What is the best approach to manage hyperglycemia in a patient with type 2 diabetes mellitus (T2Dm) on metformin (Metformin), 12 hours post-admission for an acute left Middle Cerebral Artery (MCA) ischemic stroke, currently nil by mouth (NBM) with a capillary blood glucose (CBG) level of 12.2mmol/L?

Management of Hyperglycemia in Acute Ischemic Stroke

For this patient 12 hours post-acute ischemic stroke with CBG 12.2 mmol/L (220 mg/dL), initiate subcutaneous insulin therapy targeting blood glucose 7.8-10.0 mmol/L (140-180 mg/dL), discontinue metformin while NBM, and monitor glucose every 1-2 hours. 1

Immediate Actions

Discontinue Metformin

• Stop metformin immediately as the patient is nil by mouth (NBM) and cannot take oral medications 2
• Metformin requires oral intake and carries risk of lactic acidosis in acute illness settings 2

Initiate Insulin Therapy

• Start subcutaneous insulin regimen with basal long-acting insulin plus correction rapid-acting insulin for out-of-range glucose 3
• Target glucose range: 7.8-10.0 mmol/L (140-180 mg/dL) as recommended by the American Heart Association for acute stroke patients 4, 1
• This target balances hyperglycemia risks against hypoglycemia dangers in the acute stroke setting 4

Glucose Monitoring Protocol

• Check capillary blood glucose every 1-2 hours initially given the acute stroke and hyperglycemia 1, 3
• More frequent monitoring is critical in the first 24-48 hours post-stroke 3

Rationale for This Approach

Why Not Aggressive Glucose Lowering?

The GIST-UK trial demonstrated that targeting lower glucose levels in acute stroke did not improve outcomes and increased resource utilization 4. There is currently no clinical evidence that targeting blood glucose to a particular level during acute ischemic stroke will improve outcomes 4. The main risk from aggressive correction is hypoglycemia, which can cause permanent brain damage and mimic stroke symptoms 1, 5.

Why This Target Range?

• The American Diabetes Association recommends 7.8-10.0 mmol/L (140-180 mg/dL) for all hospitalized patients 4, 3
• Hyperglycemia >10 mmol/L (180 mg/dL) is associated with worse outcomes including increased hemorrhagic transformation risk and larger infarct volumes 4, 1
• However, overly aggressive lowering increases hypoglycemia risk without proven benefit 4

Specific Insulin Protocol

Basal-Bolus Regimen

• Start with basal long-acting insulin (e.g., glargine or detemir) at 0.1-0.2 units/kg/day 3
• Add correction-dose rapid-acting insulin (e.g., lispro, aspart) using a sliding scale for glucose >10 mmol/L (180 mg/dL) 3
• Once patient resumes eating, add prandial rapid-acting insulin before meals 3

Alternative: IV Insulin for Severe Cases

• Consider intravenous insulin infusion if glucose persistently >16.7 mmol/L (300 mg/dL) or patient is critically ill 4, 3
• IV insulin allows more precise titration but requires ICU-level monitoring 4
• Transition to subcutaneous insulin after 24-48 hours of stability 3

Critical Pitfalls to Avoid

Do Not Give Glucose-Containing IV Fluids

• Avoid dextrose-containing solutions as they worsen hyperglycemia 4, 1
• Use normal saline for hydration 1

Do Not Target Glucose <7.8 mmol/L (140 mg/dL)

• Aggressive lowering increases hypoglycemia risk without proven benefit in acute stroke 4, 1
• Hypoglycemia <3.3 mmol/L (60 mg/dL) can cause permanent brain injury 1, 5

Do Not Use Sliding-Scale Insulin Alone

• Sliding-scale insulin as sole therapy is inadequate for glucose control 5, 3
• Always include basal insulin component 3

Monitor for Hypoglycemia

• Check glucose immediately if patient develops altered mental status as hypoglycemia can mimic stroke progression 1, 5
• Have 50% dextrose available at bedside 1, 5

When to Resume Metformin

Criteria for Restarting

• Patient tolerating oral intake without dysphagia 2
• Hemodynamically stable with normal renal function (eGFR >30 mL/min/1.73m²) 2
• No acute illness or contrast procedures planned 2
• Typically after 48-72 hours if neurologically stable 2

Transition Strategy

• Continue basal insulin while reintroducing metformin 3
• Gradually reduce insulin doses as metformin reaches therapeutic levels 3
• Monitor glucose closely during transition period 3

Additional Stroke-Specific Considerations

Blood Pressure Management

• Do not aggressively lower blood pressure unless >220/120 mmHg, as this can extend infarct 1
• Maintain BP <180/105 mmHg if thrombolysis was given 1

Temperature Control

• Treat fever aggressively with antipyretics for temperature >37.5°C as fever worsens stroke outcomes 1

Cardiac Monitoring

• Continue cardiac monitoring for at least 24 hours to detect atrial fibrillation 1