Endocrinology, Pediatric Research Institute Sant Joan de Déu, University of Barcelona, Barcelona, Spain. Network Biomedical Research Center of Diabetes and Associated Metabolic Disorders (CIBERDEM), Health Institute Carlos III, Madrid, Spain. Endocrinology and Nutrition, Germans Trias i Pujol Research Institute, Barcelona, Spain. Pediatric Endocrinology, Hospital Dr. Josep Trueta & Girona Institute for Biomedical Research, Girona, Spain. Department of Development & Regeneration, University of Leuven, Leuven, Belgium.