For starters, Glycerin is NOT a sugar.

Also known as glycerol, glycerin is a byproduct created when manufacturing soap. It is often used in water-based sexual lubricant products, commercial baked goods, candies and clear soaps. The simple compound retains moisture, although when applied topically, glycerin could potentially cause dryness.

There is also some evidence that women who are susceptible to yeast infections may want to avoid lubricants with glycerin, since glycerin could potentially facilitate the growth of harmful bacteria. While glycerin cannot directly cause a yeast infection, glycerin can increase the growth of yeast which in turn may increase your susceptibility to a yeast infection.