Did SUSTAIN-7 have a formal extension phase?

No. SUSTAIN-7 ended at 40 weeks with no pre-specified extension. Durability inferences come from other SUSTAIN trials and real-world data.

How long does semaglutide's A1C benefit last?

SUSTAIN-6 showed maintained A1C reductions at 104 weeks, with modest attenuation attributable to disease progression rather than drug tolerance.

Does the weight advantage of semaglutide over dulaglutide persist?

Cross-trial evidence suggests yes. Weight loss with semaglutide tends to plateau around 40 to 60 weeks and is maintained, while dulaglutide's weight effect is smaller and similarly stable.

Were there safety signals that only appeared after SUSTAIN-7 ended?

SUSTAIN-6 identified a diabetic retinopathy complication signal, and longer-term data clarified gallbladder event risk. Neither was detectable in SUSTAIN-7's 40-week window.

Does semaglutide reduce cardiovascular events better than dulaglutide?

No head-to-head cardiovascular outcome trial exists. Both drugs have positive CVOT data (SUSTAIN-6 and SELECT for semaglutide, REWIND for dulaglutide), but the trials used different populations and endpoints.

Why was SUSTAIN-7 open-label?

Open-label design was chosen because the two drugs use different delivery devices (Ozempic pen vs. Trulicity pen), making blinding logistically complex without double-dummy injection protocols.

Is semaglutide 2.0 mg better than the 1.0 mg tested in SUSTAIN-7?

SUSTAIN FORTE showed semaglutide 2.0 mg provides an additional 0.18% A1C reduction over 1.0 mg at 40 weeks. The incremental benefit is real but modest.

Should patients switch from dulaglutide to semaglutide based on SUSTAIN-7?

If glycemic targets are unmet or greater weight loss is desired, switching is reasonable. Real-world data support additional A1C and weight benefit. If a patient is well-controlled on dulaglutide, there is no obligation to switch.

Did SUSTAIN-7 include patients with cardiovascular disease?

The trial did not exclude cardiovascular disease but was not enriched for it. Roughly 15% of participants had established CVD, insufficient for cardiovascular outcome analysis.

What is the pancreatitis risk with these GLP-1 drugs?

Meta-analyses of cardiovascular outcome trials, including SUSTAIN-6 and REWIND, show no statistically significant increase in pancreatitis risk for either semaglutide or dulaglutide.

SUSTAIN-7 Extension Data and What Happened After the Trial Ended

By HealthRX Medical Team

Published May 25, 2026Updated May 25, 2026Last reviewed May 25, 2026

At a glance

| Parameter | Detail | |---|---| | N | 1,201 adults with type 2 diabetes | | Intervention | Semaglutide 0.5 mg or 1.0 mg subcutaneous once weekly | | Comparator | Dulaglutide 0.75 mg or 1.5 mg subcutaneous once weekly | | Duration | 40 weeks | | Primary endpoint | Change in HbA1c from baseline | | Key result | Semaglutide 0.5 mg reduced A1C by 1.5% vs 1.1% for dulaglutide 0.75 mg; semaglutide 1.0 mg reduced A1C by 1.8% vs 1.4% for dulaglutide 1.5 mg (p < 0.0001 for both comparisons) |

Why the 40-Week Window Left Questions Unanswered

SUSTAIN-7 was designed as a 40-week, open-label, head-to-head superiority trial. That duration is standard for regulatory glycemic endpoints but short for the questions clinicians actually care about: does the A1C advantage persist at 2 years? Does weight regain narrow the gap? Do GI side effects settle differently between drugs? And does the glycemic separation translate into fewer cardiovascular events?

The trial did not include a pre-specified extension phase. Participants completed 40 weeks and stopped. This is a meaningful limitation because GLP-1 receptor agonist effects on weight can take 6 to 12 months to plateau, and the durability of glycemic control with injectable semaglutide was still being characterized when SUSTAIN-7 published in early 2018.

What the Original Data Actually Showed

Before examining post-trial evidence, the primary results deserve a closer look than most summaries provide. SUSTAIN-7 randomized patients 1:1:1:1 across four arms, matching each semaglutide dose against the clinically corresponding dulaglutide dose.

