you did not localize about pricking sensation?in which part of the body?
its most likely to be case of diabetic neuropathy
in which the nerves get affected due to high blood sugar levels....
you can get him checked for vit b12 in the lab and you can get him evaluated for d.neuropathy.
you can start with tablets cantaining methylcobolamin,benfotiamine
by consulting your diabetologist
dr vikrant tari
diabetologist and insulin pump