Trulicity vs Ozempic: Mechanism, Dosing, and Data

What are these two drugs?

Trulicity is the brand name for dulaglutide, a GLP-1 receptor agonist approved as a biologic in 2014 [1]. Ozempic is the brand name for semaglutide injection, approved in December 2017 [5]. Both are injected under the skin once a week and both treat adults with type 2 diabetes.

The cardiovascular indications are not identical. Trulicity is approved to reduce major adverse cardiovascular events in adults with type 2 diabetes who have established cardiovascular disease or multiple cardiovascular risk factors [1]. Ozempic's cardiovascular indication covers adults with type 2 diabetes and established cardiovascular disease [2]. Ozempic also carries a kidney indication, to reduce the risk of sustained eGFR decline, end-stage kidney disease and cardiovascular death in adults with type 2 diabetes and chronic kidney disease [2]; the Trulicity label has no kidney indication [1].

Age ranges differ too. Trulicity is approved for patients 10 years and older with type 2 diabetes, with a lower maximum dose in that group [1]. Ozempic's label states that safety and efficacy have not been established in pediatric patients [2].

How do the mechanisms compare?

Both drugs mimic the gut hormone GLP-1 and act on the same receptor. The dulaglutide label describes 90% amino acid sequence homology to endogenous GLP-1(7-37); the drug raises cAMP inside pancreatic beta cells, which triggers glucose-dependent insulin release, reduces glucagon secretion and slows gastric emptying [1]. The semaglutide label describes 94% sequence homology and activation of GLP-1 receptors, including receptors in brain areas that regulate appetite and calorie intake, plus delayed gastric emptying [2]. The semaglutide label states that the exact mechanism behind its cardiovascular risk reduction is not established [2].

Their half-lives and dose-escalation schedules differ: dulaglutide's half-life is about 5 days [1], and semaglutide's is about 1 week [2].

How do the dosing schedules compare?

Trulicity [1]

• The label recommends a starting dose of 0.75 mg once weekly, with an increase to 1.5 mg after 4 weeks for additional glycemic control if needed, then 1.5 mg steps after at least 4 weeks on the current dose.
• The maximum recommended adult dose is 4.5 mg once weekly. For children 10 and older, the label's maximum is 1.5 mg once weekly.
• For a missed dose, the label says to give it if at least 3 days (72 hours) remain before the next scheduled dose; otherwise the dose is skipped.
• The label allows any time of day, with or without food, injected into the abdomen, thigh or upper arm.

Ozempic [2]

• The label recommends 0.25 mg once weekly for 4 weeks, stating that this dose is not a maintenance dose, then 0.5 mg once weekly.
• Maintenance is 0.5, 1 or 2 mg, with each increase after at least 4 weeks on the current dose; the maximum is 2 mg weekly.
• For the kidney indication, the label specifies increasing to 1 mg after at least 4 weeks on 0.5 mg.
• For a missed dose, the label says to give it within 5 days; otherwise it is skipped.
• The label allows any time of day, with or without meals, into the same three injection sites.

Trulicity starts at 0.75 mg and reaches 4.5 mg in adults; Ozempic starts at 0.25 mg and stops at 2 mg [1][2].

What did the head-to-head trial show?

SUSTAIN 7 randomized 1,201 adults with type 2 diabetes on metformin to one of four once-weekly arms: semaglutide 0.5 mg, dulaglutide 0.75 mg, semaglutide 1 mg or dulaglutide 1.5 mg, for 40 weeks. The trial was open-label, so participants and investigators knew which drug was given [3].

At week 40, HbA1c fell 1.5 points on semaglutide 0.5 mg versus 1.1 points on dulaglutide 0.75 mg, and 1.8 versus 1.4 points for the higher-dose pair. Body weight fell 4.6 kg versus 2.3 kg, and 6.5 kg versus 3.0 kg [3].

What the trial does not cover matters. It tested dulaglutide at 0.75 and 1.5 mg, not at the 3 mg and 4.5 mg doses the adult label now allows, and it did not test semaglutide at its 2 mg maximum [1][3]. The result describes those two dose pairs, not a contest at each drug's ceiling.

How does the cardiovascular evidence compare?

REWIND enrolled 9,901 adults aged 50 and older with type 2 diabetes and either cardiovascular disease or cardiovascular risk factors; 31.5% had established cardiovascular disease. Dulaglutide 1.5 mg weekly was compared with placebo over a median of 5.4 years. The composite of non-fatal heart attack, non-fatal stroke or cardiovascular death occurred in 12.0% versus 13.4% (hazard ratio 0.88, 95% CI 0.79 to 0.99; p=0.026). All-cause death was 10.8% versus 12.0%, which was not significant [6].

