What are the necessary baseline blood tests and imaging studies for a patient with a history of cerebrovascular infarct and type 2 diabetes before starting Glucagon-Like Peptide-1 (GLP1) Receptor Agonists (GLP1 RAs) therapy?

Baseline Testing Before Starting GLP-1 Receptor Agonists

Before initiating GLP-1 RA therapy in a patient with type 2 diabetes and prior cerebrovascular infarct, obtain baseline HbA1c, eGFR with UACR, and screen for personal or family history of medullary thyroid carcinoma or MEN2 syndrome—no routine imaging is required unless specific contraindications are suspected.

Mandatory Blood Tests

Essential Laboratory Assessment

• HbA1c measurement is required to establish baseline glycemic control, as most cardiovascular outcome trials enrolled patients with HbA1c ≥6.5-7.0% 1
• Serum creatinine with calculated eGFR must be obtained, though no dose adjustment is needed for renal impairment with GLP-1 RAs 2
• Urine albumin-to-creatinine ratio (UACR) should be measured at baseline to identify patients with albuminuria who may experience additional renal benefits 1

Additional Recommended Tests

• Fasting lipid panel is appropriate given the patient's established cardiovascular disease, as lipid management remains a cornerstone of secondary prevention 1
• Liver function tests should be considered, particularly if the patient has obesity or metabolic syndrome 1

Critical Safety Screening (Not Blood Tests)

Mandatory History Taking

• Ask every patient about personal history of medullary thyroid carcinoma (MTC) or family history of MTC in first-degree relatives before prescribing any GLP-1 RA, as this identifies potential MEN2 cases 3
• Screen for family history of pheochromocytoma, which raises suspicion for MEN2 even without known thyroid disease 3
• Inquire about oral or ocular neuromas (lips, tongue, sclera, eyelids) and diffuse ganglioneuromatosis or chronic constipation since childhood, as these suggest MEN2B 3

When to Order RET Genetic Testing

• If family history is positive or suspicious for MEN2, do not prescribe GLP-1 RA until RET germline mutation testing is completed—if RET mutation is confirmed, GLP-1 RAs are permanently contraindicated 3
• Remember that 40-50% of MEN2B cases arise from de novo mutations, so negative family history does not eliminate risk 3

Imaging Studies

No Routine Imaging Required

• No baseline imaging studies are mandated before starting GLP-1 RA therapy 1
• A resting ECG is indicated in patients with diabetes and hypertension or if cardiovascular disease is suspected, but this is for general cardiovascular risk assessment rather than a specific GLP-1 RA requirement 1

Optional Risk Stratification Imaging

• Transthoracic echocardiography, coronary artery calcium score, or ankle-brachial index may be considered as risk modifiers in those at moderate or high cardiovascular risk, but these are not prerequisites for GLP-1 RA initiation 1

Special Considerations for This Patient

Cerebrovascular Disease Context

• This patient with prior cerebrovascular infarct has established atherosclerotic cardiovascular disease (ASCVD), making GLP-1 RAs particularly appropriate as they reduce major adverse cardiovascular events (MACE) with the strongest evidence in this population 1
• GLP-1 RAs reduce the risk of recurrent ischemic stroke (RR 0.73,95% CI 0.60-0.89) and composite ischemic stroke/TIA (RR 0.76,95% CI 0.65-0.90), with benefits most pronounced in longer-acting formulations 4
• The cardiovascular benefits are independent of baseline HbA1c and concomitant glucose-lowering medications 1

Medication Interaction Assessment

• If the patient takes medications with narrow therapeutic indices (e.g., carbamazepine for seizure prophylaxis post-stroke), obtain baseline drug levels and monitor 2-4 weeks after each GLP-1 RA dose escalation due to delayed gastric emptying 2

Common Pitfalls to Avoid

• Never assume sporadic MTC is truly sporadic—always test for RET mutations as 25% have germline mutations 3
• Do not rely solely on family history for MEN2 screening—up to 50% of MEN2B cases are de novo mutations 3
• Do not order thyroid ultrasound or calcitonin levels routinely before GLP-1 RA initiation—these are not recommended screening tests and may lead to unnecessary interventions 3
• Do not delay GLP-1 RA initiation for extensive cardiovascular imaging in patients with established ASCVD, as the cardiovascular benefits are well-established and time to treatment matters 1