My doctor recently changed my medication from 160mg once a day to 320 mg once a day. He said it would not make much of a difference in my readings. I average around 115/75-----120/80.. I have noticed on a few times that my numbers have been very low---90/56.. Is this something I should be concerned about? Should I let my doctor know? These low numbers are usually an hour or so after aerobic exercise.. I am just wondering if the doubling of the dose of Diovan has anything to do with this?
One of my co-workers said his brother had low blood pressure like this and he died...

Exercise will temporarily lower your bp, but then it comes back up again. What I don't understand is why if your readings average around 115/75 to 120/80 you were told to INCREASE your dosage! Unless you have some medical condition that requires much lower blood pressure, 115/75 to 120/80 is considered normal with no further reduction needed. On top of that, your doctor told you increasing your dosage wouldn't lower your bp very much anyway - so why is he increasing it?

You need to seriously quiz your doctor on his rationale for your increased dosage. If he can't give you a good answer, insist you go back to 160 mg. There is no reason to take more medication than you need to keep your bp in the "normal" range.

Actually what happend was I had a physical about a month ago and when he checked it in the office it was 130/80.. I have "white coat" and my blood pressure is always higher at the doctor's office. When I got home that day I checked it and it was 120/82. I should have questioned him when he did say the increase in the dosage would not make a big difference. Maybe he meant the increase in the dosage would not lower it drastically. Not sure.. I sometimes wonder if I truly even have hypertension or just white coat. My readings at home were in the normal and high normal range before he put me on medication.....They were always high at the office only.....

Obviously your last couple of sentences are a pretty strong argument for getting off the meds and hitting the lifestyle remedies hard for a while and see what happens. At least share that opinion with your MD.