Laboratory Tests Required Before Starting Tirzepatide
Before prescribing tirzepatide for type 2 diabetes, you must obtain hemoglobin A1c, serum creatinine with eGFR, and urine albumin-to-creatinine ratio. 1
Essential Baseline Laboratory Tests
Glycemic Assessment
- Hemoglobin A1c (HbA1c) is mandatory to establish baseline glycemic control and determine treatment targets 1
- If the patient is already on diabetes therapy, HbA1c should be measured quarterly when therapy is being changed or targets are not met 1
- For patients meeting glycemic targets, HbA1c should be checked at least twice yearly 1
Renal Function Assessment
- Serum creatinine and estimated glomerular filtration rate (eGFR) are essential for assessing baseline kidney function 1
- Urine albumin-to-creatinine ratio must be performed annually in all patients with type 2 diabetes at diagnosis 1
- This is particularly important because patients with eGFR <30 mL/min/1.73 m² may benefit preferentially from GLP-1 receptor agonists like tirzepatide over SGLT-2 inhibitors 1
- Notably, no dose adjustment of tirzepatide is required across all stages of CKD, including eGFR <30 mL/min/1.73 m² 2
Additional Clinical Evaluations
Cardiovascular and Blood Pressure Monitoring
- Blood pressure should be determined at each visit in adult patients with type 2 diabetes 1
- An electrocardiogram should be obtained if clinically indicated 1
Ophthalmologic Assessment
- A comprehensive dilated eye examination should be performed shortly after type 2 diabetes diagnosis 1
Critical Pre-Treatment Medication Review
Hypoglycemia Risk Mitigation
- Review and adjust concomitant medications before starting tirzepatide to minimize hypoglycemia risk 1
- Discontinue or reduce sulfonylurea doses by 50% when initiating tirzepatide due to increased hypoglycemia risk 2
- Discontinue DPP-4 inhibitors before starting tirzepatide, as concurrent use provides no additional benefit 2, 1
- Reduce insulin dosing when adding tirzepatide to existing insulin therapy to minimize hypoglycemia risk 2, 1
- Never combine with other GLP-1 receptor agonists—this is pharmacologically redundant and potentially harmful 2
Monitoring During Treatment
- If using ACE inhibitors, ARBs, or diuretics, monitor serum creatinine and potassium levels 1
Common Pitfalls to Avoid
- Do not delay treatment modification for adults who are not meeting individualized treatment targets 1
- Do not rely solely on HbA1c in conditions with increased red blood cell turnover (sickle cell disease, pregnancy, hemodialysis, recent blood loss/transfusion, erythropoietin therapy)—use plasma glucose criteria instead 3
- Do not skip the urine albumin-to-creatinine ratio—this is required annually and helps guide medication selection 1
- Do not forget to assess for contraindications including personal or family history of medullary thyroid cancer or MEN2, and use cautiously in patients with history of pancreatitis 4