After a heavier than normal meal, rising up and walking feel dizziness, as though blood is concentrated in the stomach alone. Feel a higher heart beat and also difficulty in walking on. The heavier meal is a trigger. And sometimes getting of a car after driving have felt the same lightheaded ness and dizziness and finding hard to walk on or climb stairs. Feel loss of strength and not normal at all. I am 66 years old, diabetic with hb1ac at 7.5 all other parameters regarding blood, lft, kft,lipids and tsh etc absolutely normal. What other tests or investigations done to correctly diagnose the problem.