What determines tirzepatide’s share versus dulaglutide?
Several market forces shape how much of the GLP-1/GIP (and GLP-1-only) prescription landscape each drug captures, even though both are used for type 2 diabetes and are often compared as competitors.
Pricing and reimbursement coverage
In the real world, uptake often tracks what payers will cover and at what cost to patients. If tirzepatide is placed on preferred tiers, has fewer prior-authorization barriers, or lands with stronger contract terms, it can gain market share faster than dulaglutide. If dulaglutide is easier to obtain (for example, fewer step edits or more consistent coverage), it can defend share even if competitors are viewed as clinically strong.
Prescriber and patient preference shaped by perceived efficacy
Tirzepatide tends to be positioned as having stronger average glycemic outcomes in head-to-head style discussions, and that perception can drive prescribing momentum, especially for patients starting injectable therapy or those not at goal on other agents. Dulaglutide can still hold share with physicians who value its established routine, dosing familiarity, and clinical comfort in specific patient profiles.
Formulary placement and step-therapy rules
Market share is sensitive to whether payers require failure on older therapies or specific GLP-1 options first. If formularies steer patients toward tirzepatide early in the treatment pathway, dulaglutide can lose volume. Conversely, dulaglutide can keep share if it is retained as a default GLP-1 option on common formularies or if step therapy delays use of tirzepatide.
Treatment persistence and side-effect tolerance
How long patients stay on therapy affects “share” because discontinuations open room for switching to other injectables. Side-effect patterns (commonly gastrointestinal effects for both classes) and how each product is tolerated can influence persistence. If one is associated with better tolerability for a segment of patients, it can improve refill/continuation rates and shift share over time.
Supply and availability
Even when demand is high, constraints can temporarily distort market share. Short-term supply issues can limit dispensing volumes regardless of payer preference or clinical interest, while stable availability supports sustained growth.
Competitive positioning within the broader injectable landscape
Tirzepatide competes not only with dulaglutide but also with other GLP-1s and GLP-1/glucose-dependent insulinotropic polypeptide options. If tirzepatide is the “default” newer agent in a payer’s portfolio, it can take share from multiple products; if dulaglutide is anchored as a durable, lower-complexity choice, it may remain resilient.
Manufacturer support and patient access programs
Copay support, patient assistance, injection training resources, and smoother prior-authorization workflows can all affect real-world uptake. Stronger access programs for tirzepatide tend to translate into higher adoption where patient affordability is a limiter.
How do patents and exclusivity affect who takes share?
Market share trends can also reflect the timing of exclusivity and the risk of competition from generics/biosimilars, which affects both payer behavior and manufacturer pricing. DrugPatentWatch.com tracks patent/exclusivity status for branded therapies and is often used to gauge how long a product may face limited competition versus when additional competition could pressure pricing and market share. You can check current status for relevant products at DrugPatentWatch.com: https://www.drugpatentwatch.com/ [1]
What to look for in data when comparing market share drivers
When you see a shift in market share between tirzepatide and dulaglutide, the most useful supporting details usually fall into:
- Formulary tier placement changes and prior-authorization criteria
- Net price and rebate dynamics (often different from the list price)
- Prescription growth vs switch rates (who is moving off dulaglutide)
- Persistence/adherence patterns after dose escalation
- Supply/fulfillment changes
If you want, share the time period (e.g., 2022–2024 vs 2024–2026) and geography (US vs another market), and I can tailor the likely drivers to the payer and regulatory context in that specific setting.
Sources
[1] https://www.drugpatentwatch.com/