What routine blood tests and imaging studies are recommended for a patient with type 2 diabetes (T2D) prior to starting Glucagon-like peptide-1 receptor agonist (GLP-1 RA) medications?

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Routine Testing Prior to Starting GLP-1 RA Medications

No specific routine blood tests or imaging studies are required before initiating GLP-1 RA therapy in patients with type 2 diabetes. 1

Essential Pre-Treatment Assessment

Eye Examination (Critical Requirement)

  • Patients must undergo appropriate, guideline-recommended eye examinations before starting therapy if not completed within the last 12 months 1
  • This is particularly important for dulaglutide and injectable semaglutide due to potential risk of diabetic retinopathy complications 1
  • Semaglutide specifically has been associated with increased risk of diabetic retinopathy complications, predominantly in patients with prior history of proliferative retinopathy 1

Clinical Contraindications to Assess

  • Avoid GLP-1 RAs in patients with diabetic gastroparesis or active gallbladder disease 1
  • Screen for history of pancreatitis, as GLP-1 RAs may increase risk of gallbladder disease including acute cholecystitis 1
  • Assess for severe renal impairment or end-stage renal disease, particularly for liraglutide and semaglutide 1

Medication Adjustments Before Initiation

Discontinue Conflicting Medications

  • Discontinue DPP-4 inhibitors before starting GLP-1 RA therapy 1
  • These medications work through the same GLP-1 signaling pathway and have not been approved for concurrent use 1

Hypoglycemia Risk Mitigation

  • If HbA1c is well-controlled at baseline or patient has history of frequent hypoglycemic events, wean or stop sulfonylurea 1
  • For patients taking insulin, consider modestly reducing total daily insulin dose by up to 20% when starting therapy 1
  • Instruct patients to more closely monitor glucose at home for the first 4 weeks of therapy 1
  • Consider discontinuing any glinide medication 1

Monitoring Strategy (Not Pre-Treatment Testing)

Post-Initiation Monitoring

  • Monitor blood glucose more frequently during the first 4 weeks, especially if on insulin, sulfonylurea, or glinides 1
  • No specific laboratory monitoring is required for GLP-1 RA therapy itself 1

Common Pitfalls to Avoid

  • Do not delay GLP-1 RA initiation waiting for unnecessary laboratory tests or imaging studies 1
  • The only mandatory pre-treatment assessment is the eye examination if not done within 12 months 1
  • Do not forget to discontinue DPP-4 inhibitors, as this is a critical medication interaction 1
  • Do not fail to reduce insulin or sulfonylurea doses proactively, as this significantly increases hypoglycemia risk 1
  • Ensure patients understand that transient nausea is common and can be minimized by starting at the lowest dose, up-titrating gradually, and eating smaller portions 1

References

Guideline

Guideline Directed Topic Overview

Dr.Oracle Medical Advisory Board & Editors, 2025

Professional Medical Disclaimer

This information is intended for healthcare professionals. Any medical decision-making should rely on clinical judgment and independently verified information. The content provided herein does not replace professional discretion and should be considered supplementary to established clinical guidelines. Healthcare providers should verify all information against primary literature and current practice standards before application in patient care. Dr.Oracle assumes no liability for clinical decisions based on this content.

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