According to Atkins...

Glycerine: Also known as Glycerol or glycerin, this sugar alcohol is a thick liquid used by food manufacturers to improve taste, add moisture and impart sweetness. Glycerine is classed as a Carbohydrate, but does not impact on Blood sugar levels the way such carbohydrates as cane sugar do. Consequently, it can be used as a replacement for cane sugar; glycerine is 0.6 times as sweet as Cane sugar. Chemically, it is a 3-carbon molecule with three hydroxyl groups, and is one of the most common alcohols found in human metabolism. It is also found naturally in animal and plant products and is the backbone of Triglycerides (Fats) and phospholipids.