Dose-Matched Results at Week 40

| Outcome | Semaglutide 0.5 mg | Dulaglutide 0.75 mg | Difference | Semaglutide 1.0 mg | Dulaglutide 1.5 mg | Difference | |---|---|---|---|---|---|---| | A1C change (%) | −1.5 | −1.1 | −0.40 (p < 0.0001) | −1.8 | −1.4 | −0.41 (p < 0.0001) | | Body weight change (kg) | −4.6 | −2.3 | −2.26 (p < 0.0001) | −6.5 | −3.0 | −3.55 (p < 0.0001) | | A1C <7% achieved | 68% | 52% | -- | 79% | 67% | -- | | GI AEs (nausea) | 21% | 17% | -- | 22% | 15% | -- |

The weight difference at the higher dose pairing (3.55 kg) is clinically relevant. A patient on semaglutide 1.0 mg lost roughly twice as much weight as one on dulaglutide 1.5 mg. This gap matters because weight and glycemia interact: greater weight loss contributes to better insulin sensitivity, which reinforces the A1C reduction. Whether this compounding effect would widen or stabilize over a longer observation period was unknown at trial close.

Post-Trial Evidence: The Broader SUSTAIN Program

The SUSTAIN program included 10 trials (SUSTAIN 1 through 10, plus SUSTAIN FORTE). While none directly extended SUSTAIN-7's population, several provide indirect evidence about durability.

SUSTAIN-6 ran for 104 weeks and showed semaglutide maintained A1C reductions of 0.7% to 1.0% versus placebo at 2 years, with sustained weight loss of 2.9 to 4.3 kg. The glycemic effect did attenuate modestly from peak (around week 16) to week 104, consistent with progressive beta-cell decline in type 2 diabetes rather than drug tolerance. This trial also demonstrated cardiovascular benefit, with a 26% reduction in major adverse cardiovascular events (Marso et al., NEJM 2016).

SUSTAIN-3 compared semaglutide 1.0 mg to exenatide extended-release over 56 weeks. The A1C reduction with semaglutide was −1.5% at 56 weeks, only slightly less than the −1.8% seen at 40 weeks in SUSTAIN-7 for the same dose. This suggests modest attenuation but durable glycemic control well past the SUSTAIN-7 endpoint.

Estimated Durability Trajectory Based on Cross-Trial SUSTAIN Data

| Timepoint | Estimated A1C reduction (semaglutide 1.0 mg) | Source | |---|---|---| | Week 16 (near-peak) | −1.8% to −2.0% | SUSTAIN-1, SUSTAIN-7 | | Week 40 | −1.8% | SUSTAIN-7 | | Week 56 | −1.5% | SUSTAIN-3 | | Week 104 | −0.7% to −1.0% | SUSTAIN-6 |

The attenuation from week 40 to week 104 reflects natural disease progression, not drug failure. Patients on comparator arms showed the same trajectory but from a higher A1C starting floor.

What About Dulaglutide's Long-Term Data?

Dulaglutide's durability profile is best characterized by AWARD-11 and REWIND. REWIND ran for a median 5.4 years and demonstrated a 12% reduction in MACE with dulaglutide 1.5 mg. Glycemic effects attenuated over time in REWIND as well, settling around −0.6% versus placebo by year 5.

No trial has directly compared semaglutide and dulaglutide beyond 40 weeks. The cross-program comparison is imperfect: different populations, different baselines, different background therapies. Still, the pattern is consistent. Semaglutide produces roughly 0.4% greater A1C reduction at matched timepoints, and the weight gap is maintained or widened in longer-duration studies.

Real-World Evidence After SUSTAIN-7

Several retrospective cohort studies have examined semaglutide versus dulaglutide switching patterns and outcomes in clinical practice.

A 2022 analysis of U.S. claims data found that patients switching from dulaglutide to semaglutide achieved an additional 0.3% to 0.5% A1C reduction and 2 to 3 kg additional weight loss at 6 months. Patients switching in the opposite direction (semaglutide to dulaglutide) tended to gain weight and see A1C drift upward, though this population was small and likely enriched for semaglutide intolerance.

The semaglutide prescribing information does not cite SUSTAIN-7 extension data because no formal extension exists. The label relies on SUSTAIN-1 through SUSTAIN-5, SUSTAIN-7, and SUSTAIN-FORTE for efficacy claims across the dose range.

Safety Signals That Emerged After the Trial

SUSTAIN-7's 40-week safety profile showed expected GI adverse events (nausea, vomiting, diarrhea) that were somewhat more frequent with semaglutide than dulaglutide. The question of whether this difference persists was partially answered by longer-duration data.

GI tolerability. In SUSTAIN-6 (104 weeks), nausea rates with semaglutide peaked in the first 8 to 12 weeks and declined substantially by week 20. By week 52, GI event rates were comparable to placebo. This is consistent with central adaptation to GLP-1 receptor activation and suggests the SUSTAIN-7 safety snapshot may overstate the long-term GI burden of semaglutide relative to dulaglutide.

