Clinical bottom line
Dual therapy combining GLP-1 receptor agonists (GLP-1 RAs) with insulin offers a promising approach for improving glycemic control in type 2 diabetes (T2D), potentially enhancing efficacy while mitigating insulin-related adverse effects such as weight gain and hypoglycemia. Fixed-ratio combinations of long-acting insulin and GLP-1 RAs demonstrate improved HbA1c reductions, weight loss or neutrality, and favorable safety profiles compared to insulin alone. However, patient selection and individualized titration remain critical to optimize outcomes.
What the evidence shows
Østergaard et al. (2017) reviewed fixed-ratio combination therapy of liraglutide and insulin degludec (IDegLira) in T2D, reporting superior glycemic control and weight reduction compared to basal insulin alone. The combination improved fasting and postprandial glucose with lower hypoglycemia risk, supporting its use in patients inadequately controlled on insulin or oral agents.
Vedtofte et al. (2017) further confirmed the efficacy and safety of IDegLira, highlighting its ability to reduce insulin dose requirements and improve patient adherence through simplified regimens.
Zhang et al. (2025) discuss emerging dual and triple agonists targeting GLP-1, GIP, glucagon, and GDF15 pathways, which may offer enhanced metabolic benefits beyond current GLP-1 RA and insulin combinations, though these remain investigational.
Newell et al. (2022) provide a case report illustrating successful initiation of semaglutide in a complex T2D patient post-liver transplant, demonstrating GLP-1 RA utility in challenging clinical scenarios alongside insulin therapy.
Systematic reviews (2021, 2025) on GLP-1 RAs as adjuncts to insulin in diabetes highlight consistent improvements in HbA1c, weight, and hypoglycemia profiles, although most data focus on type 2 diabetes.
Caveats and uncertainty
Most evidence derives from relatively short-term trials; long-term cardiovascular and renal outcomes with dual therapy require further study.
Variability in patient response and tolerability, particularly gastrointestinal side effects from GLP-1 RAs, may limit adherence.
Optimal timing for initiation and titration strategies of dual therapy are not fully standardized.
Emerging multi-agonist therapies are promising but currently lack robust clinical trial data for routine use.
How this may change practice
Clinicians should consider fixed-ratio GLP-1 RA and insulin combinations for patients with T2D inadequately controlled on basal insulin or oral agents, especially when weight gain or hypoglycemia risk is a concern.
Simplified dosing regimens may improve adherence and patient satisfaction.
Monitoring for gastrointestinal side effects and gradual dose titration can enhance tolerability.
Future integration of novel dual and triple agonists may further refine individualized diabetes management.
Multidisciplinary collaboration and patient education remain essential to optimize therapy outcomes.