Incretin hormones and beta cell function in chronic pancreatitis

Area of Science:

• Endocrinology
• Gastroenterology
• Metabolic Diseases

Background:

• Type 2 diabetes mellitus (T2DM) is characterized by a diminished incretin effect, where oral glucose yields a lower insulin response than intravenous glucose.
• The incretin effect is mediated by glucagon-like peptide-1 (GLP-1) and glucose-dependent insulinotropic polypeptide (GIP), secreted by the small intestine in response to nutrients.
• The cause of the T2DM incretin defect—whether primary or secondary to the diabetic state—remains unclear.

Purpose of the Study:

• To investigate whether the incretin deficiencies observed in T2DM are a primary cause or a consequence of the diabetic state.
• To examine incretin hormone secretion and effect in patients with chronic pancreatitis (CP) and secondary diabetes mellitus (DM).

Main Methods:

• Studied postprandial incretin responses in patients with CP (with and without pancreatic enzyme supplementation) compared to healthy subjects.
• Assessed the incretin effect in patients with CP and normal glucose tolerance, CP with secondary DM, healthy controls, and T2DM patients.
• Evaluated the insulinotropic effect of incretin hormones in patients with CP and secondary DM compared to controls.

Main Results:

• Pancreatic enzyme supplementation improved postprandial incretin responses in CP patients, indicating nutrient assimilation's role in secretion.
• The incretin effect was preserved in CP patients with normal glucose tolerance but significantly reduced in those with secondary DM.
• Patients with CP and secondary DM showed an impaired insulinotropic effect of GIP, suggesting it's a consequence of the diabetic state.

Conclusions:

• Postprandial incretin hormone secretion is preserved in chronic pancreatitis patients.
• Nutrient assimilation in the small intestine stimulates the secretion of GIP and GLP-1.
• The incretin deficiencies characteristic of T2DM likely arise as a consequence of impaired glucose homeostasis, rather than being a primary etiological factor.