One individual wouldn't eat a whole tin in a meal they probably wouldn't eat 100g and its the sugar content that is more important than the carbs. You need carbs for energy you don't need sugars.
Nutrition infomation taken from 2 different brands of 300gm cans of Green Lentils in water
Per 100gms
Carbs 15.7g of which Sugar 0.3g
Carbs 11.6g of which Sugar 0.2g
Carbs are low and sugars neglible.