For semaglutide, SUSTAIN-6 randomized 3,297 adults with type 2 diabetes, 83% of whom had established cardiovascular disease, chronic kidney disease or both, to semaglutide 0.5 or 1 mg weekly or placebo for 104 weeks. The same three-part composite occurred in 6.6% versus 8.9% (hazard ratio 0.74, 95% CI 0.58 to 0.95) [7].

SELECT used a different dose and a different population: 17,604 adults aged 45 and older with established cardiovascular disease and a BMI of 27 or higher, none with diabetes, given semaglutide 2.4 mg weekly, which is not an Ozempic dose. The composite occurred in 6.5% versus 8.0% (hazard ratio 0.80, 95% CI 0.72 to 0.90) over a mean follow-up of 39.8 months [8].

The kidney-outcome trial, FLOW, randomized 3,533 adults with type 2 diabetes and chronic kidney disease to semaglutide 1 mg weekly or placebo. The primary kidney composite occurred in 18.7% versus 23.2% (hazard ratio 0.76, 95% CI 0.66 to 0.88) [9], and it underlies Ozempic's kidney indication [2].

Because these trials enrolled different populations and used different doses, the hazard ratios are not a direct comparison of the two drugs [6][8][7].

Is either drug a weight-loss drug?

No. The Trulicity label has no obesity indication [1], and the Ozempic label has no weight-loss indication either [2]. Wegovy is a separate semaglutide product listed by FDA [4].

At the 2.4 mg dose used in that separate product, STEP 1 randomized 1,961 adults without diabetes to semaglutide 2.4 mg weekly or placebo for 68 weeks; mean weight change was -14.9% versus -2.4%, and 86.4% versus 31.5% lost at least 5% [10]. In the STEP 4 withdrawal trial, 803 adults who reached 2.4 mg after a 20-week run-in (mean loss 10.6%) were then randomized to continue or switch to placebo for 48 weeks; weight changed -7.9% versus +6.9% between week 20 and week 68 [11].

Dulaglutide has no weight-management indication [1]; SUSTAIN 7 above measured weight change at its 0.75 and 1.5 mg doses in adults with type 2 diabetes [3]. Its dose-ranging study, AWARD-11, randomized 1,842 adults on metformin to dulaglutide 1.5, 3 or 4.5 mg weekly. At the 36-week primary endpoint, HbA1c fell 1.5, 1.6 and 1.8 points, HbA1c below 7% was reached by 50%, 56% and 62%, and 4.5 mg was superior to 1.5 mg for weight loss as a secondary outcome [12].

How do the side effects compare?

Both labels carry a boxed warning on thyroid C-cell tumors in rodents, with unknown relevance in humans, and contraindication for anyone with a personal or family history of medullary thyroid carcinoma or MEN 2 [1][2].

In Trulicity's adult placebo-controlled pool (placebo N=568, 0.75 mg N=836, 1.5 mg N=834), nausea occurred in 5.3%, 12.4% and 21.1%; diarrhea in 6.7%, 8.9% and 12.6%; vomiting in 2.3%, 6.0% and 12.7%. Any gastrointestinal reaction occurred in 21%, 32% and 41%, and 0.2%, 1.3% and 3.5% stopped treatment for a GI reason [1].

In Ozempic's pooled placebo-controlled trials in type 2 diabetes (placebo N=262, 0.5 mg N=260, 1 mg N=261), nausea occurred in 6.1%, 15.8% and 20.3%; any gastrointestinal reaction in 15.3%, 32.7% and 36.4%; and 0.4%, 3.1% and 3.8% stopped for a GI reason [2].

Hypoglycemia risk rises when either drug is combined with insulin or a sulfonylurea, and both labels suggest considering a lower dose of those medicines when starting [1][2]. With insulin glargine, low glucose below 54 mg/dL occurred in 14.7% on dulaglutide 1.5 mg versus 9.3% on placebo [1].

Which does the evidence favor?

The answer depends on the question. On HbA1c and body weight at the doses tested in SUSTAIN 7, semaglutide came out ahead [3]. On cardiovascular outcomes in type 2 diabetes, both drugs have positive trials, but in different populations: REWIND included people with risk factors and no prior event, while SUSTAIN-6 required high cardiovascular risk [6][7]. On kidney outcomes, only Ozempic has a labeled indication, based on FLOW [2][9]. On pediatric type 2 diabetes, only Trulicity is approved [1][2]. Neither is approved to treat obesity [1][2].