"Isn't ABL the only drug that has reduced cardiovascular death in diabetics?"
No. SGLT2 inhibitors and GLP-1R agonists, both diabetes drugs, have done this in recent CVOTs. Vascepa in REDUCE-IT was effective at reducing MACE in diabetics, though that trial was not all diabetic patients. These trials were not exclusively in high risk, recent ACS patients though. So these trials were not designed like BETonMACE.
The niche for Apabetalone is that it is the first trial to "almost" prove in BETonMACE to effectively reduce MACE in diabetics with recent ACS. Past trials like ELIXA, EXAMINE and ALE-CARDIO in similar recent ACS diabetic populations failed to even hint at reducing MACE.