I use a great treat called beet-e-bites because they are low carb, low sugar. I have one I/R horse and one who is not, and I give them both these treats. They LOVE them so I son't tell them that they are very healthy!!!!
Molasses is the scariest thing I can think of to give a horse, carrots and apples are high ins sugar. Think about all the diabetes in people. Our horses are also becoming Insulin Resistant because of diet so I would never give a treat with all that "junk" in it