I happened to attend a very much food-based party yesterday, and I've been on insulin for a year. I ate lots of wonderful food and my sugars went a little more up and down than I would have liked at home, but that's fine. It's not like I attend parties every week, so no harm done, and by the time I was back home everything was back to normal.
It's easier to keep in range now that I use a freestyle libre. It's a patch you wear on your arm that you can scan with your smartphone to check your blood-sugar. It's not as accurate as a fingerprick, but you can easily use it way more often and thus see if your bs is going up or down.
What I understand from your question is that you want to know what it's like for your son to live with diabetes. Everyones diabetes is different. We all need different amounts of insulin, some of us use a pump, some of us use a twice daily insulin which means you need to have a very regular life, and some of us (like your son) use a basal insulin plus short-acting insulin for meals and to correct high bs. Some of us test our blood only 3 times a day, others have a continuous glucose monitor with alarms when going to high or too low.
So no-one can tell you what it's like to live with diabetes for your son.
I'm happy to give you an account of ME living with my diabetes for a day, though, including that party.
Just remember, your son undoubtedly does things differently. There IS NO ONE WAY to manage diabetes!
9:30 : Woke up. tested blood. BG (blood-glucose) 6,8. I know that with me my BG rises when getting up, so took 7 units before getting out of bed. Made coffee, fed the chickens, dogs, cats, guinea-pigs, rabbits, pigeons and the pig. Drank coffee.
10:30 : Scanned BG. 5,6. Fine, but remember to check again in an hour or so, even though I know from experience my BG would remain stable for a couple of hours. After all, I'm driving. Got in the car with mug of coffee. Took the 'nice' route, leading me through the beautiful wintery countryside of Friesland and Groningen (Netherlands). Got hopelessly lost around the wonderful small historic city of Dokkum. Had to stop to ask directions, good opportunity to check again.
11:30 : Scanned. BG 5,9. All clear to go. Drove another hour.
12:30 : Arrived at party (aunts' 90th birthday). Scanned. BG 5,3. Nice, I can eat some of the coated nuts whithout bothering with insulin. (I probably would have skipped the nuts had my BG been higher). Greeted family members and spoke with different people I hadn't seen in a while.
13:00 : Soup. Not a clue about the carbs. Asked waiter. Went to the kitchen to check the package of soup powder. Still not a clue, how would I know how much powder was in a cup of soup. Promised the rather ashamed cook I wouldn't tell they made their soup from powder

.
Scanned. BG 5,9. Opted for a rather conservative 2 units. Soup tasted pretty good for powdered stuff!
Watched projected photographs with a story about the 90 years of the birthday-girls' life.
13:30 : Scanned. BG 8,5 and rising. Must have been a lot of carbs in the soup powder. Took 5 more units, knowing more food would be coming. A small starter with fish, salad and a little sauce was served. Figured there would only be carbs in the sauce, if any, so no insulin.
13:45 : Scanned. 5,3 and dropping fast. Checked blood. 5,5. Oops, the 8,5 must have been a glitch in the sensor in my arm. Possibly because I went outside with the kids in only a t-shirt while it was freezing. The good thing about it was that I got to drink half a glass of orange-juice, which I normally wouldn't. Watched a funny song by my aunts grandchildren and a video-message from someone in New Zealand. Nice!
14:05 : 6,8. Well out of the danger-zone.
14:30 : 7,8. Clearly overdid it with the orange-juice and more food is coming. The easiest way would have been to skip the bread and potatoes, and eat fish, gamba's, meat and salads, of which there was more than enough. Had I been at home I would have just waited with eating until my BG started coming down. Mind you, 7,8 is perfectly fine, but I didn't know if it was rising or dropping, and with all the food and insulin in the last couple of hours deciding on doses became more and more complicated. But this was a party and the food looked great, so I decided to go for it. So I took bread and baked potatoes, and a lot of the other stuff, took 8 units of insulin (2 because I figured I was still rising, 6 for the food).
15:00 : Back to 7,0, so had a second helping.
15:30 : 5,7. Decided to wait and see.
15:45 : 6,6 and icecream. Problem with icecream and orange-juice and stuff like that is that it makes my bg go up quick and the insulin wil get it down quick as well. Which leaves you with 'leftover' insulin in your system. If I would eat the icecream and inject for it, I would have to pull over on my way back to check a lot more often than when I would skip the icecream. Took icecream and 5 units.
16:15 : 6,7
16:30 : 7:3 and started my way back home. Took some leftover bread with me to counter the anticipated dropping after the icecream.
16:45 : 5,5 and dropping. Good, there is the drop and I caught it well in time. Munched away on the bread while driving.
17:00 : 5,7. Good.
17:30 : Got home, didn't bother testing as I wasn't driving. Walked the dogs, fed the pig.
18:00 : 6,3. Patted myself on the back for doing so well with al the different foods. Took 7 units for 2 beers. Drank the beer.
20:00 : 5,9. Made a thin slice of bread with a lot of grated celeriac, mayonaise and salt and pepper. Took only 2 units, as I knew there was still insulin in my system from 2 hours ago.
00:30 : 5,8. Bed. Took a couple of cashew nuts to stay safe overnight.
Reading this, it sounds as if I'm only busy with my blood sugars during a day like this, but I'm not. All the checking, deciding and injecting only take up a small part of my mind. I just keep talking, listening or doing whatever else it is that I'm doing and at the same time do the diabetes related thinking.
The things I'll remember from this day is playing with the kids at the lake directly next to the restaurant, the conversations I had with various family members and the video-message from my niece. The handling my diabetes that day only gives me a feeling of pride because I pretty much nailed it. I hope it will be the same for your son and that he'll just gets on with life, the diabetes being something in the back of his head.
And remember, an ordinary day involves way less testing and thinking. Those days are more like my evening, between 17:00 and 00:30.
I hope this story helps you understanding diabetes a little better.