What are the recommended glycemic targets for adults with a history of hypertension, diabetes, hyperlipidemia, or other cardiovascular risk factors admitted with acute stroke?

Glycemic Targets for Acute Stroke Patients

For patients admitted with acute stroke, initiate insulin therapy when blood glucose persistently exceeds 180 mg/dL and maintain glucose levels between 140-180 mg/dL, avoiding both aggressive lowering and hypoglycemia. 1, 2

Treatment Threshold and Target Range

• Start insulin therapy at 180 mg/dL: Insulin should be initiated when blood glucose persistently exceeds 180 mg/dL, regardless of diabetes history 1, 2
• Target range is 140-180 mg/dL: Once insulin is started, maintain glucose between 140-180 mg/dL for all critically ill stroke patients, including those with diabetes 1, 2, 3
• This moderate target applies to both ischemic and hemorrhagic stroke patients 1

Why Avoid Aggressive Glucose Lowering

The evidence strongly argues against targeting normoglycemia or levels below 140 mg/dL:

• No proven benefit from tight control: The GIST-UK trial, the only large randomized study testing aggressive glucose lowering in acute stroke, showed no improvement in clinical outcomes 2
• Increased mortality with tight control: Meta-analyses of over 26 studies, including the NICE-SUGAR trial, demonstrated increased rates of severe hypoglycemia (blood glucose <40 mg/dL) and higher mortality in tightly controlled cohorts compared to moderate control 1, 2
• Risk of permanent brain damage: Hypoglycemia can cause irreversible neurological injury and worsen ischemic damage in the already vulnerable post-stroke brain 2, 3

Critical Hypoglycemia Management

• Treat hypoglycemia immediately: Blood glucose below 60 mg/dL must be corrected urgently in all acute stroke patients 1, 3
• Hypoglycemia is particularly dangerous in the post-stroke period and represents a greater immediate threat than moderate hyperglycemia 2, 3

Rationale for Treatment

While treating hyperglycemia is important, the evidence base has important nuances:

• Association vs. causation: Persistent hyperglycemia during the first 24 hours after stroke is consistently associated with worse outcomes, increased infarct volume, hemorrhagic transformation, and higher mortality 1, 2, 4
• No proven intervention benefit: Despite strong observational associations, there is currently no clinical trial evidence that actively lowering glucose to any particular level improves stroke outcomes 2
• Treat to avoid extremes: The recommendation to maintain 140-180 mg/dL is based on avoiding the proven harms of both severe hyperglycemia and hypoglycemia, rather than proven benefits of glucose normalization 1, 2

Practical Implementation

Monitoring Frequency

• Check blood glucose on admission and document levels to assess severity 1
• Monitor every 1-2 hours initially during acute phase when using insulin 3, 5
• Continuous glucose monitoring studies reveal that many stroke patients experience undetected hypoglycemic events, particularly at night, even with normal admission glucose 4

Insulin Administration

• Intravenous insulin preferred for: Patients with extreme hyperglycemia (>180 mg/dL), critically ill patients, those receiving thrombolytic therapy, or hemodynamically unstable patients 3, 6
• Subcutaneous protocols acceptable for: Stable patients with moderate hyperglycemia can be safely managed with subcutaneous insulin protocols 2, 6
• Use regular insulin at 1 unit/mL concentration with initial infusion rates around 0.5 units/hour, adjusted to maintain the 140-180 mg/dL target 3, 5

Common Pitfalls to Avoid

• Never target normoglycemia (<140 mg/dL): This increases hypoglycemia risk without proven benefit and can cause permanent brain damage 1, 2, 3
• Don't delay treatment of severe hyperglycemia: While aggressive lowering is harmful, persistent hyperglycemia above 180 mg/dL during the first 24 hours is associated with poor outcomes and should be treated 1, 2
• Avoid "sliding scale" insulin alone: Use standardized protocols with basal insulin coverage rather than reactive correction-only approaches 6
• Watch for nocturnal hypoglycemia: Hypoglycemic events occur frequently at night even in patients with normal daytime glucose levels 4

Special Populations

• Patients with well-controlled diabetes: May tolerate slightly lower targets (closer to 140 mg/dL), but levels below 80 mg/dL should always be avoided 6
• Stress hyperglycemia without known diabetes: Treat the same as diabetic patients using the 140-180 mg/dL target 1, 6
• Patients on thrombolytic therapy: Admission hyperglycemia is associated with increased risk of symptomatic intracranial hemorrhage in rtPA-treated patients, making glucose control particularly important 2