I was a paramedic for 15 years, I would routinely use peanut butter right out of the tub on a spoon or peanut butter on white bread sandwiches to treat hypoglycemia in patients who were alert and able to follow commands. It works great, it's probably the best food for the job; I preferred it over OJ because it has a little more sticking power than just straight sugar as in OJ.
This must unfortunately be said based on having treated patients where this happened: NEVER PUT FOOD OR LIQUIDS INTO THE MOUTH OF SOMEONE WHO ISN'T ALERT AND ABLE TO FOLLOW COMMANDS.