What is GLP-1?
GLP-1 stands for glucagon-like peptide-1 — a hormone naturally produced in your gut in response to food. It plays several roles in regulating blood sugar and appetite: it stimulates insulin release, suppresses glucagon (which raises blood sugar), slows gastric emptying, and signals to your brain that you're full.
GLP-1 receptor agonists have product-specific indications, actions and doses. Use the exact current prescribing information rather than assuming the same benefits or effects for every drug or person.
The medications were originally developed for Type 2 diabetes management, where their blood sugar lowering effects were the primary goal. The dramatic weight loss observed as a side effect led to their development as dedicated weight loss medications — and to the current wave of widespread use.
How GLP-1 medications produce weight loss
Semaglutide labeling describes reduced calorie intake, likely through appetite effects, in its weight-management action. This does not measure an individual’s response or establish the same effect for every GLP-1-related drug.
Semaglutide labeling describes delayed gastric emptying. A personal glucose trace does not isolate that mechanism or establish that it explains every post-meal change.
Do not interpret a glucose trace as a measurement of insulin sensitivity, energy metabolism or fat-storage signaling. Medication effects need their own clinical evidence and individualized assessment.
Reduced glucagon secretion. GLP-1 medications suppress glucagon release from the pancreas. Since glucagon raises blood sugar by signaling the liver to release stored glucose, suppressing it produces lower overall blood glucose levels — particularly fasting glucose.
Ozempic, Wegovy, Mounjaro — what's the difference?
| Medication | Active ingredient | Approved for |
|---|---|---|
| Ozempic | Semaglutide | Type 2 diabetes |
| Wegovy | Semaglutide; formulation-specific dosing | Weight-management and other indication-specific labeling |
| Mounjaro | Tirzepatide (GLP-1 + GIP) | Type 2 diabetes |
| Zepbound | Tirzepatide; indication-specific dosing | Weight-management and other indication-specific labeling |
| Victoza/Saxenda | Liraglutide | Diabetes / weight loss |
Ozempic and Wegovy contain the same active ingredient (semaglutide) at different doses. Ozempic is approved for Type 2 diabetes; Wegovy is approved for weight loss. Many people are prescribed Ozempic off-label for weight management when Wegovy is unavailable or cost-prohibitive.
Tirzepatide acts at both GIP and GLP-1 receptors. Mounjaro and Zepbound have separate indications, not simply different dose strengths. No universal comparison across all doses and populations is established here.
What GLP-1 does to your glucose
Ozempic labeling reports lower fasting and postprandial glucose in studied adults with type 2 diabetes. These are group results, not a guarantee of flatter CGM curves or proof of the mechanism in an individual.
Semaglutide labeling reports glucose outcomes in studied populations. A lower personal sensor curve does not by itself establish improved overall metabolic health or measure insulin sensitivity.
Time in range is the proportion of readings within a defined glucose interval. Consensus recommends over 70% in 70–180 mg/dL for many nonpregnant adults with type 1 or type 2 diabetes, individualized with their care team. Time below range, time above range and variability add information that TIR alone does not supply. CGM provides dense sampling, but TIR has also been studied using seven-point fingerstick profiles; it does not replace laboratory HbA1c.
CGM can supply glucose observations for discussion with your prescriber, but a personal trace does not establish medication efficacy, dose adequacy or the cause of a change. Do not adjust or switch medication from sensor data; follow the prescribed plan.
Discuss CGM observations during treatment
CGM can supply glucose observations for discussion with your prescriber, but a personal trace does not establish medication efficacy, dose adequacy or the cause of a change. Do not adjust or switch medication from sensor data; follow the prescribed plan.
CGM shows interstitial glucose alongside logged events. Associations in one person’s trace do not prove a meal, activity, sleep or stress caused the change. Glucose alone does not measure insulin, fat burning, energy availability or overall metabolic health.
CGM can supply glucose observations for discussion with your prescriber, but a personal trace does not establish medication efficacy, dose adequacy or the cause of a change. Do not adjust or switch medication from sensor data; follow the prescribed plan.
Catch low glucose. In the Ozempic prescribing information, low blood sugar was reported more often when semaglutide was combined with insulin or a sulfonylurea. Some CGM systems can alert you to low glucose in real time, including during sleep, but not all do: the over-the-counter Dexcom Stelo does not include the high, low and urgent-low glucose alarms of Dexcom's prescription systems (FDA K234070). If low-glucose alerts matter for you, ask your prescriber which CGM suits your treatment.
Semaglutide labeling warns of increased hypoglycemia risk with insulin or sulfonylureas. Not using insulin alone does not establish that an OTC device without clinical low-glucose alarms is suitable. Discuss medication risks and device selection with your prescriber. See our device discussion guide →
Frequently asked questions
Sources & Further Reading
This article draws on the following clinical sources:
- Wilding et al. Once-Weekly Semaglutide in Adults with Overweight or Obesity (STEP 1). NEJM 2021. PubMed →
- Jastreboff et al. Tirzepatide Once Weekly for the Treatment of Obesity (SURMOUNT-1). NEJM 2022. PubMed →
- Novo Nordisk. Wegovy (semaglutide) injection, current US prescribing information. DailyMed →
- FDA. Wegovy (semaglutide) Prescribing Information. FDA.gov →