As of 2015, some research suggests that agave nectar has a lower glycemic load than refined cane sugar, according to WebMD. Agave nectar is slightly sweeter than granulated sugar, but contains roughly 50 percent more calories per tablespoon.
Agave nectar or syrup is a sweetener made by refining the sap of the agave plant. The agave plant has served as a medicinal herb in Mexican traditional practices for centuries, according to Authority Nutrition. Unrefined agave sap contains fructans, which some research links to positive effects on metabolism and insulin production. However, the refining process that turns agave sap into syrup likely destroys these compounds, turning them into fructose.
Agave nectar has a low glycemic index number compared to other sweeteners such as corn syrup and cane sugar, notes All About Agave. The glycemic index measures the impact of a given food on blood sugar and insulin levels.
Fructose does not travel directly into the bloodstream upon consumption and therefore does not affect short-term blood sugar levels as much as glucose. Because the sugars in agave nectar derive mainly from fructose, this food does not cause blood sugar to spike after eating. Only the liver metabolizes fructose, whereas any cell in the body may metabolize glucose. Excessive intake of fructose may put undue stress on the liver, according to Authority Nutrition.