You and your husband should have a conference with a dietitian. I like those lower carb, lower sugar nut bars. I know Kroger's and Marsh have their own brand. I think they're called sweet and salty, or something like that.
Some people are very sensitive to salt, so if he's not sweating alot, he should try to eat less salt.
There's always raw veggies, fruit, nut butters and whole grain crackers. You can find drinks that are higher protein, lower carbs that are good for diabetics.
Unsalted or low salted mixed nuts are a favorite snack of our's. Yes, they are higher in fat, but no carbs and good protein.
You can add a little bit of dried fruit to the nuts to give it a little sweetness.

I agree with Catherinet, talk to his doctor or dietitian. There are many variations of diabetes, and there isn't a cover-all answer for all diabetics.

I am hypo-glycemic, and many of my snacks are the same as a diabetics even though they are the opposite medical problem. I like Trader Joe's version of a fruit rollup, they are really good and fit in a pocket or purse easily. They provide quick fructose. Also crackers or mixed nuts are a good option, I like to keep a trail mix with nuts, M&Ms and raisins handy for a quick snack too (Costco has the best for cheaps!).

Good luck, it isn't an easy disease to live with, but you get the hang of it!