Combined GLP-1 Receptor Agonist and SGLT2 Inhibitor Therapy for Adults with Type 2 Diabetes and Chronic Obstructive Pulmonary Disease: A Large-Scale Target Trial Emulation

Technical Summary: Combined GLP-1 Receptor Agonist and SGLT2 Inhibitor Therapy for Adults with Type 2 Diabetes and Chronic Obstructive Pulmonary Disease

Problem Statement

Adults with comorbid type 2 diabetes mellitus (T2DM) and chronic obstructive pulmonary disease (COPD) face substantial risks from overlapping cardiometabolic and respiratory pathways. While glucagon-like peptide-1 receptor agonists (GLP-1RAs) and sodium-glucose cotransporter 2 inhibitors (SGLT2is) are established to provide metabolic, cardiovascular, and renal benefits, the clinical outcomes of their combined use in this specific high-risk comorbid population remain uncertain. Existing literature suggests individual classes may influence respiratory outcomes (e.g., reducing COPD exacerbations), but it is unclear if initiating both classes simultaneously offers additive benefits regarding mortality and respiratory events compared to monotherapy.

Methodology

The authors conducted a large-scale target trial emulation using the TriNetX US Collaborative Network (2018–2023). The study employed a retrospective, new-user, active-comparator design to evaluate clinical outcomes in routine practice.

• Cohort Construction: The source population included 370,511 adults with both T2DM and COPD. Eligible participants were aged ≥18, had ≥3 healthcare encounters, and underwent a 6-month washout period for both drug classes.
  • Intervention Group: Patients initiating a combination strategy of GLP-1RA + SGLT2i (n = 18,774).
  • Comparator Group: Patients initiating SGLT2i monotherapy (n = 42,197).
  • Exclusions: Cancer, organ transplantation, dialysis, and death within 90 days of the index date.
• Study Design: A 90-day landmark analysis was implemented, meaning follow-up began 90 days after the index prescription date to ensure patient survival and treatment stability. The analysis followed an intention-to-treat-like approach, analyzing patients based on their initial strategy regardless of subsequent discontinuation or switching.
• Statistical Analysis:
  • Matching: 1:1 propensity score matching (greedy nearest-neighbor, caliper 0.1) balanced demographics, socioeconomic/lifestyle factors, comorbidities, medications, laboratory parameters, and healthcare utilization proxies.
  • Outcomes: The primary outcome was all-cause mortality. Key secondary outcomes included COPD exacerbation and pneumonia. Other outcomes included dialysis initiation, major adverse cardiovascular events (MACE), emergency department (ED) visits, and hospitalization.
  • Metrics: Hazard ratios (HR) with 95% confidence intervals (CI) were generated via Cox proportional hazards models. Absolute risk reductions (ARR), number needed to treat (NNT), and restricted mean survival time differences (RMSTD) were calculated to assess clinical impact.
  • Sensitivity: Analyses included hierarchical matching models, varying follow-up horizons (1–3 years), E-value calculations for unmeasured confounding, and a secondary comparison against GLP-1RA monotherapy.

Key Results

After 1:1 propensity score matching, 17,467 patients were included in each group. The baseline characteristics were well-balanced (standardized mean differences < 0.1).

• All-Cause Mortality: The combination strategy was associated with a significantly lower risk of death compared to SGLT2i monotherapy (HR 0.86; 95% CI 0.81–0.93).
  • At 4 years, the absolute risk reduction (ARR) was 2.27%.
  • The Number Needed to Treat (NNT) to prevent one death over 4 years was 44.0.
• Respiratory Outcomes:
  • COPD Exacerbation: Lower risk in the combination group (HR 0.93; 95% CI 0.89–0.97). The 4-year ARR was 2.07% (NNT 48.4).
  • Pneumonia: Lower risk in the combination group (HR 0.93; 95% CI 0.89–0.98). The 4-year ARR was 1.59% (NNT 62.8).
• Other Outcomes: No statistically significant differences were observed between groups for dialysis initiation, MACE, ED visits, or hospitalization in the primary analysis.
• Secondary Comparison (vs. GLP-1RA Monotherapy): When compared to GLP-1RA monotherapy, the combination therapy also showed lower risks for mortality, COPD exacerbation, pneumonia, dialysis initiation, and MACE.
• Sensitivity: Results remained consistent across hierarchical matching models and cumulative follow-up horizons.

Significance and Claims

The paper claims that among adults with T2DM and COPD who survive the initial 90-day period, initiating GLP-1RA plus SGLT2i therapy is associated with modest but statistically significant reductions in all-cause mortality, COPD exacerbations, and pneumonia compared to SGLT2i initiation alone.

• Clinical Context: The authors emphasize that while the relative risk reductions are modest, the absolute risk reductions accumulate over time, offering meaningful clinical value for selected high-risk patients with established indications for both drug classes.
• Mechanistic Hypothesis: The study suggests that the two drug classes may act through complementary pathways (e.g., GLP-1RAs reducing airway inflammation and SGLT2is improving pulmonary vascular function), potentially yielding additive respiratory benefits, though direct biological synergy in COPD has not been established.
• Limitations: The authors explicitly note limitations including potential residual confounding, lack of direct COPD severity markers (e.g., spirometry), inability to confirm medication adherence, and the predominantly White US cohort, which may limit generalizability.
• Conclusion: The findings support further evaluation of combination therapy as a beneficial option for high-risk patients but do not establish it as a standard of care without prospective confirmation. Treatment decisions should integrate metabolic and cardiorenal indications alongside tolerability, access, and patient preference.