A meta-analysis of the effect of glucagon-like peptide-1 (7-36) amide on ad libitum energy intake in humans

Seven studies have now been published pertaining to the acute effect of iv administration of glucagon-like peptide-1 (7-36) amide on ad libitum energy intake. In four of these studies energy intake was significantly reduced f ollowing the glucagon-like peptide-1 infusion compared with saline. In the remaining studies, no significant effect of glucagon-like peptide-1 could b e shown. Lack of statistical power or low glucagon-like peptide-1 infusion rate may explain these conflicting results. Our aim was to examine the effect of glucagon-like peptide-1 on subsequent energy intake using a data set composed of subject data from previous studi es and from two as yet unpublished studies. Secondly, we investigated wheth er the effect on energy intake is dose dependent and differs between lean a nd overweight subjects. Raw subject data on body mass index and ad libitum energy intake were colle cted into a common data set (n=115), together with study characteristics su ch as infusion rate, duration of infusion, etc. From four studies with comp arable protocol the following subject data were included if available: plas ma concentrations of glucagon-like peptide-1, subjective appetite measures, well-being, and gastric emptying rate of a meal served at the start of the glucagon-like peptide-1 infusion. Energy intake was reduced by 727 kJ (95% confidence interval, 548-908 kJ) o r 11.7% during glucagon-like peptide-1 infusion. Although the absolute redu ction in energy intake was higher in lean (863 kJ) (634-1091 kJ) compared w ith overweight subjects (487 kJ) (209-764 kJ) (P=0.05), the relative reduct ion did not differ between the two groups (13.2% and 9.3%, respectively). S tepwise regression analysis showed that the glucagon-like peptide-1 infusio n rate was the only independent predictor of the reduction in energy intake during glucagon-like peptide-1 (7-36) amide infusion (r=0.4, P<0.001). Dif ferences in mean plasma glucagon-like peptide-1 concentration on the glucag on-like peptide-1 and placebo day (n=43) were related to differences in fee lings of prospective consumption (r=0.40, P<0.01), fullness (r=0.38, P<0.05 ), and hunger (r=0.26, P=0.09), but not to differences in ad libitum energy intake. Gastric emptying rate was significantly lower during glucagon-like peptide-1 infusion compared with saline. Finally, well-being was not influ enced by the glucagon-like peptide-1 infusion. Glucagon-like peptide-1 infusion reduces energy intake dose dependently in both lean and overweight subjects. A reduced gastric emptying rate may cont ribute to the increased satiety induced by glucagon-like peptide-1.