Mounjaro vs Trulicity: Glycemic Control and Switching Evidence

Mounjaro (tirzepatide) and Trulicity (dulaglutide) are once-weekly type 2 diabetes drugs from Eli Lilly. Trulicity is a pure GLP-1 receptor agonist; Mounjaro is a dual GIP plus GLP-1 receptor agonist. There is no direct head-to-head randomized trial, but the SURPASS-2 anchor^[1] and the AWARD-11 dulaglutide dose-finding trial^[7] let us cross-walk through the Karagiannis 2024 network meta-analysis^[8]. At max doses, tirzepatide produces roughly 0.5 percentage points larger A1C reduction and 6 to 7 kg more weight loss. Trulicity has a positive CV outcomes trial (REWIND^[6]) and an on-label MACE-reduction indication; Mounjaro does not yet, although SURPASS-4 showed no CV safety signal^[4]. Trulicity is broadly on formulary with limited step therapy; Mounjaro typically requires prior authorization. SURPASS-CVOT (tirzepatide vs dulaglutide head-to-head, ~13,000 participants) is the outstanding trial.

The honest summary

• Tirzepatide drops A1C ~0.5 pp more than dulaglutide. SURPASS-2 tirzepatide 15 mg: -2.30 pp at 40 weeks^[1]. AWARD-11 dulaglutide 4.5 mg: -1.77 pp at 36 weeks^[7]. Karagiannis 2024 meta-analysis confirms the gap^[8].
• Weight loss differential is large. Tirzepatide 15 mg: -11.2 kg in SURPASS-2. Dulaglutide 4.5 mg: -4.6 kg in AWARD-11. The 6 to 7 kg gap is the biggest practical difference.
• Trulicity has REWIND. 12% relative MACE reduction over 5.4 years in T2D adults with established CVD or multiple CV risk factors^[6].
• Insurance favors Trulicity for T2D first-line. Mounjaro typically requires PA; some plans demand prior Trulicity failure.
• Switch protocol: no washout. First Mounjaro dose 2.5 mg on the next scheduled weekly day, regardless of prior Trulicity dose.

What each drug is

Trulicity (dulaglutide) was FDA-approved in September 2014. It is an Fc-fusion biologic with a ~5-day half-life. Doses: 0.75 mg (starting), 1.5 mg, 3.0 mg, and 4.5 mg (the AWARD-11 additions). FDA-approved for T2D glycemic control and for MACE reduction in adults with T2D and established CVD or multiple CV risk factors (the REWIND population). Regulated under the BLA pathway; no biosimilar has been FDA-approved.

Mounjaro (tirzepatide) was FDA-approved in May 2022. A synthetic 39-amino-acid peptide that activates both the GIP and GLP-1 receptors. Doses: 2.5 mg (starting, not for chronic use), 5, 7.5, 10, 12.5, and 15 mg. FDA-approved for T2D glycemic control. Tirzepatide is also marketed as Zepbound for chronic weight management at the same doses.

Glycemic control: indirect head-to-head

No randomized trial has directly compared the two. The anchored indirect comparison runs through SURPASS-2 (tirzepatide vs semaglutide 1 mg in metformin-treated T2D) and AWARD-11 (dulaglutide 4.5 vs 1.5 mg, same population), formalized in the Karagiannis 2024 network meta-analysis^[8].

SURPASS-2 (40 weeks, baseline A1C 8.28%): tirzepatide 5 / 10 / 15 mg dropped A1C 2.01 / 2.24 / 2.30 pp; semaglutide 1 mg dropped 1.86 pp. 86% of tirzepatide 15 mg patients reached A1C below 7.0%^[1].

AWARD-11 (36 weeks, baseline A1C 8.6%): dulaglutide 1.5 / 3.0 / 4.5 mg dropped 1.53 / 1.71 / 1.77 pp. The 4.5 mg vs 1.5 mg treatment difference was 0.24 pp^[7].

How the A1C reductions stack up

Weight loss: the bigger gap

The weight-loss differential is the headline practical difference. SURPASS-2 tirzepatide 5 / 10 / 15 mg produced -7.6 / -9.3 / -11.2 kg at 40 weeks; semaglutide 1 mg produced -5.7 kg^[1]. AWARD-11 dulaglutide 1.5 / 3.0 / 4.5 mg produced -3.0 / -4.0 / -4.6 kg at 36 weeks^[7]. At maximum doses, tirzepatide produces roughly 2.5 times the weight loss of dulaglutide. For a T2D patient with BMI in the obese range, this gap alone is large enough to make Mounjaro the evidence-favored choice on metabolic grounds; for a normal-weight T2D patient whose only goal is A1C, the prior-authorization burden may not be worth it.

