Have you ever tried Xylitol? I have Xylitol made from 100% birch tree (Ultimate Sweetner). Xylitol is often used in toothpaste and healthfood store chewing gums. It has no aftertaste that I can detect (I barely tolerate taste of Splenda.) and it is considered diabetic safe with very very low glycemic value, although it does have some carb value, plus it doesn't have the punch in its sweetness than real sugar.
If coleslow with Splenda doesn't taste very good, you may want to try Xylitol. I believe there are xylitol based imitation honey on the market also (assuming you used to make your coleslow with honey instead of sugar...)
I use honey in my coleslow, sweet wine in some dishes, and I don't worry too much about small amount of sugar in condiments, etc, but when something calls for a small amount of sugar when I am cooking, I use Xylitol, or half xylitol and half sugar (I am not diabetic, but I don't do well at all with any fast acting carbs.)