Plasma GDF15 levels are similar between subjects after bariatric surgery and matched controls and are unaffected by meals

Growth differentiating factor 15 (GDF15) is expressed in the intestine and is one of the most recently identified satiety peptides. The mechanisms controlling its secretion are unclear. The present study investigated whether plasma GDF15 concentrations are meal-related and if potential responses depend on macronutrient type or are affected by previous bariatric surgery. The study included: (1) volunteers ingesting rapidly vs. slowly digested carbohydrates (sucrose vs. isomaltose) (n=10), (2) volunteers who had undergone Roux-en-Y Gastric bypass (RYGB) or sleeve gastrectomy (SG) surgery and unoperated matched controls ingesting a liquid mixed meal (n=9-10 in each group), and (3) individuals with previous RYGB compared with unoperated controls ingesting isocaloric glucose, fat or protein (n=6 in each group). Plasma was collected after an overnight fast and up to 6 h after ingestion (≥12 timepoints). In cohort 1, fasting GDF15 concentrations were ~480 pg/ml. Concentrations after sucrose or isomaltose intake did not differ from baseline (P=0.26-P>0.99) and total area-under-the-curves (tAUCs were similar between groups (P=0.77). In cohort 2, fasting GDF15 concentrations were (pg/ml): RYGB=540±41.4, SG=477±36.4, and controls=590±41.8, with no between-group differences (P=0.73). Concentrations did not increase at any postprandial time point (over all time factor: P=0.10) and tAUCs were similar between groups (P=0.73). In cohort 3, fasting plasma GDF15 was similar among the groups (P>0.99) and neither glucose, fat or protein intake consistently increased the concentrations. In conclusion, we find that plasma GDF15 was not stimulated by meal intake, and that fasting concentrations did not differ between RYGB, SG and BMI-matched controls when investigated during the weight stable phase after RYGB and SG.