Hello elenanur,
Using an elementary flow (green leaf symbol) rather than a product flow (blue cog) will not carry all the emissions that go into producing glucose. If you are using an "emission to water" elementary flow, OpenLCA will calculate as if you take glucose out of the water, having a positive effect on the environment. Using glucose as an input in this way is similar to using co2 as an input when you grow trees - meaning you take something out of the environment and include it in the product.
If you need the production of glucose, you can find it in EcoInvent under production of starches, or try searching for it in secondary literature.
Good luck
