Zero sugar on the run is hard... Hard boiled eggs and veggies, maybe? You can cook the eggs the day before, or even cook a big batch of eggs in the weekend. You could also cook yourself an omelette the night before and reheat it at work in the morning.

If you don't mind a bit of natural sugar, you could also have some no sugar added Greek yogourt with fruits like berries, banana or apple. For minimal prep I like to use frozen berries. Add some in a container, nuke them to defrost, then add the yogourt and mix. The juices flavor the yogourt so its like making your own flavor mix with real fruit and no sugar.

Nuts. I get a container of nuts at the grocery and keep them in my bag to snack on-they are full of protein, but they also have fat

Sometimes I make a lot of things in batches, so that I can have a quick thing when I need it. Meals I can make extra to go into homemade t.v. dinners. Hot cereals, like quinoa. Brown rice. A quick layered fruit salad (unless you have trouble with the fructose too). Most of the time though, I try to watch the sugar and gi on them. And I keep a variety of sulfur-free dried fruits and nuts on hand for trail mixes.

If you have a microwave at work or even at home (as long as you have a short commute), you can poach a couple of eggs. I just learned this method and it works pretty well. You put some water in a microwaveable bowl, crack in a couple eggs, pierce the yolks with a knife, cover with plastic wrap (I didn't do this and had a mess), and then nuke for 1:30-2 mins. Drain off the water and you're good to go. I cooked mine in a glass container that had a lid and after I cooked them at home, I packed for work and they were perfectly warm when I got to my desk.

Similar to what Lmola said, I like to get a microwavable glass blow with a tight fitting lid and crack one whole and one egg white (save the yolk for something later) chop some mushrooms and green peppers, dice a bit of deli turkey or chicken. Top with green onions and some fresh ground pepper. Take it to work, shake it up, nuke it (with the lid off) for a couple minutes (depending on your nuker) until its poofy and cooked. Let it cool it will be super hot! Then enjoy! There will be a little bit of sugar but the good kind :)