Incretins in fibrocalculous pancreatic diabetes: A unique subtype of pancreatogenic diabetes

Abstract Background Studies evaluating endocrine and exocrine functions in fibrocalculous pancreatic diabetes (FCPD) are scarce. Methods Insulin, C‐peptide, glucagon, incretin hormones (glucagon‐like peptide 1 [GLP‐1] and gastric inhibitory peptide [GIP]), and dipeptidyl peptidase IV (DPP‐IV) were estimated in patients with FCPD (n = 20), type 2 diabetes mellitus (T2DM) (n = 20), and controls (n = 20) in fasting and 60 minutes after 75 g glucose. Results Fasting and post‐glucose C‐peptide and insulin in FCPD were lower than that of T2DM and controls. Plasma glucagon decreased after glucose load in controls (3.72, 2.29), but increased in T2DM (4.01, 5.73), and remained unchanged in FCPD (3.44, 3.44). Active GLP‐1 (pmol/L) after glucose load increased in FCPD (6.14 to 9.72, P = <.001), in T2DM (2.87 to 4.62, P < .001), and in controls (3.91 to 6.13, P < .001). Median active GLP‐1 in FCPD, both in fasting and post‐glucose state (6.14, 9.72), was twice that of T2DM (2.87, 4.62) and 1.5 times that of controls (3.91, 6.13) ( P < .001 for all). Post‐glucose GIP (pmol/L) increased in all: FCPD (15.83 to 94.14), T2DM (21.85 to 88.29), and control (13.00 to 74.65) ( P < .001 for all). GIP was not different between groups. DPP‐IV concentration (ng/mL) increased in controls (1578.54, 3012.00) and FCPD (1609.95, 1995.42), but not in T2DM (1204.50, 1939.50) ( P = .131). DPP‐IV between the three groups was not different. Fecal elastase was low in FCPD compared with T2DM controls. Conclusions In FCPD, basal C‐peptide and glucagon are low, and glucagon does not increase after glucose load. GLP‐1, but not GIP, in FCPD increases 1.5 to 2 times as compared with T2DM and controls (fasting and post glucose) without differences in DPP‐IV.