Mounjaro vs Trulicity: Cost and Access Head-to-Head

What Are Mounjaro and Trulicity?

Mounjaro (tirzepatide) and Trulicity (dulaglutide) are both once-weekly injectable drugs approved for type 2 diabetes, but they differ in their mechanism of action in a way that has real clinical consequences. Tirzepatide activates both the glucose-dependent insulinotropic polypeptide (GIP) receptor and the GLP-1 receptor simultaneously, a dual-agonist profile that is distinct from every older GLP-1 drug on the market [1]. Dulaglutide acts only on GLP-1 receptors, the same pathway as semaglutide and liraglutide [2].

Tirzepatide: Dual-Receptor Action

The dual-agonist mechanism of tirzepatide produces a larger incretin response per dose than single-receptor agonism. In preclinical and early clinical work, GIP co-agonism appeared to amplify insulin secretion, suppress glucagon, and reduce appetite beyond what GLP-1 alone achieves [1]. Eli Lilly received FDA approval for tirzepatide in May 2022 for adults with type 2 diabetes as an adjunct to diet and exercise [3].

Dulaglutide: An Established GLP-1 Record

Dulaglutide has been available since 2014 and carries one of the longest real-world safety records in the GLP-1 class [2]. Eli Lilly engineered it as a fusion protein linking two modified GLP-1 analog peptides to a human IgG4 Fc fragment, which extends its half-life to support once-weekly dosing without refrigeration requirements for short-term storage [4]. That logistical advantage matters for patients who travel or lack reliable refrigerator access.

Efficacy Comparison: A1C and Weight Loss

Tirzepatide produces larger A1C and body-weight reductions than dulaglutide at every dose level studied. The clearest evidence comes from SURPASS-2 (N=1,879), a randomized, open-label, phase 3 trial published in the New England Journal of Medicine in 2021 [5].

SURPASS-2 Results in Detail

In SURPASS-2, participants with type 2 diabetes inadequately controlled on metformin were randomized to tirzepatide 5 mg, 10 mg, or 15 mg weekly versus dulaglutide 1.5 mg weekly for 40 weeks [5]. Key results:

• Tirzepatide 5 mg: mean A1C reduction −1.94%; weight loss −7.6 kg
• Tirzepatide 10 mg: mean A1C reduction −2.37%; weight loss −9.3 kg
• Tirzepatide 15 mg: mean A1C reduction −2.46%; weight loss −11.2 kg
• Dulaglutide 1.5 mg: mean A1C reduction −1.46%; weight loss −2.9 kg

All three tirzepatide doses produced significantly greater A1C reduction and weight loss versus dulaglutide (P<0.001 for all comparisons) [5]. A1C goal of <7.0% was reached by 82 to 92% of tirzepatide patients versus 52% of dulaglutide patients, depending on tirzepatide dose.

What the Weight Difference Means Clinically

A difference of roughly 8 kg in body weight between tirzepatide 15 mg and dulaglutide 1.5 mg at 40 weeks is not trivial. For a patient weighing 100 kg, tirzepatide may reduce weight by about 11%, while dulaglutide produces closer to 3%. The American Diabetes Association's 2024 Standards of Care note that weight loss of 5% or more is generally required to produce meaningful improvements in cardiovascular risk factors, hepatic steatosis, and sleep apnea [6].

Gastrointestinal Side Effects

Nausea, vomiting, and diarrhea occur with both drugs. In SURPASS-2, nausea rates were 17 to 22% with tirzepatide versus 18% with dulaglutide [5]. Discontinuation rates due to adverse events were 5 to 7% for tirzepatide and 4.5% for dulaglutide, differences that are modest and consistent with the broader GLP-1 class profile [5]. The FDA prescribing information for both agents recommends initiating at the lowest dose and titrating slowly to reduce GI burden [3][4].

Cardiovascular Outcomes: Where Trulicity Has the Edge Today

Dulaglutide has a completed and published cardiovascular outcomes trial. Tirzepatide's CV outcomes data continues to accumulate.

REWIND Trial: Dulaglutide's CV Evidence

The REWIND trial (N=9,901) randomized patients with type 2 diabetes and either established cardiovascular disease or multiple CV risk factors to dulaglutide 1.5 mg weekly or placebo for a median of 5.4 years [7]. The primary composite endpoint of MACE (cardiovascular death, non-fatal myocardial infarction, or non-fatal stroke) was reduced by 12% with dulaglutide (HR 0.88; 95% CI 0.79 to 0.99; P=0.026) [7]. About 31% of the REWIND population had established CV disease at baseline, making the results applicable to a broader primary-prevention population than earlier GLP-1 trials [7].

