In this discussion paper based on preliminary data, the safety and other quality criteria of ChatGPT-4o-generated exercise plans for patients with type 2 diabetes mellitus (T2DM) are evaluated. The study team created three fictional patient profiles varying in sex, age, body mass index, secondary diseases/complications, medication, self-rated physical fitness, weekly exercise routine and personal exercise preferences. Three distinct prompts were used to generate three exercise plans for each fictional patient. While Prompt 1 was very simple, Prompt 2 and Prompt 3 included more detailed requests. Prompt 3 was optimized by ChatGPT itself. Three coaching experts reviewed the exercise plans for safety and other quality criteria and discussed their evaluations. Some of the exercise plans showed serious safety issues, especially for patients with secondary diseases/complications. While most exercise plans incorporated key training principles, they showed some deficits, e.g., insufficient feasibility. The use of more detailed prompts (Prompt 2 and Prompt 3) tended to result in more elaborate exercise plans with better ratings. ChatGPT-4o-generated exercise plans may have safety issues for patients with T2DM, indicating the need to consult a professional coach for feedback before starting a training program.