**1.1 Overview of diabetes: incidence, intensity and implication of innovative therapies**

Diabetes is one of the fastest growing health challenges of the twenty-first century, with the number of adults living with diabetes having more than tripled over the past 20 years [1]. Most forms of diabetes witness hyperglycemia, which has its pathogenesis focally in the islet β cell. Known diabetics (diagnosis confirmed) as well as those who are at-risk of developing the disease exhibit impairment or loss of propeptide processing and secretory function. For the purpose of prediction, diagnosis or prognostics, biomarkers and genetics are used to understand the state of a biological process, severity of a pathological condition, and response to an intervention. This holds true for both research and clinical settings. The current chapter will focus on the potential utility of genetic markers, circulating molecules, and immune cell phenotyping as β cell's biomarkers of cellular function. How these biomarkers complement

the assessment of β-cell secretory function is also interestingly explained. Having essayed the vitality of islet β cell, the chapter will also touch upon the possible implications of its loss. And henceforth, the β-cell secretory function could itself be considered as a biomarker. However, steadfast advances in the field have set the stage for stem cell-based approaches to take over in the near future. Generation of functional pancreatic islet cells using Human pluripotent stem cells (PSCs), including human embryonic stem cells and induced pluripotent stem cells, are promising cell sources in regenerating pancreatic islets, and this will become possible based on the substantial progress made over the past years. The forthcoming decade will probably witness research driven towards the molecular mechanisms of PSC-derived islet cells and their entailed use in experimental disease treatment. Therapeutic efficacy and safety considerations of patient PSC-derived islet cells and transplantation delivery systems should also be researched upon.
