CGM-Based Glycemic Analysis After ESI

Epidural steroid injections (ESIs) are a widely used non-surgical treatment for radicular pain caused by spinal conditions such as herniated discs and spinal stenosis. While effective for pain relief, the systemic absorption of corticosteroids (e.g., dexamethasone) can induce temporary hyperglycemia, which poses potential risks, particularly for patients with type 2 diabetes mellitus (T2DM).

Previous studies on post-ESI hyperglycemia have largely relied on self-monitoring of blood glucose (SMBG), which captures only intermittent glucose data and may miss significant glycemic excursions, such as postprandial spikes or nocturnal hypoglycemia. This study aims to overcome these limitations by using a Continuous Glucose Monitoring (CGM) system to provide a comprehensive, time-series analysis of glycemic fluctuations.

Objectives:

To compare glycemic changes (mean glucose, Time in Range [TIR], Time Above Range [TAR]) following an epidural steroid injection with 5 mg of dexamethasone between a type 2 diabetes group and a non-diabetes control group.

To investigate the correlation between baseline HbA1c levels and the magnitude of post-injection glycemic variability.

Study Design: This is a prospective, observational, comparative study conducted at a single center (Korea University Anam Hospital). A total of 36 participants (18 in the T2DM group and 18 in the Non-DM group) will be enrolled.

Study Procedures:

Visit 1 (Day 1 - Screening & Baseline):

• Participants provide informed consent and undergo screening.
• Baseline HbA1c is measured.
• A CGM sensor (Abbott FreeStyle Libre 2) is attached to the participant's upper arm.
• Participants receive education on CGM use and are instructed to maintain their usual diet and medication.
• Baseline Data Collection: Glucose levels are monitored for 2 days (Day 1-2) to establish a baseline profile before the injection.

Visit 2 (Day 3 - Intervention):

• Participants undergo the scheduled epidural steroid injection (cervical or lumbar) using 5 mg of dexamethasone.
• The procedure is performed under fluoroscopic guidance according to standard clinical practice.

Visit 3 (Day 15 - Follow-up & Data Collection):

• Participants return to the clinic for follow-up.
• The CGM sensor is removed, and the stored glycemic data is downloaded.
• Pain intensity (Numeric Rating Scale, NRS) and any adverse events are recorded.

Statistical Analysis: The primary endpoints (changes in mean daily glucose and TIR) will be analyzed using a Linear Mixed Model (LMM) to account for repeated measures. Fixed effects will include Group (DM vs. Non-DM), Time (Baseline vs. Post-injection), and the Group-by-Time interaction. Patient demographics (e.g., age, BMI) will be included as covariates if significant differences are observed at baseline. A p-value of <0.05 will be considered statistically significant.

This study will provide high-resolution data on the duration and severity of steroid-induced hyperglycemia, contributing to safer pain management protocols for diabetic patients.

Inclusion criteria

• Adults aged 20 to 60 years.
• Patients scheduled for cervical or lumbar epidural steroid injection at the pain clinic.
• Patients capable of understanding and using a Continuous Glucose Monitoring (CGM) device.

Exclusion criteria

• Patients currently taking or administering steroid medications.
• Patients with Type 1 Diabetes Mellitus.
• Patients with Cushing's disease.
• Patients who have received an epidural steroid injection within the last 3 months.
• Patients with a known allergy to contrast media.
• Patients taking anticoagulants or antiplatelet agents.
• Patients unable to use a Continuous Glucose Monitoring (CGM) device.