A nurse is reviewing the laboratory results of a client who is at risk for developing diabetes mellitus. The nurse should recognize that which of the following results indicates the client meets the criteria for diagnosis of diabetes mellitus?

Choice A reason: A 2-hour blood glucose level of 170 mg/dL following an oral glucose tolerance test is elevated but does not meet the diagnostic threshold for diabetes mellitus. According to established criteria, a 2-hour plasma glucose level of ≥200 mg/dL is required for diagnosis. Therefore, while this result may indicate impaired glucose tolerance, it is not diagnostic. Choice B reason: An HbA1c of 5.5% falls within the normal range. The diagnostic threshold for diabetes mellitus is an HbA1c of ≥6.5%. This value may suggest a risk for future development of diabetes but does not meet the criteria for diagnosis. Choice C reason: A casual (random) blood glucose level of 180 mg/dL is elevated but not diagnostic unless accompanied by classic symptoms of hyperglycemia such as polyuria, polydipsia, and unexplained weight loss. The diagnostic criterion for casual glucose is ≥200 mg/dL with symptoms. Choice D reason: A fasting blood glucose level of 155 mg/dL meets the diagnostic criteria for diabetes mellitus. The threshold for diagnosis is a fasting plasma glucose level of ≥126 mg/dL. This result, if confirmed on a separate occasion, supports a diagnosis of diabetes.