Prognostic Value of Admission Hyperglycemia on Outcomes of Thrombolysis in Ischemic Stroke Patients With or Without Diabetes
Thrombolytic therapy—given within 4.5 hours of symptom onset—is the gold standard for treating acute ischemic stroke (AIS), but nearly 40% of patients still face poor recovery or death. A critical, unresolved question hangs over this life-saving treatment: Does high blood sugar at admission (admission blood glucose, ABG) influence how well patients respond? And does having diabetes change that relationship?
A 2020 study published in the Chinese Medical Journal set out to answer these questions by analyzing data from over 1,000 AIS patients who received thrombolysis (rtPA) in China. Led by researchers from Beijing Tiantan Hospital and Capital Medical University, the study addressed a key gap in prior research: most studies didn’t separate patients with and without diabetes—even though ABG means very different things for each group. For non-diabetics, high ABG usually signals acute stress (like a stroke), while for diabetics, it may reflect long-term glucose control.
How the Study Worked
The team used data from the Thrombolysis Implementation and Monitor of Acute Ischemic Stroke in China (TIMS-China) registry, which tracked 1,440 AIS patients from 2000 to 2008. They narrowed the sample to 1,084 patients with:
- ABG measured before thrombolysis
- A known diabetes history (17.6% had diabetes, defined by prior diagnosis or use of insulin/oral hypoglycemics)
Using American Diabetes Association (ADA) guidelines, they categorized ABG levels:
- Normal: <7.8 mmol/L (140 mg/dL)
- Hyperglycemia: ≥7.8 mmol/L
- Severe hyperglycemia: ≥11.1 mmol/L (200 mg/dL)
They measured key outcomes:
- 90-day functional recovery: Using the modified Rankin Scale (mRS), a tool to assess disability (scores 0–2 = independent; 3–6 = disabled/dead).
- Mortality: 7-day and 90-day death from any cause.
- Early neurological deterioration (END): A ≥4-point jump in stroke severity (per the NIH Stroke Scale) within 24 hours.
- Symptomatic intracranial hemorrhage (sICH): Dangerous bleeding in the brain within 36 hours of thrombolysis (defined by the SITS-MOST criteria).
Key Findings
The results revealed a striking divide between diabetic and non-diabetic patients:
1. Non-Diabetic Patients: Severe Hyperglycemia Predicts Poor Outcomes
For patients without diabetes, high ABG—especially severe hyperglycemia (≥11.1 mmol/L)—was strongly tied to worse results:
- 4x higher risk of END (sudden worsening of symptoms)
- 4.25x higher risk of 7-day death
- 3.7x higher risk of 90-day death
Even after adjusting for other factors (like age, stroke severity, and blood pressure), these risks remained significant. Severe hyperglycemia also raised the chance of long-term disability (mRS 3–6), though this wasn’t statistically significant.
2. Diabetic Patients: ABG Doesn’t Predict Outcomes
For patients with diabetes, high ABG didn’t correlate with worse recovery or death—even when glucose levels were severely elevated. The study found no link between ABG and END, mortality, or disability in this group.
3. Diabetes History Raises Bleeding Risk
While ABG didn’t affect bleeding risk, having diabetes did: Diabetic patients were 2.5x more likely to develop sICH (3.7% vs. 1.5% in non-diabetics). This suggests chronic diabetes—not acute high blood sugar—drives bleeding risk, likely due to long-term damage to small brain blood vessels (microvascular injury).
Why the Difference?
The researchers offer two key explanations for the diabetic/non-diabetic divide:
- Stress vs. adaptation: For non-diabetics, high ABG is a sign of severe stress, which worsens brain damage. For diabetics, long-term exposure to high glucose may make their bodies more resilient to acute spikes.
- Chronic vs. acute damage: Diabetes causes slow, cumulative harm to brain blood vessels (via “glucose toxicity”). This makes diabetic patients more prone to bleeding after thrombolysis—even if their ABG is normal.
Limitations to Consider
The study has important caveats:
- Retrospective design: Researchers used existing data, so they couldn’t control for all variables (like fasting blood sugar or hemoglobin A1c, which reflects long-term glucose control).
- Diabetes diagnosis: Some cases may have been missed, as the study relied on patient history or medication use (not lab tests).
- Small sample of severe hyperglycemia: Only 9% of patients had ABG ≥11.1 mmol/L, limiting the power to draw conclusions for this group.
What This Means for Patients and Doctors
The findings have clear clinical takeaways:
- For non-diabetic AIS patients: Controlling admission hyperglycemia—especially severe levels (≥11.1 mmol/L)—could improve thrombolysis outcomes. Doctors should monitor ABG closely and consider interventions (like insulin) if levels are very high.
- For diabetic AIS patients: While ABG may not predict outcomes, diabetes itself raises sICH risk. Doctors should be extra cautious when offering thrombolysis and watch closely for bleeding complications.
The study also highlights a need for more research on glucose targets for diabetic stroke patients. Prior work (like Snarska et al., 2017) suggests diabetics may have a higher “safe” ABG threshold for poor outcomes—something future studies should explore.
About the Researchers
The study was led by Hong-Juan Fang (Department of Endocrinology, Beijing Tiantan Hospital) and Yue-Song Pan (Department of Neurology, Beijing Tiantan Hospital), with contributions from experts at the China National Clinical Research Center for Neurological Diseases and the Beijing Institute for Brain Disorders.
This study was published in the Chinese Medical Journal (2020;133(18)).
doi.org/10.1097/CM9.0000000000001005
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