Comparing measured and reported change in gastrointestinal symptoms after initiation of metformin treatment: a questionnaire validation study. - af Geijerstam, Peder; Wenemark, Marika; Daka, Bledar; Jansson, Stefan; Kalin, Kenny; Rolandsson, Olov; Rådholm, Karin (Scandinavian Journal of Primary Health Care, 2025)