if you google the "DASH diet" - it's a great diet to follow for high blood pressure and I'd simply keep my whole grain choices on that diet to 2-3 daily within my meals - not as snacks.

another diet you can google is the Mediterranean diet, which may help with both the pre-diabetes and high BP.  Try to steer clear of high sodium, processed foods - you can "google" - high sodium foods and you'll get quite an extensive list.  You should find out from your doctor if you are "salt sensitive" and he can tell you specifically how much sodium you can have in a given 24hr period.  Leaning to small portions of lean protein/healthy fat serving/whole grain small portion of carbohydrate (actual grain, fruit or veggie) at each meal is a good starting point.  Make snacks small serving of protein foods (fat free dairy can work) with a small serving of a fruit or veggie.  If you are overweight - consider losing some lbs. which can help both conditions.  That also means starting a walking or exercise program.