In order to evaluate the difference in beta cell mass in women with and without a history of gestational diabetes mellitus (GDM), investigators aim to compare quantitative PET imaging of the pancreas between these groups. Investigators propose to measure uptake of 68Ga-NODAGA-exendin-4 in the pancreatic beta cells of these women as a measure for beta cell mass. Furthermore, investigators aim to compare uptake of the radiolabeled tracer to beta cell function measured by laboratory parameters. These highly relevant data within this at-risk population for type 2 diabetes (T2D) will provide the investigators with more information on the role of beta cell mass in the predisposition for development of T2D leading to better knowledge on the pathophysiology of this disease. This could be of great interest for development of new treatment options.