Review Question - QID 214771

A 51-year-old man presents to his primary care physician for his annual physical exam. He says that he started a new diet and exercise program over the last 3 months and has been feeling better than ever. His past medical history is significant for type 2 diabetes, and he was prescribed metformin during the previous visit. He says that he has not taken any of the medication because he wanted to try to manage his diabetes with lifestyle changes first. Laboratory results at the current visit reveal a hemoglobin A1c level of 5.2% compared with 7.6% at the visit last year. Which of the changes shown in Figure A most likely occurred in this patient over the course of his diet and exercise program?