Final answer:
The target blood pressure for someone with hypertension, as per the American College of Cardiology and American Heart Association guidelines, should be 130/80 mm Hg or lower.
Step-by-step explanation:
The nurse should inform the client that, according to new guidelines provided by the American College of Cardiology and American Heart Association, the target blood pressure for someone with hypertension is 130/80 mm Hg or lower. Blood pressure above this threshold increases the risk for heart-related complications, including heart attack, stroke, aneurysms, peripheral arterial disease, chronic kidney disease, or heart failure. It's crucial for managing both hypertension and diabetes mellitus that the client understands the importance of maintaining their blood pressure within the recommended range.