Refined sugar is high in glucose, which has a much higher glycemic index than fructose, which is found in honey. High fructose corn syrup should be avoided because it is made of over 50% glucose despite the name.
Here is a link to the glycemic index of various foods (a glycemic index 55 or less and a glycemic load of 10 or less is usually considered low): http://www.mendosa.com/gilists.htm
Even though it is much lower than sugar, honey is still boarderline in terms of glycemic index and load so should be consumed in moderation. The best sweeteners for diabetics tend to be agave nectar (very low glycemic index ~10-12) and stevia.