Although it turned out to be a different medication in JY's case, I have known two people that inadvertently gave themselves too much insulin.
One misread a decimal point and gave himself 10x the correct dosage, requiring immediate emergency care as soon as he realized what he did and started to have symptoms shortly thereafter.
Another tested his blood sugar prior to a meal. When looking up the correct dosage on a table prepared by his doctor, he looked at the wrong line and gave himself a slightly higher dose than needed. Although it wasn't as life-threatening as the above instance, he still went the emergency room. Fortunately, he only needed to drink juice and eat a candy bar while they monitored his sugar to make sure it didn't drop too low too fast.
That said, I agree that the dosage pens for insulin and other medicines are made to be as easy to use as possible and minimize the likelihood of giving the wrong dose.
With people so litigious today, every possibly-known side-effect gets listed - no matter how improbable - so that the drug companies can cover their asses and minimize their liability in a lawsuit over unspecified side-effects.
Here, there seem to be many commercials on over-the-air TV between 6 & 7 PM for medications, drugs, and stuff that sounds like borderline woo. In many cases, the side-effects being mentioned near the end of each commercial are so numerous and severe it's enough to make one think that having the disease is less of a health risk than taking these newer drugs.
Most people needing ambulance transport are in such a state of hurt that any type of selfies, live-streaming, or social media posting is furthest from their minds. Anyone who seems well enough to post a selfie and "converse" lucidly to their followers comes across as not needing an ambulance unless one was called for them as a precautionary measure or to minimize someone else's liability.
Without knowing what's on the bracelet, it could be for diabetes or it could be for drug/food allergies or any other important medical information first responders would need to know if the person wearing it is too incapacitated to communicate those details.
Please don't give him any grooming ideas.