Suggest Treatment For Burning Sensation In Nerves With Leg Pain

My mother is suffering from hyperglycemia(140/200) and she takes 20 units and 15 units of insulin everyday.she experiences a hell lot of pain in her legs and back, a kind of burning sensation in the nerves as well.her medication includes 4 pregalin 75 capsules a day.she weighs only 30 kg and has negligible muscles left to be seen on the body.4 months back she was hospitalised for DKA(went into coma).Nothing seems to be working to relieve her pain.she cant even get up coz of pain.Please help.atleast suggest some medication for the pain shes going thru.