Dulaglutide vs other GLP-1 receptor agonists: differences in efficacy for HbA1c and postprandial glucose control?

Abstract

Dulaglutide demonstrates non-inferior to superior HbA1c efficacy compared to other GLP-1 receptor agonists, with the magnitude of benefit varying by comparator. Dulaglutide 1.5 mg weekly was non-inferior to liraglutide 1.8 mg daily (-1.42% vs -1.36% HbA1c reduction), though meta-analysis of six studies suggested small superiority favoring dulaglutide at 6 months (-0.17%, 95% CI -0.26 to -0.08) and 12 months (-0.22%, 95% CI -0.32 to -0.11). Against exenatide 10 μg twice daily, dulaglutide showed consistent superiority with 0.4-0.6% greater HbA1c reductions at both 26 and 52 weeks (P<0.001). Compared to semaglutide, dulaglutide 1.5 mg achieved similar glycemic control to semaglutide 0.5 mg, though semaglutide demonstrated superiority when initiated in patients already receiving stable dulaglutide therapy (-0.4% vs +0.2%, p=0.006).

Postprandial glucose control data were limited, with only two studies providing specific assessments. Dulaglutide showed greater reductions in premeal and postprandial glucose levels than exenatide at midday and evening meals, though exenatide achieved superior 2-hour postprandial glucose excursion reduction. Semaglutide reduced postprandial hyperglycemia across all meals more effectively than dulaglutide and improved multiple glucose variability metrics including standard deviation (p=0.005), mean amplitude of glycemic excursions (p=0.013), time above range (p=0.039), and time in range (p=0.031). The comparative efficacy hierarchy appears influenced by dose selection, with dulaglutide 1.5 mg consistently outperforming 0.75 mg, and by pharmacokinetic differences between rapid-acting, intermediate-acting, and long-acting GLP-1 receptor agonists.

Methods

We analyzed 10 sources from an initial pool of 200, using 6 screening criteria. Each paper was reviewed for 6 key aspects that mattered most to the research question.

Records from Elicit search

n = 200

Papers screened using: Population Age and Diabetes Type, Study Comparison, Efficacy Outcomes, Study Design, Study Duration, Drug Administration

n = 200

Papers screened out

n = 190

Papers included for extraction

n = 10

HbA1c Efficacy

Dulaglutide versus Liraglutide

Direct head-to-head comparison in the AWARD-6 trial demonstrated non-inferiority of dulaglutide 1.5 mg weekly to liraglutide 1.8 mg daily. The least-squares mean HbA1c reduction was -1.42% for dulaglutide compared to -1.36% for liraglutide, with a between-group difference of -0.06% (95% CI -0.19 to 0.07, p<0.0001 for non-inferiority). Non-inferiority was established using a 0.4% margin.

The meta-analysis by Ye et al. including three RCTs and three observational studies (N=5,817) found dulaglutide superior to liraglutide for HbA1c reduction. At 6 months, dulaglutide showed a mean difference of -0.17% (95% CI -0.26 to -0.08), and at 12 months, -0.22% (95% CI -0.32 to -0.11).

Dulaglutide versus Exenatide

Dulaglutide demonstrated superior HbA1c reduction compared to twice-daily exenatide across multiple studies. In the AWARD-1 trial (N=978), dulaglutide 1.5 mg reduced HbA1c by -1.51% versus -0.99% for exenatide 10 μg at 26 weeks, with superiority maintained at 52 weeks (-1.36% vs -0.80%, between-group difference -0.56%, P<0.001).

Dulaglutide versus Semaglutide

Three analyses from the SUSTAIN 7 trial compared semaglutide to dulaglutide. Schmidt et al. reported that at 40 weeks, HbA1c improvements were similar or favored semaglutide across baseline HbA1c subgroups (p=0.02 for interaction). More subjects with baseline HbA1c >9% achieved HbA1c targets with semaglutide versus dulaglutide.

In a post-hoc comparison of clinically available doses, Pratley et al. found similar glycemic control between semaglutide 0.5 mg and dulaglutide 1.5 mg at week 40, though semaglutide showed greater weight loss.

The prospective study by Omachi et al. demonstrated semaglutide 0.5 mg superiority over dulaglutide 0.75 mg in a population already treated with dulaglutide. After 24 weeks, the dulaglutide group showed minimal change (+0.2% ± 0.6%) while semaglutide reduced HbA1c by -0.4% ± 0.5% (p=0.006).

Postprandial Glucose Control

Postprandial glucose control data were limited across the included studies. Most trials focused on HbA1c as the primary glycemic outcome without reporting specific postprandial measurements.

Two studies provided postprandial-specific data. In the AWARD-1 trial comparing dulaglutide to exenatide, dulaglutide 1.5 mg and 0.75 mg showed greater reductions in premeal and postprandial glucose levels compared to both placebo and exenatide. However, for 2-hour postprandial glucose excursions, exenatide demonstrated a greater reduction compared to dulaglutide.

The Omachi et al. prospective study assessed glucose variability using continuous glucose monitoring. Semaglutide 0.5 mg reduced postprandial hyperglycemia across all meals more effectively than dulaglutide 0.75 mg. Multiple glucose variability metrics favored semaglutide: standard deviation (SD) improved with p=0.005, mean amplitude of glycemic excursions (MAGE) with p=0.013, coefficient of variation (%CV) with p=0.038, time above range (TAR) with p=0.039, and time in range (TIR) with p=0.031.

Synthesis

The comparative efficacy of dulaglutide versus other GLP-1 receptor agonists shows a hierarchy influenced by multiple factors including dose, comparator choice, and study population characteristics.

Dose-Response Relationships

The consistent finding that dulaglutide 1.5 mg outperforms 0.75 mg suggests a dose-dependent effect, though the increment appears to follow diminishing returns rather than linear scaling. The 0.75 mg dose achieved approximately 85% of the 1.5 mg dose’s efficacy in AWARD-1, indicating approaching therapeutic ceiling effects.