Effect of glucagon-like peptide 1(7-36)amide in insulin-treated patients with diabetes mellitus secondary to chronic pancreatitis

Diabetes of the Exocrine Pancreas: Implications for Pharmacological Management

Post-pancreatitis diabetes mellitus, pancreatic cancer-related diabetes, and cystic fibrosis-related diabetes are often underappreciated. As a result, a substantial proportion of people with these sub-types of diabetes receive antidiabetic medications that may be suboptimal, if not harmful, in the context of their underlying disease of the exocrine pancreas. The present article delineates both classical (biguanides, insulin, sulfonylureas, α-glucosidase inhibitors, thiazolidinediones, and meglitinides) and newer (glucagon-like peptide-1 receptor agonists, amylin analogs, dipeptidyl peptidase-4 inhibitors, sodium-glucose co-transporter-2 inhibitors, D2 receptor agonists, bile acid sequestrants, and dual glucagon-like peptide-1 receptor and glucose-dependent insulinotropic polypeptide receptor co-agonists) therapies and provides recommendations for managing people with diabetes of the exocrine pancreas based on the most up-to-date clinical evidence. Also, several emerging directions (lipid-enriched pathways, Y4 receptor agonism, glucagon-like peptide-1 and glucagon receptor co-agonism) are presented with a view to informing the process of new drug discovery and development.

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

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.

Pathological Mechanisms in Diabetes of the Exocrine Pancreas: What's Known and What's to Know

The clinical significance of diabetes arising in the setting of pancreatic disease (also known as diabetes of the exocrine pancreas, DEP) has drawn more attention in recent years. However, significant improvements still need to be made in the recognition, diagnosis and treatment of the disorder, and in the knowledge of the pathological mechanisms. The clinical course of DEP is different from type 1 diabetes mellitus (T1DM) and type 2 diabetes mellitus (T2DM). DEP develops in patients with previous existing exocrine pancreatic disorders which damage both exocrine and endocrine parts of pancreas, and lead to pancreas exocrine insufficiency (PEI) and malnutrition. Therefore, damage in various exocrine and endocrine cell types participating in glucose metabolism regulation likely contribute to the development of DEP. Due to the limited amount of clinical and experimental studies, the pathological mechanism of DEP is poorly defined. In fact, it still not entirely clear whether DEP represents a distinct pathologic entity or is a form of T2DM arising when β cell failure is accelerated by pancreatic disease. In this review, we include findings from related studies in T1DM and T2DM to highlight potential pathological mechanisms involved in initiation and progression of DEP, and to provide directions for future research studies.

Type 3c (pancreatogenic) diabetes mellitus secondary to chronic pancreatitis and pancreatic cancer

Diabetes mellitus is a group of diseases defined by persistent hyperglycaemia. Type 2 diabetes, the most prevalent form, is characterised initially by impaired insulin sensitivity and subsequently by an inadequate compensatory insulin response. Diabetes can also develop as a direct consequence of other diseases, including diseases of the exocrine pancreas. Historically, diabetes due to diseases of the exocrine pancreas was described as pancreatogenic or pancreatogenous diabetes mellitus, but recent literature refers to it as type 3c diabetes. It is important to note that type 3c diabetes is not a single entity; it occurs because of a variety of exocrine pancreatic diseases with varying mechanisms of hyperglycaemia. The most commonly identified causes of type 3c diabetes are chronic pancreatitis, pancreatic ductal adenocarcinoma, haemochromatosis, cystic fibrosis, and previous pancreatic surgery. In this Review, we discuss the epidemiology, pathogenesis, and clinical relevance of type 3c diabetes secondary to chronic pancreatitis and pancreatic ductal adenocarcinoma, and highlight several important knowledge gaps.

Chronic Pancreatitis and Diabetes Mellitus

OPINION STATEMENT

Patients with chronic pancreatitis should be screening at least annually for diabetes. Lifestyle modifications remain to be an important part of treatment for diabetic control. Unless contraindicated or not tolerated, metformin can be initiated and continued concurrently with other anti-diabetic agents or insulin. All anti-diabetic agents should be used based on their physiology and adverse effect profiles, along with the metabolic status of patients. Insulin therapy should be initiated without delay for any of the following: symptomatic or overt hyperglycemia, catabolic state secondary to uncontrolled diabetes, history of diabetic ketoacidosis, hospitalization or acute exacerbation of pancreatitis, or hyperglycemia that cannot be otherwise controlled. Dose adjustment should be done conservatively as these patients are more likely to be insulin sensitive and have loss of counter regulatory hormones. Insulin pump and continuous glucose monitoring should be considered early during therapy in selected patients. For patients undergoing total pancreatectomy or extensive partial pancreatectomy, evaluations to determine the eligibilities for islet cell autotransplantation should be considered.

