There similar reports a couple of months ago, but this one has more specifics:
Blood alcohol levels peaked at around the same time — 30 minutes after having the drink — regardless of which mixer was used. The difference, however, was that alcohol levels surged higher with the low-calorie mixer: to 0.05 percent, on average, versus 0.03 percent with the sugar-sweetened mixer.
In some jurisdictions, this would mean the difference between driving legally and driving drunk, according to the study authors, led by Dr. Christopher K. Rayner of Royal Adelaide Hospital.
The difference in peak blood alcohol levels was “striking,” the researchers write, and it shows that a drink’s alcohol content isn’t the only factor people should consider.