As permeakra mentions, glucose can be purchased pretty easily. It might be labeled as "dextrose".
Another commonly available is maltose (or malt sugar).
Sucrose (or table sugar) is not a reducing sugar, but one of its constituents (glucose) is. Glucose can be made from sucrose by heating with a little bit of acid to make invert sugar syrup. Invert sugar is approximately a 1:1 ratio of glucose to fructose, and only the glucose in this mixture is reducing. An example procedure can be found here:http://chemistry.stackexchange.com/questions/555/how-does-adding-lemon-juice-to-sugar-make-better-caramel/556#556How does adding lemon juice to sugar make better caramel?. Honey is a naturally occurring invert sugar.