CCR2 knockout exacerbates cerulein-induced chronic pancreatitis with hyperglycemia via decreased GLP-1 receptor expression and insulin secretion

Glucagon-like peptide-1 (GLP-1) promotes insulin release; however, the relationship between the GLP-1 signal and chronic pancreatitis is not well understood. Here we focus on chemokine (C-C motif) ligand 2 (CCL2) and its receptor (CCR2) axis, which regulates various immune cells, including macrophages, to clarify the mechanism of GLP-1-mediated insulin secretion in chronic pancreatitis in mice. One and multiple series of repetitive cerulein administrations were used to induce acute and chronic cerulein pancreatitis, respectively. Acute cerulein-administered CCR2-knockout (KO) mice showed suppressed infiltration of CD11b(+)Gr-1(low) macrophages and pancreatic inflammation and significantly upregulated insulin secretion compared with paired wild-type (WT) mice. However, chronic cerulein-administered CCR2-KO mice showed significantly increased infiltration of CD11b(+)/Gr-1(-) and CD11b(+)/Gr-1(high) cells, but not CD11b(+)/Gr-1(low) cells, in pancreas with severe inflammation and significantly decreased insulin secretion compared with their WT counterparts. Furthermore, although serum GLP-1 levels in chronic cerulein-administered WT and CCR2-KO mice were comparably upregulated after cerulein administrations, GLP-1 receptor levels in pancreases of chronic cerulein-administered CCR2-KO mice were significantly lower than in paired WT mice. Nevertheless, a significantly higher hyperglycemia level in chronic cerulein-administered CCR2-KO mice was markedly restored by treatment with a GLP-1 analog to a level comparable to the paired WT mice. Collectively, the CCR2/CCL2 axis-mediated CD11b(+)-cell migration to the pancreas is critically involved in chronic pancreatitis-mediated hyperglycemia through the modulation of GLP-1 receptor expression and insulin secretion.

The complex exocrine-endocrine relationship and secondary diabetes in exocrine pancreatic disorders

The pancreas is a dual organ with exocrine and endocrine functions. The interrelationship of the endocrine-exocrine parts of the pancreas is a complex one, but recent clinical and experimental studies have expanded our knowledge. Many disorders primarily of the exocrine pancreas, often solely in the clinical realm of gastroenterologists are associated with diabetes mellitus (DM). Although, the DM becoming disorders are often grouped with type 2 diabetes, the pathogenesis, clinical manifestations and management differ. We review here data on the association of exocrine-endocrine pancreas, the many hormones of the pancreas and their possible effects on the exocrine functions followed by data on the epidemiology, pathogenesis, and management of DM in chronic pancreatitis, cystic fibrosis, pancreatic cancer, and clinical states after pancreatic surgery.

Interactions between the endocrine and exocrine pancreas and their clinical relevance

In consequence of the close anatomical and functional links between the exocrine and endocrine pancreas, any disease affecting one of these parts will inevitably affect the other. Pancreatic conditions which might cause diabetes mellitus include acute and chronic pancreatitis, pancreatic surgery, cystic fibrosis and pancreatic cancer. The development of diabetes greatly influences the prognosis and quality of life of patients with exocrine pancreatic diseases. It may cause life-threatening complications, such as hypoglycemia, due to the lack of glucagon and the impaired absorption of nutrients, or the micro- and macrovascular complications may impair the organ functions. Diabetes mellitus is an independent risk factor of mortality in those with exocrine pancreatic diseases. The treatment of pancreatic diabetes, a distinct metabolic and clinical form of diabetes, requires special knowledge. Diet and pancreatic enzyme replacement therapy may be sufficient in the early stages. Oral antidiabetic drugs are not recommended. If the diet proves inadequate to reach the glycemic goals, insulin treatment with multiple injections is required. Impairments of the exocrine pancreatic function and morphology in diabetic patients are frequent and well known. Atrophy of the exocrine tissue may be caused by the lack of trophic insulin, whereas pancreatic fibrosis can result from activation of stellate cells by hyperglycemia, or from microangiopathy and neuropathy. The regulation of the exocrine pancreatic function is also damaged because of the impaired effect of islet hormones. In the event of a proven impairment of the pancreatic exocrine function in diabetes mellitus, pancreatic enzyme replacement therapy is indicated. This may improve the nutritional condition of the patient and decrease the metabolic instability.

Mechanisms and emerging treatments of the metabolic complications of chronic pancreatitis

OBJECTIVES

Exocrine and endocrine abnormalities in chronic pancreatitis contribute to the morbidity and mortality risks of the disease. Complications of exocrine insufficiency include malabsorption, vitamin deficiency syndromes, and weight loss. Oral enzyme replacement therapy is usually effective if attention is paid to factors that affect the bioavailability of enzyme preparations. Complications of endocrine insufficiency can be more difficult to treat due in part to an incomplete knowledge of their etiology.

METHODS

This review focuses on the endocrine aspects of chronic pancreatitis and highlights the observations of our laboratory on the pathogenesis of the metabolic complications of the disease.

RESULTS

In addition to decreased insulin secretory capacity, pancreatogenic (or apancreatic) diabetes is characterized by decreased or absent glucagon and pancreatic polypeptide (PP) secretion, a loss of hepatic insulin receptor (IR) expression/availability, and an impairment in hepatic IR function (phosphorylation and endocytosis). Diminished hepatic IR expression in chronic pancreatitis appears to be because of PP deficiency; laboratory animals and patients with PP deficiency demonstrate decreased hepatic IR availability that is reversed by prolonged (8-hour) PP administration. The impairment in hepatic IR function appears independent of PP deficiency but is reversed by prolonged (28-day) treatment with the insulinotropic/insulinomimetic hormone glucagon-like peptide 1. The endocytosis of hepatic IR is linked to the endocytosis of the glucose transporter 2 from the hepatocyte plasma membrane, and studies suggest that the 2 plasma membrane-bound proteins are complexed noncovalently to function and translocate as a unit after insulin binding to the hepatic IR. The process appears vigorous and sensitive enough to account for a significant reduction in hepatic glucose output and may represent a major mechanism for insulin regulation of hepatic glucose production.

CONCLUSIONS

The regulatory mechanisms of PP-mediated hepatic IR expression and combined IR and GLUT2 endocytosis after insulin binding are defective in chronic pancreatitis and contribute to the apancreatic diabetes, which characterizes this disease.