Pancreatic Effects of Liraglutide or Sitagliptin in Overweight Patients With Type 2 Diabetes: A 12-Week Randomized, Placebo-Controlled Trial

OBJECTIVE To assess the mechanistic effects of the glucagon-like peptide 1 (GLP-1) receptor agonist liraglutide and the dipeptidyl peptidase 4 (DPP-4) inhibitor sitagliptin on (exocrine) pancreatic physiology and morphology. RESEARCH DESIGN AND METHODS For this randomized, double-blind, parallel-group trial, 55 patients with type 2 diabetes treated with metformin and/or sulfonylurea agents were included. Participants received liraglutide 1.8 mg (n = 19), sitagliptin 100 mg (n = 19), ormatching placebos (n = 17) once daily for 12 weeks. The primary end point was change in exocrine function (intraduodenal pancreatic fluid secretion, lipase activity, fecal elastase-1, and chymotrypsin). Secondary end points included changes in plasma enzyme concentrations and pancreatic morphology (per MRI). RESULTS No patient developed pancreatitis. Sitagliptin increased intraduodenal pancreatic fluid secretion by 16.3 mL (95% CI 20.3 to 32.9; P = 0.05), whereas liraglutide did not change exocrine pancreatic function. Neither therapy increased lipase/ amylase levels after 12 weeks. However, liraglutide increased lipase levels after 6 weeks (23.5 U/L [95% CI 2.1-44.8]; P = 0.03) and sitagliptin increased amylase levels after 2 and 6 weeks (13.7 U/L [95% CI 3.4-23.9]; P = 0.03). Both drugs increased plasma trypsinogen after 12 weeks (liraglutide: 34.6 mg/mL [95% CI 15.1-54.2], P = 0.001; sitagliptin: 23.9 mg/mL [95% CI 4.9-42.9], P = 0.01). Neither changed pancreatic morphology, although liraglutide tended to increase pancreatic volume (7.7 cm3 [95% CI 21.2 to 16.6]; P = 0.09). Treatment-induced volume expansion was associated with increased amylase levels. CONCLUSIONS A 12-week treatment with liraglutide or sitagliptin only resulted in a brief and modest increase of plasma pancreatic enzyme concentrations in patients with type 2 diabetes. Apart from a minimal sitagliptin-induced increase in intraduodenal fluid secretion, pancreatic exocrine function was unaffected. The long-term clinical consequences of these discrete changes require further study.