GLP-1 Intravenous Infusion Study
Objective: To examine the effect of intravenously infused glucagon-like peptide 1 (GLP-1) on subjective appetite sensations and spontaneous energy intake in humans
Protocol Steps
Study design setup
Conduct a placebo-controlled, randomized, blinded, crossover study with 20 young, healthy, normal-weight men
Note: Study is randomized, blinded, and uses a crossover design
View evidence from paper
“20 young, healthy, normal-weight men participated in a placebo-controlled, randomized, blinded, crossover study”
Initiate infusion and breakfast
Start infusion of either GLP-1 (50 pmol/kg.h) or saline simultaneously with initiation of the energy-fixed breakfast test meal
Note: Infusion and meal initiation are synchronized
View evidence from paper
“Infusion (GLP-1, 50 pmol/kg.h or saline) was started simultaneously with initiation of the test meals”
Assess appetite sensations
Use visual analogue scales to assess subjective appetite sensations throughout the experiment following the energy-fixed breakfast
Note: Measurements taken after breakfast to assess satiety and fullness
View evidence from paper
“Visual analogue scales were used to assess appetite sensations throughout the experiment and the palatability of the test meals”
Collect blood samples
Sample blood throughout the day for analysis of plasma hormone and substrate levels
Note: Multiple time points collected to assess plasma GLP-1, insulin, glucagon, and blood glucose profiles
View evidence from paper
“Blood was sampled throughout the day for analysis of plasma hormone and substrate levels”
Administer ad libitum lunch
Provide ad libitum lunch meal to measure spontaneous energy intake under GLP-1 or saline infusion
Note: Energy intake measured as primary outcome
View evidence from paper
“spontaneous energy intake at the ad libitum lunch was reduced by 12% by GLP-1 infusion compared with saline”
Assess meal palatability
Use visual analogue scales to assess the palatability of the test meals
Note: Palatability assessed alongside appetite sensations
View evidence from paper
“Visual analogue scales were used to assess appetite sensations throughout the experiment and the palatability of the test meals”