In the last 40 years or so, we have seen an astounding rise in the prevalence of Type 2 Diabetes Mellitus (DM2) in most western and 'developing' countries. National data suggests a six-fold increase from around 1% of the population in 1980 to over 6% in 2020. There are thought to be nearly 4 million people with the disease in the UK, and close on half a billion affected worldwide. In parts of the USA and China over 10% of the population have DM2. Traditionally thought of as a disease of mid-life and old age, both DM2 and the metabolic markers of future disease are now increasingly being seen in young people, children and even infants. What is happening?  The burden of this disease is huge at all levels - for health care spend and for added risk of other medical problems. Its overall impact on health is at least as great as that of Type 1 Diabetes - it's certainly not the 'mild Diabetes' it was once called. In addition, other than its physical impacts - more than a third of people with DM2 are said to experience psychological problems related specifically to the condition.  In spite of the tidal wave of disease and costs, the response from authorities has been somewhat underwhelming, with non-specific advice to lose weight (move more/eat less) being more or less the only public health guidance.  We now however have a sense of being at something of a crossroads in understanding the science behind DM2 with a more focused approach emerging. Research and practice are challenging the traditional way in which we approach and manage DM2 - and offer too the potential for prevention - at scale. A central tenet of the book is that people can be educated, empowered and supported to control their metabolic health and to prevent, improve and manage DM2. We want to present a fresh and balanced individual take on the science around DM2 with an examination of the belief systems and behaviours that have fuelled its rise. As well as a section looking at mental health problems and DM2, we want to thread psychological and behavioural themes throughout the text.