Changing from Nova Rapid to Fiasp

I changed to Tresiba from Lantus after 15 years of using it, much more stable and less nocturnal hypos.

In regards to FIASP, I also changed to this from Novorapid around 2 years ago, made a world of difference to me. In essence it is still Novorapid, but has two additives which increase the absorption of the insulin, hence it works faster. I found the peak to be around 1.5 hours but it works much faster and stronger within the first hour compared to novorapid. So really helps with high carb foods when you don't want too much of a rise.

Dosage wise I stayed the same as novorapid, but you do have to bare in mid if he eats low carb/fatty meals, you may need to split dose more with FIASP as it works quicker so may work faster than blood glucose increases. It stays in the body around the same time overall, but the majority of it I found out of my system after 3 hours.

You do really need to bare in mind where he injects though, as injecting in legs/buttocks will be significantly slower regardless of insulin that abdomen or arms.
Overall it was a really good move for me and I would recommend it.

Some people found it stopped working after some time but I found if I keep the in use insulin open for ni longer than 2 weeks, it worked very well, obviously keeping it out of high temps etc.

Hope this helps, let me know if you need anything else.

Welcome to the forum Charlie&Reggie. I'm on a pump, but changed to Fiasp a while ago now. My experience has been generally good, but I still need to give Fiasp 20 minutes before a meal. It's reduced the high spikes I was having post meal, but as Munbeeb said, I need to do more split doses with a high fat/carb meal or I hypo (much easier on a pump I realise). With any change of insulin, it's important to monitor how quickly it works etc, as we're all individuals. Hope it works well for your son, and the school are supportive.