What blood sugar readings are alarming and require immediate hospital attention, especially for adults with a history of diabetes-related complications?

Alarming Blood Sugar Readings Requiring Hospital Attention

You should go to the hospital immediately if your blood sugar is below 54 mg/dL (3.0 mmol/L) or above 250-300 mg/dL (13.9-16.7 mmol/L), especially if accompanied by symptoms like vomiting, confusion, or inability to eat or drink. 1, 2, 3

Critical Low Blood Sugar (Hypoglycemia)

Levels Requiring Immediate Action

• Blood glucose below 54 mg/dL (3.0 mmol/L) represents Level 2 hypoglycemia—the threshold where neuroglycopenic symptoms begin and requires immediate action 1
• Level 3 hypoglycemia occurs when you experience severe cognitive impairment, altered mental status, seizures, unconsciousness, or inability to treat yourself, regardless of the actual glucose number 1
• Blood glucose between 54-70 mg/dL (3.0-3.9 mmol/L) is Level 1 hypoglycemia and warrants treatment with fast-acting carbohydrates, but may not require hospital care if you can self-treat 1

Warning Signs Requiring Emergency Care

The FDA insulin label identifies these severe hypoglycemia symptoms requiring immediate medical assistance: 3

• Disorientation or confusion
• Seizures
• Unconsciousness
• Inability to take sugar orally

Common pitfall: Early warning symptoms of hypoglycemia may be diminished or absent in patients with long-standing diabetes, those on beta-blockers, or after switching insulin types, making you unable to recognize dangerous drops before severe symptoms occur 3

Critical High Blood Sugar (Hyperglycemia)

Levels Requiring Hospital Evaluation

• Blood glucose persistently above 250 mg/dL (13.9 mmol/L) warrants medical evaluation, particularly if you have type 1 diabetes 1, 2
• Blood glucose above 300 mg/dL (16.7 mmol/L) combined with symptoms requires immediate emergency care 2, 4
• The American Diabetes Association defines hyperglycemia requiring intervention at ≥180 mg/dL (10.0 mmol/L) in hospitalized patients, though this threshold is for inpatient management rather than home emergency decisions 1

Red Flag Symptoms Indicating Diabetic Ketoacidosis (DKA)

Go to the hospital immediately if high blood sugar is accompanied by: 2, 4, 3, 5

• Vomiting with ketosis—this combination strongly indicates DKA requiring immediate intervention 2, 4
• Presence of moderate to large ketones in urine or blood
• Fruity odor on breath
• Drowsiness or difficulty staying awake
• Flushed face
• Extreme thirst despite drinking fluids
• Heavy or rapid breathing
• Abdominal pain
• Loss of appetite

DKA Diagnostic Criteria

The American Diabetes Association defines DKA as: 2, 5

• Blood glucose >250 mg/dL (13.9 mmol/L)
• Arterial pH <7.3
• Bicarbonate <15 mEq/L
• Moderate ketonemia or ketonuria

Critical warning: SGLT2 inhibitor users can develop euglycemic DKA with normal or near-normal glucose levels (sometimes <200 mg/dL), so ketone testing and symptom recognition are essential even when glucose isn't extremely elevated 2

Special Circumstances Requiring Lower Threshold for Hospital Care

When to Seek Care Even with Moderately Elevated Glucose

Seek immediate medical attention if: 2, 4, 3

• You are vomiting and cannot keep down fluids or medications, even if glucose is only moderately elevated (>200 mg/dL)
• You are pregnant with any concern for hyperglycemia or ketosis—significant feto-maternal harm can occur 2
• You have persistent symptoms despite home treatment attempts
• You are unable to take your insulin due to illness 4, 3

Sick Day Management Failures

The FDA insulin label emphasizes that illness may cause insulin requirements to change, and you still require insulin even if not eating 3. Go to the hospital if:

• Blood glucose remains >300 mg/dL despite taking correction insulin 2
• You detect ketones and glucose is >200-300 mg/dL 4, 3
• You cannot maintain hydration due to vomiting 4

Practical Action Algorithm

For Low Blood Sugar:

1. If glucose 54-70 mg/dL: Consume 15-20g fast-acting carbohydrates, recheck in 15 minutes 1
2. If glucose <54 mg/dL: Treat immediately and consider calling for help 1
3. If unable to swallow or unconscious: Call 911 immediately—glucagon injection or IV glucose needed 3

For High Blood Sugar:

1. If glucose 180-250 mg/dL without symptoms: Take correction insulin, increase fluids, recheck in 2-4 hours 1
2. If glucose >250 mg/dL: Check ketones immediately 2, 3
3. If ketones present OR glucose >300 mg/dL with symptoms: Go to emergency department 2, 4
4. If vomiting with any ketones: Go to emergency department immediately 2, 4

Critical pitfall to avoid: Never discontinue insulin during illness, even if you're not eating—this is a common trigger for DKA 4, 3. The combination of stopping insulin and being unable to eat creates a perfect storm for ketoacidosis development.