Hi Iain,
What a remarkable son you have, he has done extremely well and as parents your probably the ones needing the extra support and ((hugs)) I'm mum to Andrew who is 11yrs old T1 and almost 4yrs since diagnosis, not quite at those teenage years yet, but his attitude is certainly half way there!! plus puberty is beginning to kick in, I also half a 13yr old non diabetic son.
Theres plenty of help here and a few more parents with teenagers, i'm sure we'll be able to help, plus quite a few very sporty older T1's, who are into the gym and cross country.
Take care and well done Ben,
Suzi x