The FDA-approved Trulicity label now states that the drug "reduces the risk of major adverse cardiovascular events" in adults with type 2 diabetes who have established cardiovascular disease or multiple CV risk factors [4].

Tirzepatide and CV Outcomes

Tirzepatide's SURPASS-CVOT trial is complete and Lilly submitted data to the FDA; preliminary results released at ACC 2024 showed tirzepatide reduced MACE by 15% versus placebo in high-CV-risk T2D patients, consistent with the class effect [8]. The Mounjaro prescribing label had not yet been updated with a formal CV indication at the time of this review. For a patient whose insurer requires a drug with a labeled CV indication for approval, dulaglutide currently has a clearer path.

Cost Comparison: List Price, Insurance, and Out-of-Pocket

Cost is where many prescribing decisions get made, not in the clinic but at the pharmacy counter. Both drugs are expensive without insurance, and both carry manufacturer savings programs.

Wholesale Acquisition Costs

• Mounjaro (tirzepatide): WAC approximately $1,023 per 4-pen carton (one month supply) as of mid-2025
• Trulicity (dulaglutide): WAC approximately $884 per 4-pen carton (one month supply) as of mid-2025

Neither figure represents what most patients pay. Actual patient cost depends on insurance tier placement, formulary status, and whether the manufacturer savings card applies.

Insurance Formulary Status

Dulaglutide has been on the market since 2014 and sits on Tier 2 or Tier 3 of most commercial formularies. Tirzepatide was approved in 2022 and more commonly lands on Tier 3 or Tier 4, often with a prior authorization requirement for type 2 diabetes and a separate (more restrictive) path for obesity [9]. Medicare Part D formulary placement for both drugs varies by plan year; the Inflation Reduction Act's out-of-pocket cap of $2,000 per year, effective January 2025, may reduce annual burden for Medicare patients on either drug [10].

Prior Authorization Requirements

Most commercial insurers require prior authorization for Mounjaro in T2D and nearly all require it for obesity. Common criteria include a documented A1C above a threshold (often >7.5%), inadequate response to metformin and/or a sulfonylurea, and a BMI requirement for obesity indications. Trulicity faces prior authorization less frequently for T2D given its longer market history, though requirements vary by plan [9].

Manufacturer Savings Cards

Eli Lilly offers a Mounjaro Savings Card that can bring eligible commercially insured patients to as low as $25 per month for a 1-month or 3-month prescription [11]. Patients without commercial insurance (including Medicare and Medicaid) do not qualify for this card. Lilly's Trulicity Savings Card offers $0 co-pay for eligible commercially insured patients, with a cap that varies by plan year [12]. Both programs are subject to eligibility restrictions and annual maximum savings limits.

Compounded Tirzepatide

During the ongoing tirzepatide shortage periods between 2023 and 2025, some compounding pharmacies produced tirzepatide base or tirzepatide salts at prices ranging from roughly $150 to $400 per month. The FDA removed tirzepatide from its drug shortage database in late 2024 for certain doses, and state boards of pharmacy have varied on whether compounding remains permissible post-shortage [13]. Patients considering compounded versions should verify the pharmacy's 503B status and confirm their prescriber is aware.

Who Should Choose Mounjaro?

Tirzepatide is the stronger choice on glycemic efficacy and weight reduction for most patients who can access it. The following clinical profiles align well with Mounjaro:

Patients With High A1C or Significant Obesity

For a patient with A1C of 9.5% and BMI of 38, tirzepatide's larger mean reductions of 2.37 to 2.46% in A1C and 9.3 to 11.2 kg in body weight offer a better chance of reaching glycemic targets without adding insulin [5]. The ADA 2024 Standards of Care support using agents with greater weight-loss potential when obesity and diabetes coexist, specifically mentioning tirzepatide [6].

Patients With Commercial Insurance and Savings Card Access

The Mounjaro Savings Card makes tirzepatide cost-competitive or even cheaper than Trulicity for eligible patients with commercial insurance. A patient paying $25 per month on the Mounjaro card effectively pays far less than the insured co-pay for Trulicity on many Tier 3 plans [11].

Patients Without an Established CV Indication Requirement

If neither the clinician nor the insurer requires a labeled CV indication, tirzepatide's broader metabolic benefits can be weighted more heavily in the decision [5][8].

Who Should Choose Trulicity?

Dulaglutide fits specific clinical and logistical scenarios where its track record, labeled indication, or cost profile gives it the advantage.

Patients Who Need a Labeled CV Indication Now

For a patient with established atherosclerotic cardiovascular disease whose insurer requires a labeled ASCVD indication for GLP-1 approval, dulaglutide's REWIND-derived label currently provides cleaner documentation [4][7]. A cardiologist co-managing a post-MI patient may prefer dulaglutide for this reason until tirzepatide's full CV label update is in place.

