If you have diabetes, this can be a symptom of hypoglycemia. Here's some information on that from MedHelp.org and the Sugar Sense app. You can find this in the app by clicking the menu bar in the upper left and selecting Health Guide, then navigating to the Stay Well section.
When one goes from a sitting or lying position to an upright position there is a drop in blood pressure which may cause dizziness. Normally such dizziness is very transitory because normally the body makes a quick adjustment for this "orthostatic" type of blood treasure drop that may cause dizziness. But there are many other causes of dizziness such as vasovagal problems and heart conditions.
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