Can consuming a lot of sugar before a blood pressure test cause hypertension?

Not likely: Sugar consumption has little effect on blood pressure, even in a diabetic, unless that individual develops low blood volume and dehydration from extremely high blood sugars, in excess of 600-700, .

No: There is no known correlation between high glucose levels and high blood pressure.

Not hypertension...: but possibility transient elevation in blood pressure which is not same thing as hypertension. Acute hyperglycemia (very rapid rise in blood glucose) in newly diagnosed type 2 diabetic patients can cause significant hemodynamic changes including elevated systolic and diastolic blood pressure by 10 mm. This would be unlikely in a non-diabetic patient.