I'm sorry there was a typo in my post above. I meant to say "what causes lows are too much insulin or too little food (carbs)." The two need to be closely related, so that he isn't taking too much insulin for how much carbs he is consuming. (That's why the I:C ratio is the best way to determine dose.) Btw, blackheart, oj is a great treatment for low blood sugars but peanut butter will do very little, though it's a good snack. You need a fast acting high carb item, such as OJ or just get glucose tabs from the drugstore as they are the fastest acting and easy to keep around the house.
I am 21 years old and have had diabetes my whole life but i agree with zoelula somewhat cause age matters with diabetes so if he is under the age of 17 its most likely what he is eating not the insulin cause his body is burning more sugar then what he is putting in so he needs to eat snacks and check his sugar often its rare but also his body may be rejecting the type of insulin he is useing it happen to me but like i said its rare and if the doctor did not tell you this never let soneone with a low blood sugar fall asleep they could go into a diabetic coma. i went into one b4 not good
P.S. orange juice and peaunt butter works best on low blood sugars hope that helps
I know how scary severe low blood sugars can be. They are not always avoidable, unfortunately but there are definitely things you can do to minimize them. Many lows are caused by too much insulin or too little or both. You said something about a "sliding scale" for breakfast. I assume this determines the bolus dose by what the blood glucose is before the meal. Just to let you know this is a somewhat outdated method. More exact is to match insulin to food by a I:C, an insulin: carb ratio. You need to determine the correct ratio for your son which might differ for each meal. Then you count the exact number of carbs he will be eating and figure it out from there. 1:15 is a good starting place and then you need to experiment and see his correct ratio which might be more or less. 1:15 would mean one unit of insulin to every 15 carbs. Get the book, Using Insulin by John Walsh or Think Like a Pancreas (I can't remember the author).
Another way to avoid lows is to test, test, test. He didn't get to 22 without passing through the higher numbers of 70, 60, 50. You don't say how old your son is but if he is old enough to recognize and describe feelings of hypoglycemia he needs to treat it when it is below 60 with some glucose tablets.
It is also important to avoid "stacking". Adding more insulin when there is still a dose onboard and active. You need to learn how long your insulin lasts and when it peaks.
Good luck.