I wonder what his c-peptide test result would be? He may even be a Late onset T1 and not T2, although I would hope his consultant has carried out the test and not just guessed T2.
Yes, this had me wondering as well.
At the moment I am assuming that he was correctly diagnosed as T2 but the only available treatment option which also allowed him to maintain his peak performance on a mainly carbohydrate diet was insulin.
It would be good to know if he was able to modify his approach once he quit the intense training regime.
However I do know people (including one of my cycling group) who decided they would rather maintain their current eating style (which may or may not have contributed to their diabetes) with insulin than try a major lifestyle change.
IMHO a valid lifestyle choice which I would not make.
One illustration of the downside of this approach is the inherent hypo risk. My cycling buddy is also a dingy sailor who had to give up single handing in case of a hypo when out on his own. There are also implications for driving.
I am also needle phobic, which is an added incentive to stay off insulin.