Could whey protein cause hypoglycemia?

No: Eating protein does not cause hypoglycemia (low blood sugar). If one is getting what he thinks are hypoglycemia symptoms, a primary care doctor can check it out to see if there is actual low blood sugar, or just symptoms similar to that of low blood sugar. On the other hand, what is being mixed with the whey protein? A smoothie with a lot of sugar may lead to hypoglycemia symptoms some time later.