I can only say that it shouldn't, but I do eat cucumber and I have normal blood glucose - so I cannot swear to there being no correlation.
What I can assure you about is that it isn't magic. Cucumber is a low carb fruit (yes, fruit) and they are a good sensible choice to eat. Excluding high carb foods is the real key to lower blood glucose, at least for an uncomplicated type 2 it is. It might be beneficial for many people diabetic or not.