Leg numbness in a newly onset juvenile diabetic pre teem

My son is 11 years old and was diagnosed with Type 1 diabetes in September.  He has recently begun having episodes of complete numbness in his leg and foot, this comes on quickly and he's fallen and can't move his leg for hours.  We've ended up in the ER twice only to be told this is common in a diabetic?  Are there any other tests that should be run to confirm it is not something else?  

[Gabrielaaa]

Hi, I'm 16 years of age and I've had diabetese since I was just 3 years old (They can't tell if it was from birth but, hey ho)
I get common pains in my knee's either when I stand up for too long or when I sit down for too long.
When I feel make it stay away is if I have my knee's bent and they hurt, I straighten it, and vice versa.
I know it's not the same, mine may be growing pains, and so may be your sons but just different symptoms of it.
I hope I could help in some way :)