Polyethylene glycol loxenatide (PEX168) is a novel glucagon-like peptide-1 receptor agonist with a longer half-life developed by modifying the chemical structure of exenatide. This study aims to assess the efficacy and safety of PEX168 and determine the best dose. We searched PubMed, Scopus, Cochrane Library, and Web of Science databases from inception to April 25, 2023, for randomized controlled trials (RCTs) comparing PEX168 therapy alone or in combination with metformin versus other therapies. We used the risk ratio (RR) for dichotomous outcomes and the mean difference (MD) for continuous outcomes, both with 95% confidence intervals (CI). Six RCTs, including 1248 participants, were included. PEX168 added to metformin was significantly better than metformin alone regarding fasting blood glucose (MD = -1.20, 95% CI (-1.78, - 0.62), p < 0.0001), HbA1c (MD = -1.01, 95% CI (-1.48, - 0.53), p < 0.0001), and postprandial glycemia (MD = -1.94, 95% CI (-2.99, - 0.90), p = 0.0003). Similarly, for glycemic control, PEX168 monotherapy was superior to placebo (P < 0.05). No significant effects were noticed in terms of triglycerides, low-density lipoprotein, or high-density lipoprotein (p > 0.05). Body weight was significantly reduced in obese diabetic patients receiving PEX168 compared to the control group (MD = -5.46, 95% CI (-7.90, - 3.01), p < 0.0001) but not in non-obese patients (MD = 0.06, 95% CI (-0.47, 0.59), p = 0.83). People who received PEX168 alone or with metformin showed more common gastrointestinal adverse effects, especially nausea and vomiting (p < 0.05). PEX168 100, 200, and 300 ug monotherapy demonstrated comparable safety and diabetes control to metformin, but when combined with metformin, PEX168 100 and 200 ug showed significant effects on diabetes control; however, only the latter showed a significantly higher incidence of nausea and vomiting (p < 0.05). PEX168 could be a viable option for treating diabetic patients whose metformin control is inadequate or who cannot tolerate metformin. PEX168 at 100 ug in combination with metformin was found to be safe and more effective compared to metformin; however, due to the small number of trials included, these findings should be interpreted with caution, and additional trials are required.