I have noticed that my blood pressure is different in each arm though, and I was wondering if that is normal. "i have been on blood pressure medication (diovan hct tab 320/25mg) for over a year now to help me with my migraines, and it also helps my blood p

A . A difference in blood pressure from one arm to the other can be due to arterial disease, with hardening of the arteries leading to a narrowing of the blood vessel that supplies one of the arms; specifically the one with the lower blood pressure reading. This is generally seen in older patients with established vascular disease and is usually not dangerous. The blood pressure in the higher reading arm should be used when making decisions regarding medications for high blood pressure. Differential blood pressure readings, especially when lower in the left arm, can also be due to disease in the aorta, which can affect younger patients and can be very serious. From what you have described i would advise you to have this evaluated further.
Can be normal. Theoretically, the pressure should be the same in both arms since they are both connected to to one heart. However, blood pressure changes slightly from moment to moment; it is generally accepted that a difference of 5-10 mm between arms is not significant. Rarely, arteriosclerosis of an arm artery or a narrowing of the aorta (coarctation) causes a difference which might merit special testing.
As . As has already been mentioned, this difference in blood pressures very likely indicates atherosclerosis, with narrowing of the artery that supplies your left arm. This process can also affect other arteries, including those that go to brain and your legs. You might also have narrowing of the renal arteries, which supply your kidneys. This can, in turn, lead to high blood pressure, which you say is also present. This makes it even more important that you be evaluated for hardening of the arteries: fixing a narrowed renal (kidney) artery might correct your blood pressure an eliminate the need for blood pressure medications. In general, the evaluation will include a measurement of your cholesterol and other blood components, measurement of blood pressures in your feet, and possibly ultrasound or other imaging studies to look at the vessels directly. You may be started on a low-grade blood thinner like Aspirin to reduce the chances of blood clots in the arteries.