Final answer:
The most beneficial diagnostic test to assess the patient's condition is a Neurologic Exam, specifically to assess impaired sensory functions. Other tests include laboratory tests like blood screening for glucose levels.
Step-by-step explanation:
The diagnostic test that will be most beneficial to assess the patient's condition of dementia and metabolic disorders is a Neurologic Exam.
The neurologist might perform an exam to assess impaired sensory functions by asking the patient to follow a target through different positions. This helps to determine any impairments in the sensory systems of the nervous system.
Other diagnostic tests that may be useful in assessing the patient's condition include laboratory tests, such as blood screening for glucose levels and A1C test to measure average blood glucose levels over a period of time.