What GLP-1 labels say is worth tracking

Most people on a GLP-1 medicine end up tracking something. Weight, usually. Sometimes steps, protein, or a note about which side of the abdomen got last week's shot. It is worth asking what the prescribing labels and the registration trials actually treated as worth recording, because that list is different from the one a weight graph suggests. The US labels for semaglutide and tirzepatide name specific things a clinician is expected to monitor^[1].

What the labels tell clinicians to monitor

Start with kidney function. The Wegovy label instructs prescribers to "monitor renal function in patients reporting adverse reactions that could lead to volume depletion, especially during dosage initiation and escalation", and notes that most reported cases of acute kidney injury occurred in people whose nausea, vomiting or diarrhoea had caused dehydration^[1]. The tirzepatide label carries the same instruction^[2]. That is the clinical reason a log of gut symptoms and fluid intake is more than a diary entry: it is the input that tells a prescriber whether a dose escalation went badly.

Blood glucose is next, and it is conditional. Both labels tell prescribers to check glucose before and during treatment in people who already have diabetes, and to consider lowering the dose of any insulin or sulfonylurea taken alongside, because the combination raises hypoglycaemia risk^[1]. If you do not have diabetes and take no glucose-lowering drug, the labels do not ask for routine glucose monitoring.

Then there is resting heart rate, which almost nobody logs. The semaglutide label asks for heart rate to be measured "at regular intervals consistent with usual clinical practice" and says to discontinue if a patient has a sustained increase^[1]. A wearable already collects this. Very few people think to bring it to an appointment.

Symptoms that are not routine data points

Some things belong in a note rather than a chart. The labels describe acute pancreatitis as presenting with "persistent or severe abdominal pain (sometimes radiating to the back)", with or without nausea and vomiting, and tell clinicians to watch for it^[1]. Gallstone disease is the other one: both labels say that if cholelithiasis or cholecystitis is suspected, gallbladder imaging and follow-up are indicated^[2]. Anyone with a history of diabetic retinopathy is meant to be monitored for progression, because rapid improvement in glucose control can temporarily worsen it^[1].

One item that catches people out has nothing to do with symptoms. Because tirzepatide delays gastric emptying (see the tirzepatide page for the mechanism), its label advises anyone on oral hormonal contraception to switch to a non-oral method, or add a barrier method, for four weeks after starting and for four weeks after each dose increase^[2]. That is a calendar entry tied to escalation dates, which is exactly the kind of thing a dose log is good at and a weight graph is not.

What the trials measured, and what the weight number hides

The registration trials tracked body weight as the primary endpoint. STEP 1 reported a mean reduction of 14.9% at 68 weeks on semaglutide 2.4 mg against 2.4% on placebo^[3], and SURMOUNT-1 reported 15.0% to 20.9% at 72 weeks across the tirzepatide dose groups^[4]. Those are the headline numbers, and they are the ones people replicate at home with a scale.

The body composition substudies say something the scale cannot. In the SURMOUNT-1 DXA substudy, participants on tirzepatide lost 21.3% of body weight, 33.9% of fat mass and 10.9% of lean mass by week 72. Roughly 75% of the weight lost was fat and 25% was lean tissue, and that split was about the same in the placebo group^[5]. A scale reading collapses those two into one line. It is the reason protein intake and resistance training show up in most self-tracking setups, even though neither label prescribes a target.

The parts of injection technique worth logging

Both labels give the same one-line instruction: "rotate injection sites with each dose"^[1][2]. Neither specifies a rotation pattern or a minimum gap, so any record that stops you using the same spot twice in a row satisfies the instruction. The other useful entry is the dose escalation date, since the labels tie several cautions (renal monitoring, contraceptive timing) specifically to initiation and escalation rather than to steady state.

What tracking will not answer

None of this substitutes for the tests a clinician orders. Renal function, glucose and gallbladder imaging are lab and imaging findings, not app fields. Tracking gives a prescriber better raw material for those decisions, which is a smaller claim than the one most tracking tools make for themselves. We also do not have trial evidence that structured self-tracking changes outcomes on a GLP-1 specifically. The labels describe monitoring by clinicians; they say nothing about patient logging.

If you are considering how to set this up, the defensible version is short. Log what the label ties to a clinical decision, log the escalation dates, and take the record to your prescriber. The country-by-country picture of who can prescribe these drugs at all sits on our semaglutide regulation section.