Final answer:
The nurse should see the client with a critical fasting blood glucose level of 517 mg/dL first, as it indicates a possible hyperglycemic crisis requiring prompt medical attention.
Step-by-step explanation:
The nurse should prioritize seeing the client with a fasting blood glucose of 517 mg/dL (28.69 mmol/L) first. This reading is dangerously high and can signify a severe hyperglycemic crisis which requires immediate medical intervention. The other clients' needs are not as acutely life-threatening and can await treatment after this critical situation is addressed. For context, normal fasting blood glucose levels are generally below 100 mg/dL.
Levels between 100 and 125 mg/dL indicate pre-diabetes, and levels higher than 125 mg/dL can lead to a diagnosis of diabetes mellitus. A glucose tolerance test (GTT) is used to diagnose diabetes in patients with normal or borderline fasting glucose levels. If the patient's pancreas functions normally after ingesting a sugary drink provided during the GTT, their blood glucose levels should return to normal ranges.