I've worn thick diapers 24/7 on and off for over a year. You'll feel like your diaper bulge and crinkling noises are impossible not to notice, but the fact is that basically everybody will be completely unaware. As Slomo mentioned, be sure you wear shirts that are long enough to keep from coming untucked, and be discreet about your clothing choices, but as long as you don't go out of your way to make it obvious, none of your coworkers are going to have the slightest idea what you're wearing.
Look at it this way: How many adults have you noticed wearing diapers? Several percent of the population is incontinent and wears anything from thin pullups to thick cloth diapers, and I'd be willing to bet you've never noticed anybody wearing unless it was pretty obvious or you had some other reason to suspect. Your coworkers, who aren't thinking about diapers in the first place, won't have a clue.
