Dulaglutide

Dulaglutide (Trulicity) is a once-weekly GLP-1 receptor agonist approved for type 2 diabetes and, since 2020, for cardiovascular risk reduction. It is the first GLP-1 agonist to demonstrate cardiovascular benefit in a population predominantly without prior cardiovascular disease.

The REWIND trial (N=9,901, median 5.4-year follow-up) is the landmark cardiovascular outcomes study. The primary composite outcome (nonfatal MI, nonfatal stroke, or cardiovascular death) occurred in 12.0% of dulaglutide patients versus 13.4% of placebo patients: HR 0.88 (95% CI 0.79-0.99, P=0.026). This 12% relative reduction is statistically significant and notable because only 31.5% of participants had established cardiovascular disease at baseline, meaning the benefit extended to a primary-prevention-heavy population. Nonfatal stroke was significantly reduced (HR 0.76, 95% CI 0.61-0.95). All-cause mortality trended lower but was not statistically significant (HR 0.90, 95% CI 0.80-1.01, P=0.067).

Compared to semaglutide's SELECT trial (20% MACE reduction, N=17,604), dulaglutide's REWIND showed a smaller but still significant cardiovascular benefit, and importantly in a population with less baseline cardiovascular disease. This makes dulaglutide's CVOT the most relevant to a primary-prevention context.

Weight loss is dose-dependent and modest compared to newer agents. AWARD-11 (N=1,842, 36 weeks) showed weight change of 3.1 kg (1.5 mg), 4.0 kg (3.0 mg), and 4.7 kg (4.5 mg). This is substantially less than semaglutide (14.9% in STEP 1) or tirzepatide (22.5% in SURMOUNT-1).

The body composition signal is concerning. A small study (N=21 hemodialysis patients with type 2 diabetes, 6 months) found dulaglutide significantly reduced both fat mass (21.9 to 18.9 kg, P=0.037) and skeletal muscle mass (21.0 to 20.2 kg, P=0.011). This raises concern about sarcopenia risk in vulnerable populations. This human finding conflicts with preclinical data showing dulaglutide ameliorated muscle wasting in mouse models of sarcopenia by suppressing myostatin and muscle-atrophic factors (atrogin-1, MuRF-1) while enhancing myogenic factors. The discrepancy suggests population-dependent effects on muscle.

REWIND included an exploratory cognitive outcomes analysis in its 9,901 participants, reporting possible reduction in composite cognitive impairment and renal outcomes, though detailed body-composition data were not part of that analysis.

Safety is consistent with the GLP-1 class. Gastrointestinal adverse events (nausea 14.2-17.3%, diarrhea 7.7-12.0%, vomiting 6.4-10.1%) are dose-related and most common early in treatment. Adjudicated pancreatitis rate was 1.4 cases per 1,000 patient-years with dulaglutide versus 0.88 with non-incretin comparators. REWIND showed significantly more GI adverse events with dulaglutide versus placebo (47.4% versus 34.1%, P<0.0001). No pancreatic cancer, C-cell hyperplasia, or medullary thyroid carcinoma was reported in AWARD-11.