Newly diagnosed versus previously diagnosed or no diabetes mellitus in patients with acute coronary syndrome: a systematic review and meta-analysis

Νewly diagnosed diabetes mellitus (NDDM) among acute coronary syndrome (ACS) patients represents a distinct clinical entity, although available data remain inconclusive. This systematic review and meta-analysis compared ACS patients with NDDM to those without diabetes mellitus (DM) and those with previously diagnosed DM (PDDM). We searched PubMed, Scopus, and CENTRAL until 10 December 2024. We assessed myocardial necrosis, prognosis, coronary artery disease (CAD) extent, left ventricular ejection fraction (LVEF) at discharge, and cardiometabolic profiles. ROBINS-E and GRADE assessed bias risk and evidence certainty, respectively. Out of 257,859 ACS patients from 34 studies, 5.2% had NDDM. NDDM patients had higher mean peak hs-cardiac troponin I levels compared to PDDM patients (MD 18,389.15 [95% CI 2975.96, 33802.34]) and intermediate post-discharge prognosis between PDDM and non-DM patients [5-MACE; RR 0.80 (95% CI 0.71, 0.91); RR 1.21 (95% CI 1.08, 1.37), respectively]. NDDM patients had similar discharge LVEF to PDDM patients but lower than non-DM patients (MD -2.06% [95% CI -2.93, -1.18]). Their cardiometabolic profile resembled PDDM. Although the evidence was mostly low-certainty, the high prevalence of NDDM and its potentially unfavorable outcomes compared to non-DM patients could stimulate further research on the effects of intensified DM screening and preventive measures in the community and among ACS patients This systematic review and meta-analysis was registered with PROSPERO (CRD42024501412).