Assuming that you are not taking any medications that slow down your heart rate, this indicates an abnormal response to standing. If your blood pressure falls, normally your heart tries to pump out more blood by beating faster.
There may be a problem with your autonomic nervous system. Disorders of the autonomic nervous system can cause postural hypotension in people with diabetes, certain genetic conditions, and some rare diseases.
Call your doctor's office for advice and to arrange an appointment.
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