This used to be my staple medication diet for work actually. I'd take about 30mg diaz in the morning alonside a can of Relentless(equiv to 2 cans of red bull) and about 20mg at lunchtime with another can, and then a cup of coffee on my last tea break with 10mg diaz.
It is kind of like a poor mans speedball, they will cancel each other out in a lot of ways, but mixing the two together in my case definitely decreased my anxiety tons and increased my productivity and energy levels tons too so they worked really well together, but they drove my tolerance up really fast so I wouldn't really recommend it from a HR point of view.
Caffeine is known to increase anxiety, which is why more of the benzo it normally needed if taking caffeine or any other stim with it.
You should probably talk to your doctor about mixing the two for some more advice or you could end up running out of your script too fast because the energy drinks have made you take too many benzos whilst on them.