Cardiovascular outcomes

REWIND (Trulicity). Gerstein 2019 Lancet randomized 9,901 adults with T2D and either established CVD (31%) or multiple CV risk factors (69%) to dulaglutide 1.5 mg or placebo for a median 5.4 years. The three-point MACE composite occurred in 12.0% on dulaglutide vs 13.4% on placebo (hazard ratio 0.88, 95% CI 0.79 to 0.99, p=0.026), a 12% relative reduction that supported the FDA-approved MACE-reduction indication^[6].

SURPASS-4 (Mounjaro, high CV risk). Del Prato 2021 Lancet randomized 2,002 adults with T2D and high CV risk to tirzepatide or insulin glargine. The MACE-4 safety analysis showed no excess CV events (HR 0.74, 95% CI 0.51 to 1.08). The trial was not powered for MACE superiority and does not support a label addition, but confirms no safety signal^[4].

SURPASS-CVOT (ongoing). Tirzepatide vs dulaglutide head-to-head for MACE in ~13,000 adults with T2D and established CVD, projected readout 2026. Until then, Trulicity is the only one of the two with a positive, adequately powered CV outcomes trial. For class context, the EXSCEL exenatide CV trial^[10] was modestly positive and the GLP-1 class is generally accepted as cardioprotective in established CVD.

Switching from Trulicity to Mounjaro: dose mapping

The Mounjaro label does not specify a switching protocol from dulaglutide, but the pharmacokinetics make the practical approach straightforward. There is no washout: the first Mounjaro injection replaces the next scheduled Trulicity injection on the same weekly day.

• From any Trulicity dose, start Mounjaro at 2.5 mg. The 2.5 mg starting dose is required by the label regardless of prior GLP-1 exposure. Titrate to 5 mg after 4 weeks if tolerated, then by 2.5 mg increments at intervals of 4 weeks or longer.
• Same day of the week. Keep the existing weekly schedule. Either drug allows a one-day window without a make-up dose.
• Expect GI side effects to return. Tolerance to dulaglutide does not fully transfer to tirzepatide; nausea, decreased appetite, and constipation often re-emerge during titration. Karagiannis 2022 documents tirzepatide nausea rates of approximately 12 to 21% at higher doses^[9].
• Run the PA in parallel. Initiate prior authorization paperwork before the patient runs out of Trulicity to avoid a coverage gap.

Insurance and formulary landscape

Trulicity has been on the US market for 11 years and is broadly on formulary across commercial, Medicare Part D, and Medicaid plans, typically with no step therapy beyond a metformin trial. Cash price is roughly $886 per month at standard wholesale.

Mounjaro's formulary footprint is narrower. Commercial plans typically require prior authorization documenting a metformin trial and often a sulfonylurea or DPP-4 inhibitor trial; some plans require failure or intolerance of a less expensive GLP-1 (commonly Trulicity or Ozempic) before approving Mounjaro. Medicare Part D coverage is plan-specific. Cash price is approximately $1,080 per month at the LillyDirect self-pay vial channel for 2.5 and 5 mg doses, with higher prices for higher doses through traditional pharmacy. Manufacturer savings cards are available for commercial insurance only, not Medicare or Medicaid.

Which patient gets which drug

• T2D + established CVD. Trulicity has the on-label MACE-reduction indication. Until SURPASS-CVOT, it is the evidence-favored choice for CV protection.
• T2D + obesity. Tirzepatide produces substantially more weight loss and modestly better A1C control. Mounjaro is evidence-favored if coverage can be navigated.
• T2D, uncontrolled on max dulaglutide. Switching to tirzepatide is the evidence-supported intensification; the indirect comparison predicts an additional 0.5 to 0.8 pp A1C drop at max dose.

What this article does not say

• Mounjaro is not the brand for weight loss in patients without diabetes — that is Zepbound, the same active ingredient at the same doses.
• Until SURPASS-CVOT reads out, the on-label MACE-reduction claim belongs to Trulicity alone among these two.
• This is not a substitute for individual prescriber judgment. Patient-specific factors can shift the optimal choice in either direction.

Bottom line

• Tirzepatide drops A1C ~0.5 pp more than dulaglutide at max doses by indirect comparison; the 6 to 7 kg weight-loss gap is larger and more clinically meaningful.
• Trulicity has REWIND and an on-label MACE indication. Mounjaro does not yet; SURPASS-4 showed no CV safety signal.
• Trulicity has broader formulary coverage. Mounjaro typically requires PA, sometimes prior Trulicity failure.
• Switching requires no washout: Mounjaro 2.5 mg on the next scheduled weekly day, then 4-week titration steps.

Related research and tools

• Trulicity (dulaglutide) for weight loss — the off-label weight-loss evidence and the BLA biosimilar landscape
• Mounjaro alternatives for type 2 diabetes — if PA navigation fails, the next-best evidence-anchored options
• Mounjaro vs Ozempic SURPASS-2 — the only direct head-to-head tirzepatide trial in T2D
• Tirzepatide overview — the Zepbound / Mounjaro drug-class page
• Trulicity overview — the dulaglutide drug-class page