224-LB: A Study to Evaluate the Glucagon and Incretin Responses and Identify the Role of Extrapancreatic Glucagon in Patients with Fibrocalcific Pancreatic Diabetes

Abstract

Aim: The aim of this study is to evaluate glucagon and incretin responses in patients with FCPD. Methods: Nine FCPD patients and six age- and body mass index-matched healthy controls were subjected to 75 g oral glucose tolerance test (OGTT) followed by isoglycemic intravenous glucose infusion (IIGI). Blood samples were analyzed for incretins and glucagon at nine pre-specified time-points over 3 h and the area under curve was calculated. Results: Glucagon was significantly higher during OGTT compared to IIGI in FCPD patients (98.8 ± 13 pg/ml vs. 63.4 ± 7 pg/ml, P = 0.03) and was also higher when compared to controls (98.8 ± 13 pg/ ml vs. 65.8 ± 18 pg/ml, P = ns). FCPD patients showed very low basal and stimulated c-peptide (0.43 ± 0.14 ng/ml and 1.09 ± 0.3 ng/ ml, respectively) and pancreatic polypeptide (12.3 ± 0.0pg/ml and 12.0 ± 0.6 pg/ml, respectively) levels. Glucagon-like peptide-1 (GLP-1) was significantly higher in cases on OGTT when compared to controls (44.5 ± 9.2 pM vs. 12.8 ± 7.5 pM, P = 0.02). Oxyntomodulin was also insignificantly higher in cases on OGTT when compared to controls (1252 ± 350 pg/ml vs. 859.8 ± 165 pg/ml, P = 0.43). GIP was lower in cases on IIGI when compared to controls (52.9 ± 23.9 pg/ml vs. 144.5 ± 36.1 pg/ml, P = 0.045) and there was blunted response on OGTT as well (106.8 ± 40.3 pg/ml vs. 557.8 ± 96.4 pg/ml, P = 0.003). Discussion: We found hyperglucagonemia in FCPD on OGTT, which was suppressed on IIGI. Increase in L-cell products: GLP-1 and oxyntomodulin and a good correlation between glucagon and GLP-1 during OGTT were suggestive of extrapancreatic glucagon production probably from L-cell. The blunted GIP could probably be due to: inadequate pancreatic enzyme supplements, a selective PC-2 enzyme up-regulation or a negative feedback regulation from extrapancreatic glucagon. Conclusion: Extrapancreatic glucagon does exist in FCPD and may contribute to postprandial hyperglycemia and lower GIP levels. Disclosure A. Shankar: None.