First, you need to know if he feels any different when his bs is lower. If he is unaware of the drops, this is a more difficult issue to handle. I will tell you that personally, glucagon became more of a problem than a solution for me and my seizures. Next, keep in mind that the body has normal ways to combat the drops in glucose, so that 200 bs may have been a great measure of his bs after his liver had already dropped its store of glucose. The body will drop glucose from the liver when it detects the first lows, usually while we are sleeping. The recovery may wake us, but when we do a test, we get a 200 result and blow off whatever woke us and return to sleep. By now, the body has exhausted its stores of glucose, and if the insulin has not peaked or is continuing to work, we will slip into a second low, without any stores, which takes us into a seizure as the brain begins to shut down extraneous areas.
Also, keep in mind that other undiagnosed issues can cause these lows; for me, an undiagnosed liver disorder had my body fighting unrecognized infections that caused unexplained lows and resultant seizures despite a pump and CGM system.
Lastly, do not depend on glucagon, especially for a kid his age. The after-effects of glucagon are not pleasant and can result in hypergluycemia and difficulty getitng bs back in control. If he is unconscious and unable to swallow, then by all means use it, but if he isable to swallow, drinks are the way to go. I spent several years around that age using glucagon for every seizure and ended up spending the rest of the day recovering and struggling to get control again. Finally, I gave it up and resorted to paramedics when things became too difficult to handle.
Always have a neurological exam done to rule out any other causes for seizure, even when accompanied by lows.
Most diabetic people tend to go higher when excited because adrenalin acts somewhat as an insulin blocker, but I actually tend to drop lower when excited, and I always have. In my case, even though I have been diabetic for 38 years, I believe I am still somewhat honeymooning. That is, I believe my pancreas works a little bit when stimulated by either good or bad excitement. When this happens, my glucose levels can drop very quickly. And seizures usually happen when we drop low if glucose levels are the cause. In my case, it has happened at happy events such as a sister's wedding, when I thought everything was just fine. Your son may still be producing some insulin of his own at times, too, and stimulation might be just enough to give him a dose when he doesn't need it.
So my suggestion is that the next time he does this, first try to get some juice or a glucose tablet into him OR keep a glucagon kit handy so you can give him glucagon to help him recover (more about glucagon in a moment), and then even before he recovers, quickly do a finger ***** on him to see what his glucose levels are right at that moment. That's really the only way you will know for sure if he is dropping low.
Now, one more suggestion. Since he takes Lantus, you might want to ask his doctor about possibly switching his Lantus dose to the morning. Some of us who have problems with lows in our sleep do this, and the reason is that Lantus does have a peak time of action, about 4-5 hours after the injection. For some people, that peak is a stronger event than for other people. And so night lows can happen. Because the Lantus lasts for 24 hours, the way we do this is to back off one unit of the evening dose the first night, and take a 1-unit shot the next morning. A couple of days later, we reduce the evening dose by 1 more unit and add it to the morning dose the next morning, etc. until the right balance is found. Many of us do need to end up taking some Lantus at night so our sugar levels don't rise while we sleep. This is called a split dose of Lantus, and it can really help with night lows if the Lantus is the problem. It's worth discussing with his doctor.
You sound like a wonderful mom. I was 12 when I was diagnosed, and I can assure you that in time he will be better able to take care of himself. I keep not one, but TWO small 6-oz cans of apple juice on my nightstand and I always go to sleep with my glucometer on my nightstand too. So if I wake up in the night, I test to see if the reason is because my sugar is dropping low or rising too high -- both will wake me up. The juice is right there in small cans if I need it, and no real effort is required.
Now, for glucagon. This is a kit that your doctor can write a prescription for. It comes with a syringe and some liquid that, when injected, stimulates the liver to dump emergency sugars to bring a severely low person back to consciousness. I believe every home of a type 1 diabetic should have a kit in the cabinet just for instances like the seizures. When having a seizure, the child might not be able to swallow juice or a glucose tablet and might choke. If the person has any trouble swallowing at all, it is MUCH easier on everyone to simply give a glucagon injection. It works quickly and in about 15 minutes, the person is back to normal. It is suggested that the person eat a small snack to actually bring in some outside carbs after having a glucagon injection, but it can really be a lifesaver. My husband has used glucagon on me at times and it is much easier on me than trying hard to swallow juice when semi-conscious.
One last thought... I think that if you do a glucose test while he is still in the seizure mode and his glucose levels are NOT low, you need to get him to a doctor to try to find out what the cause is.