Major depression and bipolar disorder are chronic enduring serious mental illnesses (SMI) with devastating effects on psychosocial functioning and may culminate in suicide. Over the past years, it has become apparent that subjects with these conditions can also develop the metabolic syndrome, which is a series of obesity-related physical conditions with an endocrine basis. This book brings together reviews that help put into context exactly why subjects with SMI develop obesity, prediabetic status, overt type 2 diabetes mellitus and related cardiovascular events. The relationship between prolactin and bone mineral density in subjects under medical treatment and the underlying dopaminergic mechanisms as well as the immunological changes occurring as an integral part of SMI and their effects on endocrine function are discussed and reviewed. Psychiatrists, diabetologists, cardiologists, family practitioners, public health physicians as well as basic science researchers will find valuable guidelines when screening for type 2 diabetes mellitus and cardiovascular disease in SMI.