The role of stress-induced hyperglycemia in acute coronary syndromes: pathophysiology, novel markers and clinical implications.

Stress-Induced Hyperglycemia (SIH) represents a transient increase in blood glucose levels triggered by acute physiological stress, frequently observed in patients with Acute Coronary Syndrome (ACS). It is linked to adverse outcomes, including higher mortality and an increased risk of Major Adverse Cardiac and Cerebrovascular Events (MACCE). Despite this, SIH remains inadequately defined and underappreciated in clinical risk assessment and patient management. This narrative review delves into the mechanistic underpinnings of SIH in ACS (neuroendocrine, metabolic and inflammatory pathways). Evidence on current SIH markers including the Stress-Hyperglycemia Ratio (SHR), Admission Blood Glucose, Glycemic Gap, and Glycemic Variability was identified through searches of PubMed/MEDLINE for English-language human studies published between January 2017 and May 2025 (certain seminal earlier studies were also retained), with a focus on key subpopulations (diabetes, non-diabetes, and MINOCA). Particular emphasis is placed on SHR as a ratio of acute to chronic hyperglycemia with expanding prognostic applications. SIH is a multifaceted phenomenon, superiorly reflected by dynamic indices like SHR rather than traditional measures. Further research into the mechanisms linking SIH with adverse outcomes could lay the groundwork for interventional trials, ultimately reshaping ACS patient risk-stratification and management.