She smiled tightly and said, “I feel a calling to educate you about my son’s condition.”

I didn’t even recoil.

“Lady,” I said emphatically, “I don’t give a damn. I’ll deal with my T1D however I see fit, and you may deal with your prince’s tantrums however you feel fit. You can’t control a tantrum, therefore I’m not putting my health at risk. The next time, reserve the whole row. Better still, take a private flight.”

It was worth the hush that ensued.

The last two hours went by without any problems. The child never noticed anyone eating and never looked up from his game. How about the parents? They didn’t speak to me again.

I learnt that speaking up for your health is not impolite that day on the plane. It’s essential.

Refusing to let someone minimise your needs is the most considerate thing you can do for yourself. Although my condition is invisible, it is real, and I am fully entitled to treat it as I see fit.

No one’s health is more important than another’s comfort. Whether you’re on firm ground or at 30,000 feet, that’s a lesson worth keeping in mind.