I've been commuting daily for most of 20 years during the summer months and have only had 4 or 5 flats while commuting in that time. It really depends on the roads, your tires and how you ride. Keep your tire pressure up near the recommended inflation to prevent pinch flats from potholes, large gravel and other road induced wheel impacts. Riding on wet roads seems to make things a little more prone to cutting through your tires for some reason. Kevlar tires do help some if you're dealing with debris like broken glass. The main thing your looking for is a tire that has kevlar belts, not necessarily a kevlar beaded folding tire. If you particularly bad streets for debris I would second the recommendation for Mr. Tuffy tire liners. They may add some weight to the bike but you'll never notice it unless you also race on your commuter bike. Channing a tire is much slower than the liners will ever make you.
You may reduce your chances but it can (will) happen eventually. You should learn how to change a tube if you don't already and carry the tools necessary to do so when you commute. For most bikes this only requires a spare tube, a pump and some tire levers. Another thing to keep in mind is to find the cause of the flat before putting a new tube in. I once had a flat caused by a little piece of wire that worked its way through my tire. I changed the tube out and promptly got another flat because the wire was still in the tire.
It is also a really good idea to leave yourself a little extra time to get to work in case you have a flat tire or other mechanical problem. Murphy's Law rules on this kind of stuff. If you work in a place where they have little tolerance for being late, plan on leaving with enough time to deal with a flat - usually 10 to 15 minutes. Showing up early is looked upon favorably with most employers.