Why this panel
GLP-1 receptor agonists (semaglutide, tirzepatide, retatrutide, the older liraglutide) do three things at once: improve glycemic control, drive significant weight loss, and shift lipid profile. They also have downstream effects worth tracking — thyroid (rare risk of C-cell tumors in animal studies, the basis of the boxed warning), pancreas (acute pancreatitis is the rare serious adverse event), and gallbladder (rapid weight loss raises gallstone risk).
The panel below is the focused subset for GLP-1 monitoring. It assumes you’re running one of these agonists for weight management, glycemic control, or both. If you’re also on TRT or running a HPG-axis-touching peptide, see the TRT hormone panel guide for the sex-hormone half.
Glycemic control
Three-month average glucose exposure. The headline marker for whether the GLP-1 is doing its job. On semaglutide, HbA1c typically drops 1.0–1.8 percentage points over 6 months in T2DM patients; on tirzepatide, 1.5–2.5 points. If yours hasn't moved meaningfully by month 6 on a clinical dose, the protocol isn't working — talk to your clinician.
Fasting glucose
Snapshot of glucose at the moment of the draw. Noisy — depends on prior 24h of food, sleep, stress. HbA1c smooths through that noise and is the more stable reading. Pair them: a fasting glucose of 105 with HbA1c of 5.3 is probably a one-off; a fasting glucose of 105 with HbA1c of 6.0 is real glucose drift.
Fasting insulin
The marker most under-ordered relative to its value. Tells you whether your pancreas is working hard to keep your glucose where it is. High fasting insulin with normal fasting glucose is the early-insulin-resistance signal that HbA1c misses for years. GLP-1s should drop fasting insulin meaningfully as weight drops; if it doesn't, ask why.
HOMA-IR (calculated)
Insulin × glucose / 405 (US units). A back-of-envelope insulin sensitivity score from the two values above. Above 2.5 is meaningful insulin resistance regardless of what the individual numbers look like.
Lipids
GLP-1s improve lipid profile mostly via weight loss; some direct effects on hepatic VLDL secretion are documented. Expect modest improvements over 6 months as body composition shifts.
ApoB
The number-of-atherogenic-particles marker. Replacing or supplementing LDL-C in modern lipidology — particle count predicts cardiovascular risk better than cholesterol mass. Order it if your lab offers it; it costs about as much as the standard lipid panel.
LDL-C (LDL cholesterol)
The legacy marker — still on every lipid panel. Less precise than ApoB, but if ApoB isn't available, LDL-C is what you have. GLP-1s typically drop LDL-C 5-10% over 6 months in conjunction with weight loss.
HDL-C (HDL cholesterol)
The cardio-protective fraction. Tends to rise modestly on GLP-1s as weight drops. Don't chase it — extreme HDL elevations don't reduce risk and the relationship is non-linear at the high end.
Triglycerides
The metabolic-flexibility marker. Drops sharply with weight loss and dietary carbohydrate restriction. GLP-1s usually drive a meaningful triglyceride drop as a side effect of reduced visceral fat. Always draw fasted (12+ hours).
Triglyceride : HDL ratio
Calculate it yourself: TG ÷ HDL. Above 3.0 is the classic insulin-resistance signal. Often more informative than either number alone.
Liver + organ safety
The liver-enzyme marker most worth watching on GLP-1s. Significant weight loss can transiently elevate ALT as fat is mobilized through the liver — a small bump in the first few months is expected. A persistent rise (> 3× upper normal, or rising over multiple draws) is a real signal. Rule out other causes (alcohol, NAFLD progression, hepatitis) with your clinician.
AST (aspartate aminotransferase)
The other liver enzyme. AST rises with both liver and muscle stress; ALT is liver-specific. Read them together. AST > ALT in a non-drinker can suggest muscle origin (rhabdo, intense training); AST < ALT is the typical liver pattern.
Creatinine + eGFR
Kidney function. GLP-1s are renally cleared (in part); they don't typically harm kidneys but baseline eGFR matters for dose selection. Significant weight loss can also drop creatinine simply because muscle mass drops with fat — watch the trend, not a single number.
Worth ordering once, even if not routine
- Lipase — pancreatic enzyme. Routine ordering on GLP-1s isn’t recommended (false-positive rate is high), but if you have new persistent abdominal pain, get it checked. Acute pancreatitis is rare but serious; lipase elevation > 3× upper normal alongside symptoms is the signal.
- Calcitonin — pre-GLP-1 baseline if you have a personal or family history of medullary thyroid cancer or MEN-2. Otherwise not routinely needed; the boxed warning derives from rodent studies that haven’t translated to a human signal at population scale.
- Vitamin levels (D, B12, iron) — not GLP-1-specific, but anyone on a calorie-restricted regimen should monitor. Reduced food intake from appetite suppression makes deficiency more likely.
When to draw
- Fasted, morning, 12+ hours. All of these benefit from fasted draws — triglycerides especially, but glucose / insulin / HOMA-IR are meaningless non-fasted.
- Hold the GLP-1 dose schedule before the draw. Most clinicians don’t want you skipping a weekly dose; just draw on a normal-schedule day. The long half-life of these drugs means a single skipped day doesn’t shift readings meaningfully.
- Wait 12 weeks after a dose change for steady state. HbA1c reflects the prior 2-3 months of glucose, so an HbA1c drawn 4 weeks after a dose escalation still mostly reflects the prior dose.
How often to retest
- Starting GLP-1: baseline panel before first dose, then 3 months in, then every 6 months for the first year.
- Stable on GLP-1: every 6-12 months, depending on whether you’re still losing weight or maintaining.
- If symptoms change: abdominal pain → draw lipase + ALT/AST same week. Persistent fatigue → full panel + thyroid + iron studies.
What Juno can do with these values
Paste any of these readings into /account/labs and the lab-anomaly analyst surfaces plausible contributors — including which peptides in your active stack are documented to affect that marker. It does not diagnose; it shows what’s worth discussing with your clinician, with citations.
For HbA1c specifically, the analyst already knows about semaglutide, tirzepatide, retatrutide, cagrilintide, MOTS-c, and 5-amino-1MQ. For ALT, it knows about MK-677 (oral, hepatic processing), 5-amino-1MQ (NNMT inhibitor active in liver), glutathione, thymosin-alpha-1, and NAD+. The peptide-relevance editorial on each biomarker page lays out the mechanism — the analyst pulls the same data plus your active stack to suggest which contributors are plausible for you.