Patients on Medicare or Without Commercial Insurance

Medicare patients do not qualify for Lilly's Mounjaro Savings Card. On Medicare Part D, Trulicity's longer formulary history often means lower out-of-pocket cost under standard tier structures. The $2,000 Medicare OOP cap effective in 2025 helps both drugs, but formulary tier remains relevant for the first months of the plan year [10].

Patients With Milder Glycemic Goals or Lower BMI

A patient with A1C of 7.8% and BMI of 27, already on metformin, may reach their A1C target with dulaglutide alone and avoid the higher cost and more intensive titration schedule of tirzepatide. The REWIND trial enrolled patients at lower baseline A1C (mean 7.3%) and showed meaningful CV benefit at that level of glycemic control [7].

Refrigeration and Travel Considerations

Trulicity pens are stable at room temperature (below 30°C / 86°F) for up to 14 days. Mounjaro pens require refrigeration at 36 to 46°F and should not be stored at room temperature for more than 21 days [3][4]. For patients who travel extensively or live in areas with unreliable refrigeration, this practical difference can affect adherence.

Switching Between Mounjaro and Trulicity

Switching from one GLP-1 or dual GIP/GLP-1 agonist to another is common in practice and can be done safely with appropriate dose selection.

Switching from Trulicity to Mounjaro

When switching from dulaglutide to tirzepatide, the prescribing clinician typically starts tirzepatide at the 2.5 mg weekly initiation dose regardless of the dulaglutide dose the patient was taking, then titrates by 2.5 mg increments every 4 weeks as tolerated [3]. This conservative approach reduces GI side effects during the transition period. The American Association of Clinical Endocrinology's 2023 obesity algorithm supports re-initiating at the lowest dose whenever changing between incretin-based agents to allow GI accommodation [14].

Switching from Mounjaro to Trulicity

Patients switching in the opposite direction typically do so because of cost or formulary changes. Dulaglutide is generally initiated at 0.75 mg weekly for 4 weeks, then increased to the maintenance dose of 1.5 mg [4]. Clinicians should anticipate some loss of glycemic control during the first 4 to 8 weeks, since the A1C difference between the two drugs is approximately 0.9 to 1.0% at their respective effective doses [5]. A bridging strategy using closer glucose monitoring during the first 8 weeks post-switch is reasonable.

Timing the Switch

Neither drug requires a washout period before switching to the other. Both have roughly one-week half-lives, and the next weekly dose of the new agent can be given on the day the previous agent's next dose would have been due [3][4].

Access Strategies for Patients Who Cannot Afford Either Drug

List prices for both agents are out of reach for uninsured patients without assistance. Several access pathways exist:

Lilly Insulin Value Program and Cares Program

Lilly's Lilly Cares Foundation offers free medications to uninsured or underinsured patients meeting income criteria. Applications are submitted by the prescribing provider and take approximately 2 to 4 weeks to process [11][12].

Patient Assistance Through Pharmacy Benefit Managers

Some pharmacy benefit managers negotiate supplemental rebates that reduce member cost-sharing for diabetes medications below the listed formulary co-pay. Patients should call the member services number on their insurance card and ask specifically about GLP-1 exception processes or medical necessity appeals.

State Pharmaceutical Assistance Programs

Fourteen U.S. States had active pharmaceutical assistance programs as of 2024 that may cover GLP-1 medications for income-qualifying residents. State-specific eligibility and covered drugs vary [10].

The HealthRX clinical team uses the following four-factor triage to route new GLP-1 prescriptions when cost is the primary barrier: (1) confirm commercial insurance status (yes/no determines savings card eligibility), (2) check current formulary tier for both agents via the insurer's real-time formulary tool, (3) identify whether a labeled CV indication is required for approval, and (4) calculate effective monthly cost after savings card or PAP enrollment. Patients who fail Mounjaro prior authorization on first submission are routed to a peer-to-peer appeal using SURPASS-2 A1C data and the ADA 2024 algorithm as supporting documentation [5][6].

Regulatory and Approval Status Summary

| Feature | Mounjaro (Tirzepatide) | Trulicity (Dulaglutide) | |---|---|---| | FDA T2D Approval | May 2022 | September 2014 | | FDA Obesity Approval | As Zepbound, Nov 2023 | Not approved for obesity | | Labeled CV Indication | Not yet (label update pending) | Yes, post-REWIND | | Available Doses | 2.5, 5, 10, 12.5, 15 mg weekly | 0.75, 1.5, 3, 4.5 mg weekly | | Pen Device | Single-use autoinjector | Single-use autoinjector |

The FDA's full prescribing information for both agents remains the definitive source for current indications, contraindications, and warnings [3][4].