As a Type II diabetic, I ordered special meals for BA's LHR-PHL and BOS-LHR recently.
Meals were served ahead of the main cabin service, and I was also asked if I would like the snack on the outward earlier than the planned time to suit my sugar levels.
In general the meals were 'nicer' than those served to my travelling companion - but the 'ginger chicken with mashed potato' on the return was frankly HORRIBLE - served to us both. The diabetic afternoon 'snack' was both healthier and fresher than that offered to my companion, and I think that I will continue ordering special meals for future long-haul sectors. The 'nibbles' bag offered on LHR-BSL was an insult to anyone who takes their health seriously and watches what they put in their mouth.