The results show that the drugs reduce the numbers. They do not show that this results in a reduction in long-term complications, which is what is really important.
Doctors and the FDA are starting to question this approach. The studies necessary to show meaningful results from taking these drugs would have to last decades. Obviously, the drug companies prefer the current system where they just have to show that the surrogate markers of the disease, the numbers, improve.
When you consider that every drug has side effects, and that the more drugs you take, the greater the risk, it would make sense to proceed with caution.
While I'm inclined to look for adverse drug reactions, they are usually dose related. They are probably starting this 3-drug combination with the lowest dose of each drug because hypoglycemia is a definite fear.
I've seen a low dose multiple drug approach recommended for high blood pressure also to avoid adverse drug reactions.
I believe in treating patients, not numbers, but if you have bad outcomes, and the patient's numbers are really bad, and the doc didn't try to correct those numbers, the doc might get sued for malpractice.