Diabetic retinopathy. SUSTAIN-6 identified a signal for diabetic retinopathy complications (HR 1.76), attributed to rapid A1C reduction in patients with pre-existing retinopathy. This was not observed in SUSTAIN-7, likely because the trial was shorter and did not enroll for that risk specifically. The ADA Standards of Care now recommend ophthalmologic screening before initiating GLP-1 therapy in patients with proliferative or severe non-proliferative retinopathy.

Gallbladder events. Post-marketing surveillance and the SELECT trial (semaglutide 2.4 mg) identified cholelithiasis as a dose-dependent class signal. At the 1.0 mg dose used in SUSTAIN-7, absolute risk remains low (approximately 1% to 2% over 2 years), but it was not detectable in the 40-week window.

Pancreatitis. The pancreatitis signal with GLP-1 receptor agonists has been extensively studied. Neither SUSTAIN-7 nor the broader SUSTAIN program showed a statistically significant increase. A 2023 meta-analysis of all GLP-1 RA cardiovascular outcome trials reported no excess pancreatitis risk (OR 1.01 to 95% CI 0.83 to 1.24).

SELECT and the Cardiovascular Question SUSTAIN-7 Could Not Answer

The SELECT trial (Lincoff et al., NEJM 2023) enrolled 17,604 adults with established cardiovascular disease and demonstrated a 20% reduction in MACE with semaglutide 2.4 mg versus placebo over a median 39.8 months. SELECT was not a diabetes trial (patients had overweight/obesity without diabetes), but it confirmed cardiovascular benefit for semaglutide at supratherapeutic doses.

Dulaglutide's REWIND trial showed cardiovascular benefit in a broader population including primary prevention patients. The two trials are not directly comparable, but both support GLP-1 RA use for cardiovascular risk reduction, a dimension SUSTAIN-7 was never powered or designed to address.

Limitations of Available Extension Evidence

Several caveats apply when extrapolating beyond SUSTAIN-7's 40-week window:

No formal extension. All post-40-week inferences rely on cross-trial comparisons with different populations.
Open-label design. SUSTAIN-7 was open-label, introducing expectation bias. Patients and investigators knew which drug they received.
Dose evolution. Semaglutide 2.0 mg (Ozempic) became available after SUSTAIN-7 published. The trial's 1.0 mg ceiling no longer represents the maximum approved dose for diabetes, making direct clinical translation less straightforward.
Background therapy differences. SUSTAIN-7 allowed metformin as background. Real-world patients often take triple or quadruple therapy, which may modify the relative advantage.
No weight-specific endpoint. Weight was a secondary outcome in SUSTAIN-7. The trial was not designed or powered to detect clinically meaningful weight-related outcomes like waist circumference reduction or metabolic syndrome resolution.

Clinical Translation: What This Means for Prescribing

For clinicians choosing between once-weekly semaglutide and dulaglutide, SUSTAIN-7 and its surrounding evidence support these conclusions:

Semaglutide produces greater A1C and weight reduction at clinically matched doses, and this advantage appears durable based on indirect comparisons across the SUSTAIN and AWARD programs.
GI side effects are modestly higher with semaglutide initially but converge over time.
Both drugs have cardiovascular outcome trial support, though semaglutide's dataset is larger (SUSTAIN-6, SELECT, SOUL).
Cost, formulary access, and auto-injector preference (dulaglutide uses a single-use pen with a hidden needle) remain legitimate differentiators when efficacy alone does not determine the choice.

Frequently asked questions

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References

Pratley RE, Aroda VR, Lingvay I, et al. Semaglutide versus dulaglutide once weekly in patients with type 2 diabetes (SUSTAIN 7): a randomised, open-label, phase 3b trial. Lancet Diabetes Endocrinol. 2018;6(4):275-286. PubMed
Marso SP, Bain SC, Consoli A, et al. Semaglutide and cardiovascular outcomes in patients with type 2 diabetes. N Engl J Med. 2016;375(19):1834-1844. PubMed
Gerstein HC, Colhoun HM, Dagenais GR, et al. Dulaglutide and cardiovascular outcomes in type 2 diabetes (REWIND): a double-blind, randomised placebo-controlled trial. Lancet. 2019;394(10193):121-130. PubMed
Lincoff AM, Brown-Frandsen K, Colhoun HM, et al. Semaglutide and cardiovascular outcomes in obesity without diabetes. N Engl J Med. 2023;389(24):2221-2232. PubMed
U.S. Food and Drug Administration. Ozempic (semaglutide) prescribing information. FDA Label
American Diabetes Association Professional Practice Committee. Standards of Care in Diabetes, 2023. Diabetes Care. 2023;46(Suppl 1). PubMed