Tried it a number of years ago & found out that: (1) the solution often got into the soil & provided food for fungal spors & some times resulting in damping off. (2) "Osmotic Pressure" the water from the plant flowed into the suggar water causing dehydration & death of the cutting.
For these reasons & others I stoped the practice & depend on IBA (rooting hormone) to speed up the rooting process & increase my % rooted.

I agree with George. Sugar feeds microbes and contributes a bit to unfavorable osmotic shock.

The solution is hypertonic, therefore, the plant is hypotonic and the water will go into the plant. In other words, there's more water on the outside of the plant so osmosis will happen and the water will be drawn into the plant.

The sugar is energy for the plant. It's plant food.

There's good microbes and bad microbes and if your cutting is in clean conditions, it should have a natural resistance to the parasitic microbes and the sugar won't be a problem.

ms_minnamouse, you should go over to Wikipedia and correct Hypertonicity: A cell is surrounded by an environment with a higher concentration of solutes than within the cell itself, resulting in water leaving the cell through osmosis. wink, wink.

The Wikipedia editors even state This article is in need of attention from an expert on the subject. And being an expert, ah, wink, wink.

There is no doubt that sugar is the energy source for plants and it's also the energy source for fungi and bacteria. You don't want to grow fungi with your cuttings. Normally, don't use sugar unless you know how to control fungi and bacteria. You may consider using preservative with very diluted sugar solution. Many our drink and food are mix up with food preservatives to to extend shelf life & improve food safety.

Osmosis problem happens not only with sugar but also with fertilizer when mix too much of them with water. The question is how much is too much?