Combining GLP-1 and glucagon at individually ineffective doses reduced food intake by 13% and boosted energy expenditure, while GLP-1 prevented glucagon's blood sugar spike — supporting dual agonist drug development.
13%Food intake reduction when GLP-1 and glucagon were combined at subanorectic doses — when neither peptide reduced appetite on its own
What the researchers found
When GLP-1 and glucagon were each given at doses too low to reduce appetite on their own (subanorectic doses), combining them produced a significant 13% reduction in food intake compared to placebo. Additionally, GLP-1 protected against glucagon's tendency to raise blood sugar, and the combination increased resting energy expenditure by 53 kcal/day.
This demonstrates a synergistic interaction between the two peptides at low doses: neither alone was effective, but together they reduced appetite, prevented hyperglycemia, and boosted metabolic rate — providing a proof-of-concept for dual GLP-1/glucagon agonist drugs.
Why it matters
This study is one of the foundational human experiments supporting the development of dual GLP-1/glucagon agonist drugs for obesity. It showed that at carefully calibrated doses, the two peptides complement each other perfectly: GLP-1 handles the appetite reduction and blood sugar protection while glucagon adds energy expenditure boosting. This is the rationale behind drugs like survodutide and other dual agonists now in clinical development.
The numbers in context
n=13 · 13% food intake reduction on combination · 53 kcal/day increase in resting energy expenditure · 120-minute infusions · Ad libitum meal at 90 minutes · Double-blind crossover · 4 conditions (GLP-1, glucagon, combo, placebo)
How the study worked
Thirteen healthy volunteers received four separate 120-minute intravenous infusions in a double-blind, randomized crossover design: low-dose GLP-1 alone, low-dose glucagon alone, both peptides combined, or saline placebo. After 90 minutes, participants ate an ad libitum meal and caloric intake was measured. Resting energy expenditure was assessed by indirect calorimetry at baseline and during infusion. Blood glucose was monitored throughout.
Who was studied
13 healthy adult volunteers (young adults)
What this study cannot tell us
Small sample of 13 healthy volunteers — not obese or diabetic individuals who would be the target population for dual agonist therapy. The acute single-session design doesn't capture chronic treatment effects. Intravenous infusion doesn't mimic the pharmacokinetics of subcutaneous drug administration. The 53 kcal/day increase in energy expenditure is modest and may not be clinically meaningful. Only male volunteers are mentioned in the MeSH terms.
How to read the evidence
Moderate-High evidence from a well-designed double-blind, randomized crossover trial. The crossover design strengthens the study by having each participant serve as their own control. Limitations include the small sample size (n=13), acute single-session design, and use of healthy volunteers rather than the target obese population.
When this study was published
Published in 2014, this is a foundational study in the dual agonist field. Its findings have been validated by the clinical development of dual GLP-1/glucagon drugs now in phase 3 trials, making it historically important even as newer data becomes available.
The bigger picture
This 2014 study from Stephen Bloom's lab at Imperial College London was an early and influential proof-of-concept for dual GLP-1/glucagon agonism. It directly informed the development of drugs like survodutide and oxyntomodulin analogs. Interestingly, this study found synergy at low doses — contrasting with the Bagger 2015 study that found no additive effect at higher doses. The difference may relate to dosing: at subanorectic levels, the complementary mechanisms are more apparent.
Questions still open
- Does this synergistic effect at low doses persist with chronic administration over weeks or months?
- Would the same synergy be observed in obese or diabetic individuals, who may have altered GLP-1 and glucagon sensitivity?
- What is the optimal ratio of GLP-1 to glucagon receptor activation for maximizing weight loss while maintaining glucose safety?
Common questions
Why combine GLP-1 and glucagon if both reduce appetite separately?
Is this the science behind drugs like survodutide?
Read the original research
Coinfusion of low-dose GLP-1 and glucagon in man results in a reduction in food intake.
Diabetes, 63(11), 3711-20
Citation
Cegla, Jaimini; Troke, Rachel C; Jones, Ben; Tharakan, George; Kenkre, Julia; McCullough, Katherine A; Lim, Chung Thong; Parvizi, Nassim; Hussein, Mohamed; Chambers, Edward S; Minnion, James; Cuenco, Joyceline; Ghatei, Mohammad A; Meeran, Karim; Tan, Tricia M; Bloom, Stephen R. (2014). Coinfusion of low-dose GLP-1 and glucagon in man results in a reduction in food intake.. Diabetes, 63(11), 3711-20. https://doi.org/10.2337/db14-0242