Hi David,
Thank you for your question to the forum.
It is very important that insulin is given as prescribed by your diabetes team. I can understand though why you didn't give the insulin if your son's BGL was low.
As a general rule, if the BGL is low, treat the hypo as recommended, re-test the BGL and then give the usual dose of insulin that is due.
I recommend you call your doctor or diabetes educator for further assistance.
Kind Regards,