I struggled to find anything on the Mars website (makers of Snickers) containing gluten information. However, I have read the label and the only thing related to gluten is the glucose syrup, which “sources include wheat”. But according to my Ingredient List booklet put out by the New Zealand Coeliac Society, the wheat in glucose syrup is so highly processed that it is gluten free. The safe food list on the Celiac website also says glucose syrup is gluten free and does not differentiate between wheat and non-wheat sourced. The Celiac website candy list updated January 2013, also states Snickers bars are gluten free.
So when I decide to treat myself with a chocolate bar, I am happy to eat a Snickers bar and I have not had a reaction.
Please remember though, the Snickers Bar wrapper that I am reading from for the ingredients was made in Australia and could be different from Snickers bars made elsewhere in the world. I only say this because on my post about the delicious Bounty bar and whether that is gluten free or not, a reader (John) left a comment saying that his Bounty bar had different ingredients to the one I was reading.