Which diagnostic test is most appropriate for a previously healthy woman with elevated blood pressure and random glucose suggestive of diabetes risk?

In this scenario, the most appropriate diagnostic test is the fasting plasma glucose level. This test is essential for evaluating a patient for diabetes, particularly in someone who presents with elevated blood pressure and random glucose levels that suggest increased diabetes risk.

The fasting plasma glucose test requires the patient to refrain from eating for at least 8 hours, providing a reliable measure of baseline glucose levels without the influence of recent food intake. In this case, since the woman is previously healthy but exhibits elevated blood pressure and glycemic indicators, assessing her fasting glucose levels can help confirm or rule out diabetes and contribute to a comprehensive evaluation of her metabolic health.

While other tests like the oral glucose tolerance test and A1C test are useful in certain situations—such as further assessing glucose tolerance or giving an overview of average blood sugar levels over the past few months—the fasting plasma glucose test is often chosen first for diagnosing diabetes or pre-diabetes, particularly under the circumstances presented in this case. The random plasma glucose test, while it can indicate hyperglycemia, is less specific for diagnosing diabetes than a fasting glucose test, especially without follow-up confirmatory testing.