Braun A, Sämann A, Kubiak T, Zieschang T, Kloos C, Müller UA, Oster P, Wolf G, Schiel R. Effects of metabolic control, patient education and initiation of insulin therapy on the quality of life of patients with type 2 diabetes mellitus. Patient Educ Couns. 2008 Oct;73(1):50–9. doi: 10.1016/j.pec.2008.05.005. PMID: 18583087.