Hi Linda,
I am not sure if your husband is T1 or T2, but (as others have said) food substitution is easier than carb counting. If this is not always possible, then severely restricting the quantity of something also works quite well. I travel for work and often have little choice in terms of menus, with rice often arriving on the plate. So rather than eating all if it, I stick to a minimal amount or none. Also, having nice things like chocolate is ok, if you stick to 80% cocoa or higher, I go for 90%+ if possible. My blood sugar levels (mg/dl) when diagnosed three months ago actually started going consistently between 70-90 (3.9-5.2m/mol) , they advised which me was often too low, so they ended up taking me off one set of pills. Now, with a sensible diet it is usually 93-140 (5.1-7.8m/mol), the latter if I have had something higher in carbs. Usually it is around 100-120. You can also try introducing something new and testing before having it and two hours later. I have done this with a variety of foods and also wine. I don't advocate alcohol as a treatment, but I found red wine significantly reduces my blood sugar level. Which is good, but also needs to be watched.
Another key tip I would say is balancing the portions on a plate, e.g. 1/2 vegetables, 1/4 protein and 1/4 starch. Not forgetting some fruits and dairy as well. Also, choose the foods within that wisely, ensuring lots of fibre etc. I found this approach has filled me up, gives me enough energy and I have also continued to lose some weight without even calorie counting. It is also a very easy way to carb count indirectly.
However, always get proper medical advice.... We are all different.