The best way to see the carbohydrate content of a food (and therefore understand how much it is likely to raise blood glucose), is to check it online.
this is what I found about malt extract:
https://www.nutritionvalue.org/Syrups,_malt_nutritional_value.html
the carb content of 76% makes it very likely to raise blood glucose significantly
depending on portion size.
malt extract has a number of other nutrients in it that you may consider useful to you, but all those nutrients can be found elsewhere, in other foods.
Personally, I view malt extract along with sugar, honey, fruit sugar, dates, grapes, pomegranate syrup and glucose syrup - basically I avoid them since sugary foods drive my blood glucose up, unless they are in v small quantities buried in a carbohydrate free main meal.
depending on the control you have over your blood glucose, your type of diabetes. And your medication, you may make other choices.