As Editor-in-Chief of the journal Diabetology, I am pleased to announce the Special Issue "Diabetology: Feature Papers 2021" is now published in book format. Diabetology (ISSN 2673-4540) is an international, peer-reviewed scientific open access journal that provides an advanced forum for studies related to epidemiology, etiology, pathophysiology, pathogenesis, management, complications, and prevention of diabetes, including the molecular, biochemical, and physiological aspects of diabetes. In this Special Issue, "Feature Papers", we aim to publish outstanding contributions in the main fields covered by the journal, which will make a great contribution to the community. This book covers the whole spectrum of diabetology from risk screening, risk markers, pathways of disease in type 1 diabetes and insulin treatment, and management of the disease and comorbidities.