Hello, If these readings are in mg/dl then these are dangerously low and no wonder you are feeling dizzy and light headed. There can be several reasons: most importantly, are you on any medication to lower glucose levels? If yes, these need to be reviewed by your Specialist If not, then you need to see an Endocrinologist to ascertain why your sugar levels drop so rapidly. The important thing to exclude is whether insulin secretion or levels are rising rapidly due to a pancreatic problem for which the sugar or glucose level is dropping. Best Wishes.