We never tried, but I don't think you will see any difference from regular sugar (sucrose).
It's debatable whether regular sugar survives saponification, without breaking down.
Normally sucrose hydrolysis is performed enzymatically or in acid and yields 1 fructose and 1 glucose (dextrose) per each sucrose.
In the basic conditions of soaps, sucrose hydrolysis is slower and more complex, but you can expect a certain degree of decomposition anyway, if only due to the temperatures.
I would say go ahead and use the same amount as you will use regular sugar, the effect will be probably the same, including acceleration/heating of the soap during the first hours after tracing.
Same thing about the lather boosting effect!
Though I wouldn't spend my money on it... since glucose is derived from sugar. Unless I had it free. Or I will do some fancy glazes, and syrups, and confectionery with it :-D.
Dextrose does not crystallize from a syrup over time, unlike sugar does!
Cheers,
Lorenzo