sign, symptom, or diagnosis, it is appropriate to assign both the V code and the code describing the reason for the non-routine test. 18
The difference is in the types of non -nutritive sweeteners used. Diet Coke has aspartame while Coke Zero has a mix of aspartame and acesulfame potassium. The beverages have different levels of sweetness and off tastes (I.e. high levels of aspartame have a metallic taste) as a result.
Besides the difference in taste between diet coke and coke zero, diet coke has 30% more caffeine (3.8 mg / oz vs 2.9 mg / oz): http://www.energyfiend.com/the-c...