the pathophysiology underlying the development from normal glucose tolerance to type 2 diabetes and therapeutic improvements in the glycaemic control in pre-diabetic and diabetic states.