Discuss with your diabetic child ahead of time just how much they may eat. Also ask the parents of any other child with diabetes to instruct their child. Good selections are tiny, quartered sandwiches, mini-bagels spread with low fat cream cheese, cherry tomatoes, baby carrots, popcorn, pretzels, small plastic bottles of spring water, etc. Shuffle a deck of cards. Deal a card to each person, then have them move their animal the number of spaces shown on the card.
Face painting is always fun.
Face paints are available at most costume or hobby shops. Have a teenage sister or neighbor hired to help create hearts, flowers, stars, butterflies, etc. Make sure to supply a mirror so they can see what's being done. When it's time for lights out, tissues and cold cream will easily wipe off the paints so that they don't stain their sleeping bags or pillows. Flashlight limbo will get a lot of laughs.