Why Glucose is Checked in Emergency Department Chest Pain Patients
Glucose measurement in chest pain patients serves three critical purposes: identifying undiagnosed diabetes that masquerades as "stress hyperglycemia," risk-stratifying patients for adverse cardiac outcomes, and detecting a powerful independent predictor of mortality in acute coronary syndrome.
Primary Diagnostic Function: Unmasking Hidden Diabetes
Admission hyperglycemia (≥10 mmol/L or ≥180 mg/dL) in chest pain patients typically indicates previously undiagnosed diabetes rather than true stress response. In patients presenting with suspected myocardial infarction, 63% of those with admission glucose ≥10 mmol/L had confirmed diabetes on follow-up glucose tolerance testing at 2 months, and an additional 6% had impaired glucose tolerance 1
Elevated glycosylated hemoglobin (HbA1c >7.5%) on admission confirms pre-existing diabetes in these patients, proving the hyperglycemia preceded the acute event 1
There is no evidence that myocardial infarction itself precipitates diabetes—the elevated glucose reflects chronic dysglycemia that was simply unrecognized 1
Risk Stratification for Major Adverse Cardiac Events (MACE)
Admission glucose >7 mmol/L (126 mg/dL) is an independent predictor of MACE within 30 days (OR 1.51,95% CI 1.06-2.14) in patients presenting with suspected acute coronary syndrome 2
Among 1,708 emergency department chest pain patients, 27.9% had hyperglycemia (>7 mmol/L), and 30.9% of these hyperglycemic patients experienced a MACE compared to lower rates in normoglycemic patients 2
Hyperglycemia should be considered alongside traditional risk factors (age, gender, hypertension, dyslipidemia, ischemic ECG changes, positive troponin) when stratifying chest pain patients 2
Prognostic Marker for In-Hospital Mortality
Admission hyperglycemia (>11 mmol/L or 198 mg/dL) in acute myocardial infarction patients undergoing percutaneous coronary intervention increases in-hospital mortality regardless of diabetes history 3
Non-diabetic patients with admission hyperglycemia had 11.5% in-hospital mortality versus 2.6% in non-diabetic normoglycemic patients (OR 2.29,95% CI 1.10-5.49) 3
Diabetic patients with admission hyperglycemia had 8.8% mortality (OR 2.14,95% CI 1.14-4.69), while diabetic patients without admission hyperglycemia had only 2.7% mortality—demonstrating that the acute glucose elevation, not the diabetes diagnosis itself, drives the risk 3
Clinical Context from Guidelines
The illustrative case in American College of Radiology guidelines describes a 54-year-old diabetic man presenting with chest pain whose fasting glucose of 275 mg/dL (15.3 mmol/L) was documented alongside ECG and cardiac enzymes as part of standard emergency evaluation 4
Point-of-care glucose testing provides rapid results (typically <2 minutes) that inform immediate triage decisions, though central laboratory methods remain the gold standard for accuracy in critical care settings 5
Public Health Opportunity Often Missed
In one study, 42% of emergency department patients with random glucose ≥150 mg/dL (8.3 mmol/L) and no prior diabetes diagnosis were discharged, but only 2.2% were informed of the elevation or referred for follow-up 6
The mean glucose in these unrecognized cases was 181.53 mg/dL, representing missed opportunities to identify the 79 million Americans with prediabetes 6
Common Pitfalls to Avoid
Do not dismiss hyperglycemia as merely "stress-related" without measuring HbA1c or arranging glucose tolerance testing—most cases represent undiagnosed chronic diabetes 1
Do not assume diabetic patients are at uniformly high risk—those without admission hyperglycemia have mortality rates equivalent to non-diabetics, so the acute glucose value matters more than the diagnosis 3
Do not fail to document and communicate elevated glucose findings to discharged patients—this represents a critical missed prevention opportunity 6