Hi,
How are you? Aside from fluctuation blood sugar, as mentioned by Ginao4, presyncope may also be due to changes in your blood pressure, eye or ear issues, vertigo, anemia and other neurological conditions that needs to be evaluated by your doctor. Have this checked by your attending for proper evaluation. Your complete medical history, physical examiantion and diagnostic tests including blood tests and neurological examination will help determine the underlying cause. Take care and do keep us posted.
Could be nothing but I would get checked out. For starters, see if your doctor will do some lab work and check your blood sugar. Sugar levels that are too high or too low can cause this kind of thing. I would also ask for a referral to a neurologist to check for MS. Again, it could be nothing but it is better to get checked out to be sure.