Cosmos Study

Adults with Diabetes on GLP-1s Largely Maintain Their First-Year Weight Loss

August 12, 2026

Team A:Kersten Bartelt, RNJoe Deckert, PhD

Team B:Jen Passini, MDEric Barkley

Key Findings

Among adults with diabetes who lost weight during their first year on a GLP-1 medication, most maintained or extended that loss when the GLP-1 was continued into the second year. At the two-year mark, 37.7% of semaglutide patients and 47.3% of tirzepatide patients had maintained their weight loss, and another 35.4% and 38.6%, respectively, had continued to lose weight.
Regaining weight was less common. At the two-year mark, the share who had regained at least a quarter of their first-year loss reached 26.9% for semaglutide users and 14.2% for tirzepatide users.
Full return to baseline weight was reached by 4.6% of semaglutide patients and less than 2% of tirzepatide patients at two years.

Glucagon-like peptide-1 (GLP-1) medications, a class that includes semaglutide and tirzepatide, are widely used both to manage type 2 diabetes and to support weight loss.¹ Research has shown substantial first-year weight loss.²^,³ However, less is known about the weight trajectory among people who stay on a GLP-1 beyond a year, and patients with diabetes are an important group to examine separately because the metabolic factors of diabetes may make weight harder to keep off. Understanding how weight changes over a second year of treatment can help patients and clinicians set realistic long-term expectations.

We studied 38,621 U.S. adults with diabetes who started a GLP-1 medication, stayed on it continuously for at least a year, and lost at least five pounds during that first year. We then tracked their weight at monthly checkpoints from 13 to 24 months after starting treatment, measuring how much of each patient’s first-year weight loss was retained or regained, or whether it was extended with further loss. Patients were followed only while they remained on the medication; anyone with a gap of more than 60 days between prescriptions was no longer counted from that point forward.

Among adults with diabetes taking semaglutide, most maintained or extended their first-year loss. One month past the one-year mark, 70.2% had held steady and 15.9% had continued to lose, with 13.9% having regained at least a quarter of their first-year loss. Over the second year, that regain share climbed steadily to 26.9% by the two-year mark, while 37.7% remained steady and 35.4% were still losing. Nearly 5% of patients regained all of the weight they had lost. Because patients were followed only while they stayed on semaglutide, the later checkpoints describe weight trends among continuing users and are skewed toward those who tolerated and responded to treatment.

Figure 1

Weight Change During the Second Year of Semaglutide Use

Figure 1. The distribution of patients with diabetes by whether they continued to lose weight, maintained their weight loss, or regained a portion of their first-year semaglutide weight loss, at monthly checkpoints from 13 to 24 months after starting treatment.

Tirzepatide patients with diabetes maintained their first-year loss more consistently and had lower regain rates than patients prescribed semaglutide. At one month past the one-year mark, 81.0% had held steady, and only 7.3% had regained at least a quarter of their loss. By the two-year mark, 47.3% remained steady and 38.6% were still losing, while meaningful regain reached 14.2% and full return to baseline stayed low at 1.6%. This again reflects weight trends among those who remained on the medication rather than all who started it.

Figure 2

Weight Change During the Second Year of Tirzepatide Use

Figure 2. The distribution of patients with diabetes by whether they continued to lose weight, maintained their weight loss, or regained a portion of their first-year tirzepatide weight loss, at monthly checkpoints from 13 to 24 months after starting treatment.

These data come from Cosmos, a dataset created in collaboration with a community of Epic health systems representing more than 310 million patient records from 2,100 hospitals and more than 49,000 clinics from all 50 U.S. states, Canada, Lebanon, and Saudi Arabia. This study was completed by two teams that worked independently, each composed of a clinician and research scientist. The two teams came to similar conclusions. Graphics by Brian Olson.

References

Müller TD, Finan B, Bloom SR, et al. Glucagon-like peptide 1 (GLP-1). Mol Metab. 2019;30:72-130. doi:10.1016/j.molmet.2019.09.010
Wilding JPH, Batterham RL, Calanna S, et al. Once-Weekly Semaglutide in Adults with Overweight or Obesity. N Engl J Med. 2021;384(11):989-1002. doi:10.1056/NEJMoa2032183
Little D, Deckert J, Bartelt K, Ganesh M, Stamp T. Weight Change With Semaglutide. Epic Research. https://epicresearch.org/articles/diabetes-drug-helps-with-weight-loss-in-both-diabetics-and-non-diabetics. Accessed on June 26, 2026.

Data Definitions

Study period: 1/1/2022 to 5/1/2026

Study population: inclusion

Adult patients (18+) with diabetes with all of the following:

First exposure to a GLP-1 medication lasting over one year
At least one GLP-1 order or dispense with no gap >60 days between consecutive orders/dispenses during the first year (each order/fill assumed to cover 60 days)
Weight readings within 30 days of beginning the GLP-1 and within 30 days of the one-year mark
Weight loss of at least five pounds in the first year
Receives care in the United States

Study population: exclusion

Any of the following before starting the GLP-1:

Bariatric surgery
Malignancy
CKD stage 4+
CHF

Additional exclusion:

Patients who switch GLP-1 type during the first year of exposure
Patient-reported GLP-1s only (no order or dispense)

Index date: Date of first GLP-1 order or dispense meeting continuity criteria

Follow-up window: Discrete weight measurement checkpoints monthly from 13 to 24 months after the index date

Censoring

A patient is censored at a given checkpoint if any of the following apply:

More than 60 days since the last GLP-1 order or dispense
Pregnancy
Development of CHF, amputation, or CKD stage 4+

Exposure: Weight change relative to first year of GLP-1 use, by GLP-1 ingredient

Outcome: Percent of the initial weight loss retained or regained at each monthly checkpoint, calculated as: (weight at checkpoint − weight at year one) / (weight at year one − weight on index date) × 100

GLP-1 medication

Orders or dispenses for:

Semaglutide (Ozempic, Wegovy, Rybelsus)
Tirzepatide (Mounjaro, Zepbound)

Diabetes: Type 1 diabetes: ICD-10-CM E10*
Type 2 diabetes: ICD-10-CM E11*
Other specified diabetes: ICD-10-CM E08*, E09*, E13*

Bariatric surgery: CPT codes 43644, 43645, 43770, 43775, 43842, 43843, 43845, 43846, 43847, 43848

Malignancy: ICD-10-CM codes C00*–C96*

Pregnancy: ICD-10-CM codes O* or a pregnancy episode

Amputation: A procedure with ICD-10-PCS code 0Y6* or a diagnosis with ICD-10-CM Z89.41*–Z89.44*, Z89.51*, or Z89.56*

CKD stage 4+: ICD-10-CM N18.4, N18.5, N18.6

CHF: ICD-10-CM code I50*

Stratifications: GLP-1 ingredient

Model specifications: Descriptive analysis: percent of year-1 weight loss retained at monthly checkpoints from 13 to 24 months, reported overall and within each ingredient

Limitations: Patients were followed only while on the GLP-1, so later checkpoints are enriched for adherent responders (survivor bias) and reflect weight trends among continuing users, not all initiators.
Dosage changes alter the expected weight trajectory.
Patients switching directly between GLP-1 types are excluded.
Lifestyle and dietary factors influencing weight regain are not captured in EMR data.
Weight measurements vary in setting, timing, and instrumentation across encounters.