Final answer:
Vital signs should be repeated every 15 minutes during transport for a patient who is unresponsive with a high blood glucose level, unless the patient's condition changes significantly which would require more frequent monitoring.
Step-by-step explanation:
Given the scenario of a 54-year-old male patient with diabetes who is currently unresponsive with a blood glucose level (BGL) of 425 mg/dL, it's important to frequently monitor his vitals. The correct frequency for repeating vital signs during transport is option 4) Every 15 minutes. This recommended interval allows for timely detection of changes without leading to excessive intervention that could distract from transport or patient care. However, if there are significant changes in the patient's condition, such as a change in mental status or if the initial vital signs are concerning, more frequent monitoring may be warranted.