My grandfather graduated from University of Toronto med school while Banting & Best were studying insulin. Even when insulin was more widely available, the goal was to use as little as possible while restricting sugar, flour, grains, sweet fruits, etc. as it was "common knowledge" that these foods and insulin would make people fat. Patients who were "T1 diabetic success stories" would appear in medical journals, looking scrawny but healthy compared to their before insulin photos. The goal was to keep them scrawny ("normal" in the 1920s) and dial back on the insulin if they started getting fat. Even into the 1960s womans' magazine diets still told readers to avoid the white stuff, and it worked! ... until Ancel Keys' theory started reaching the laypeople's newspapers.