Emergency Department Presentation Thresholds for Hyperglycemia
Patients should present to the emergency department when blood glucose exceeds 250 mg/dL (13.9 mmol/L) for two consecutive days, or immediately when glucose is ≥180 mg/dL with symptoms of severe hyperglycemia such as vomiting, dehydration, or altered mental status. 1
Immediate Emergency Evaluation Required
The following scenarios mandate immediate ED presentation:
Blood glucose ≥180 mg/dL with any of the following symptoms: 1
- Vomiting or inability to keep fluids down
- Signs of dehydration (dry mouth, decreased urination, dizziness)
- Altered mental status or confusion
- Severe illness or acute medical condition
Blood glucose ≥250 mg/dL persistently over 2 consecutive days, even without symptoms 1
Any glucose reading too high for home glucometer to measure (typically >600 mg/dL) 1
Signs of diabetic ketoacidosis (DKA) regardless of specific glucose level: 2
- Plasma glucose ≥250 mg/dL with arterial pH <7.30 and bicarbonate <15 mEq/L
- Moderate to large ketonuria or ketonemia
- Kussmaul respirations (deep, rapid breathing)
- Nausea, vomiting, or abdominal pain
Signs of hyperosmolar hyperglycemic state (HHS): 2
Special Population Considerations
Youth with Type 2 Diabetes
- Blood glucose ≥250 mg/dL with symptoms (polyuria, polydipsia, weight loss) warrants immediate evaluation 2
- Blood glucose ≥600 mg/dL requires assessment for hyperglycemic hyperosmolar nonketotic syndrome 2
- Any ketosis or ketoacidosis requires immediate insulin therapy and ED evaluation 2
Pregnant Individuals
- Any concern for DKA requires immediate medical attention due to significant feto-maternal harm risk 2
- Pregnant patients may present with euglycemic DKA (glucose <200 mg/dL), making clinical suspicion critical 2
- Up to 2% of pregnancies with pregestational diabetes are complicated by DKA 2
Patients on SGLT2 Inhibitors
- Glucose >200 mg/dL with ketones present should prompt immediate evaluation, as euglycemic DKA can occur 2
- Risk factors include very-low-carbohydrate diets, prolonged fasting, dehydration, and excessive alcohol intake 2
When Home Management May Be Attempted
Patients may attempt home management under specific conditions: 2
- Glucose >200 mg/dL with mild symptoms if:
- Hemodynamically stable and cognitively intact
- Able to tolerate oral hydration
- Able to administer subcutaneous insulin
- Can perform frequent blood glucose and ketone monitoring
- Have access to diabetes care team support
However, seek immediate medical attention if: 2
- Unable to tolerate oral hydration
- Blood glucose does not improve with insulin administration
- Altered mental status develops
- Any signs of worsening illness occur
Critical Thresholds for Institutional Notification
Correctional and institutional settings should implement policies requiring physician notification for: 2
- Blood glucose <50 mg/dL or >350 mg/dL (<2.8 or >19.4 mmol/L) 2
- These thresholds can be adapted to other supervised settings
Common Pitfalls to Avoid
- Do not dismiss glucose >200 mg/dL in patients with symptoms, even if they have chronic poor control—this may represent acute decompensation 2
- Do not wait for classic DKA symptoms in pregnant patients, as presentation may be atypical with euglycemic DKA 2
- Do not assume patients on SGLT2 inhibitors are safe from DKA if glucose is <250 mg/dL—euglycemic DKA can occur 2
- Do not delay evaluation in patients unable to contact their diabetes care team—readily available clinical support can prevent emergency care, but its absence should prompt ED presentation 2
The evidence strongly supports a lower threshold for ED presentation when symptoms are present, as admission hyperglycemia (particularly >200 mg/dL) is associated with increased mortality and adverse outcomes in patients without known diabetes 3, 4. The American Diabetes Association guidelines consistently emphasize that symptom presence lowers the threshold for emergency evaluation, even at glucose levels that might otherwise be managed outpatient 1.