The study will be part of a philosophiae doctor (PhD) project for one MD PhD student. A PhD-project has to fulfill the requirements of the Medical Schools at VU University, Amsterdam, the Netherlands. In general, a PhD-thesis has to contain at least 5 chapters, consisting of manuscripts published in international peer-reviewed journals. The investigators anticipate that this study will yield sufficient data to meet these criteria. Papers will be written at the end of the study, i.e. second half of 2018, and will be submitted to different relevant international peer-reviewed journals (Diabetes, Diabetes Care, etc.). Authorship of the papers will be determined using the Vancouver criteria for authorship.