You need to eat low GI foods before your workout in order to give yourself more stable blood glucose levels. I suggest a bowl of oatmeal, with skimmed milk- low calorie, great source of carbs, with protein.
If this is a serious problem. get your blood pressure checked out at your gym.
Another thought- do you do lower body and upper body exercises in the same workout - this causes dizziness for some people, through incresed blood pressure - the blood having to travel from your upper body to your lower body and vice-versa.
A small percentage of people actualy suffer from a syndrome in which exercise causes faintness and dizziness (forgotten the name, but is named after the discoverer), unless they take buffering agents e.g sodium bicarb or tribasic sodium phosphate. I would suggest the latter, as 2g would be sufficient (0.2g/kg of sodium bicarb/kg needed for the same effect- causes nausea in many people) - you could try the bicarb, as it is easy to get and cheap - give it a go and see if it works.
You can skip this if you like but here is the science, with info regarding supplementing with a phosphate or pyruvate for this purpose (preventing low blood sugar/utiliing glucose and glycogen):
When cells need energy, glucose enters the cell via carrier mediated diffusion (too big to diffuse across membrane on its own). To “lock” it in the cell, a phosphate from ATP attaches to the 6thcarbon. We show this by G-6-P and call it phosphorylation. G-6-P doesn’t fit on carrier, so it stays in cell. Glucose continues to enter the cell due to the concentration gradient (b/c G-6-P is a little different than glucose) G-6-Pcan be used in 2 ways
1. In the liver
2.In the muscle cells
How? The Phosphate from the 6thcarbon moves over to the 1stcarbon, making it G-1-P. Chains of G-1-P are made and the polymer of glucose created is called Glycogen.The term used for the construction of this polymer is Glycogenesis.
Usage: We reverse the storage process from chains of G-1-P back into G-6-P. This term is Glycogenolysis. Then, to burn glucose as energy, we must first add an extra phosphate to G-6-P (gotten from ATP), so there is a Phosphate on each end. It then is able to split into G-3-P and G-3-P (2 equal 3 carbon compounds named Pyruvates).This process of making pyruvate is called Glycolysis. It is basically sugar splitting. It occurs in the cytoplasm of all cells, is anaerobic and delivers a net gain of 2 ATP per glucose.
Both phosphates and pyruvate can offset an influx of lactic acid (by buffering H+ ions), at which point the muscles are using great amounts of glucose
Acetyl Co A, also slows step in the conversion of lipids back into keto acids.
If the problem still occurs, go see your GP as Type I Diabetes causes the over-metabolism of fat, keto acids building up and the person may enter a state of ketoacidosis. In cases of severe diabetes, this can lead to a ketoacidotic coma. - not saying that this will happen to you, but there could be a chance that you are borderline hypoglycemic.
Final recommendation: slug a sports drink, such as Gatoraide during your workout (assuming that the extra calories don't bother you)
Good luck Miss Dizzy Punk
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