Efficacy and safety of once-weekly basal insulin therapy in people with type 1 diabetes: A systematic review and meta-analysis

Aims: Once-weekly basal insulins may offer similar or superior HbA1c reduction compared to once-daily analogues in people with type 1 or type 2 diabetes. However, concerns about hypoglycaemia persist in individuals on multiple daily injections. This meta-analysis (PROSPERO CRD42024606874) aimed to evaluate the efficacy and safety of once-weekly basal insulin therapy in type 1 diabetes. Materials and Methods: A systematic search was conducted in MEDLINE, Web of Science and CENTRAL up to 1 April 2025. We included randomized controlled trials (RCTs) comparing insulin icodec or efsitora against once-daily basal insulins in people with type 1 diabetes. Three reviewers independently evaluated the retrieved citations. The primary outcome was the change in HbA1c. Meta-analysis was performed using fixed- or random-effects models based on heterogeneity. Results: Five RCTs were included, enrolling 1629 adults living with type 1 diabetes. Once-weekly and once-daily basal insulins had similar effects on HbA1c (high certainty), body weight (moderate certainty), time in range (moderate certainty) and time above range. However, safety concerns emerged due to increased rates of level 3 hypoglycaemia (incidence rate ratio 2.532, 95% confidence interval [CI] 1.758–3.645; moderate certainty). A significantly lower weekly bolus insulin dose was observed with once-weekly basal insulin therapy (estimated treatment ratio 0.837, 95% CI 0.794–0.882, I2 = 0%; high certainty). Conclusions: This meta-analysis is the first to evaluate the efficacy and safety of once-weekly basal insulin therapy exclusively in adults with type 1 diabetes and including all published RCTs. The analysis demonstrated a similar glucose-lowering effect compared to once-daily basal insulin but revealed an increased occurrence of severe hypoglycaemia.