Tirzepatide Blood Work Guide: What to Track on GIP/GLP-1 Therapy

Why Blood Work Matters on Tirzepatide

Tirzepatide is a dual GIP/GLP-1 receptor agonist studied in the SURMOUNT and SURPASS clinical trial programs. Unlike semaglutide which targets only GLP-1 receptors, tirzepatide activates both GIP and GLP-1 pathways. This dual mechanism affects multiple biomarker systems simultaneously, making blood work monitoring essential.

Core Biomarkers to Track

### Metabolic Panel

Fasting glucose and HbA1c are the primary efficacy markers. Research from the SURPASS trials showed significant reductions in HbA1c across all dose groups studied. Fasting insulin and HOMA-IR provide additional context about insulin resistance.

### Lipid Panel

Total cholesterol, LDL, HDL, and triglycerides should be monitored at baseline and every 12 weeks. ApoB is increasingly recommended as a more accurate marker of cardiovascular risk compared to standard LDL measurement.

### Liver Function

ALT and AST should be checked at baseline and periodically. As tirzepatide promotes fat loss, hepatic fat content may change. GGT can provide additional insight into liver health.

### Thyroid Markers

TSH and free T4 should be monitored periodically. GLP-1 receptor agonists carry a boxed warning regarding medullary thyroid carcinoma observed in rodent studies.

Recommended Testing Schedule

Baseline panel before the first dose. Follow-up at 8-12 weeks after reaching a stable dose. Quarterly monitoring ongoing to track trends across multiple draws.

What Optimal Ranges Look Like

While a standard lab reference range for fasting glucose might extend to 99 mg/dL, many optimization-focused practitioners target 75-85 mg/dL. Similarly, an HbA1c below 5.0 percent may be targeted rather than simply below 5.7 percent. ApoB below 80 mg/dL is increasingly discussed in cardiovascular risk literature.

Using MyProtocolStack to Track Results

Upload your lab results directly to MyProtocolStack and let StackAI analyze your panel in context of your tirzepatide protocol. Track trends across multiple draws to see exactly how your biomarkers respond to dose changes over time.

Frequently Asked Questions

How soon should I get blood work after starting tirzepatide? Most practitioners recommend a baseline panel before starting and a follow-up at 8-12 weeks after reaching a stable dose.

What is the most important single marker to track? HbA1c provides the best single snapshot of metabolic response over a 90-day window.

Should I fast before blood work on tirzepatide? Yes, a 12-hour fast is recommended for accurate fasting glucose, insulin, and lipid measurements.

*Written by the MyProtocolStack team. Last updated: February 2026.*