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INTRODUCTION

In the endocrine pancreas, the islets of Langerhans produce several types of hormones. The hormones include insulin, the anabolic hormone (produced by B or beta cells); glucagon, the hyperglycemic factor (A or alpha cells); amylin, which modulates appetite (beta cells); somatostatin, the universal inhibitor of secretion (delta cells); and pancreatic polypeptide, facilitating digestion (F cells). Of these, the B (insulin-producing) cells are the most numerous.

The most common pancreatic disease requiring pharmacologic therapy is diabetes mellitus, a deficiency of insulin production or effect. Diabetes is treated with several parenteral formulations of insulin and oral or parenteral noninsulin antidiabetic agents. Glucagon, a hormone that affects the liver, cardiovascular system, and gastrointestinal tract, can be used to treat severe hypoglycemia.

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DIABETES MELLITUS

Diabetes mellitus is classified into four categories: type 1, type 2, other, and gestational diabetes mellitus. In this chapter we focus on type 1 and type 2. Type 1 diabetes usually has its onset during childhood and results from autoimmune destruction of pancreatic B cells. Type 2 diabetes is a progressive disorder characterized by increasing insulin resistance and diminishing insulin secretory capacity. Latent autoimmune diabetes of adulthood (LADA) is a mild autoimmune form found in 10–15% of type 2 diabetes patients. Type 2 diabetes is frequently associated with obesity and is much more common than type 1 diabetes. Although type 2 diabetes usually has its onset in adulthood, the incidence in children and adolescents is rising dramatically, in parallel with the increase in obesity in this population.

The clinical history and course of these two forms differ considerably, but treatment in both cases requires careful attention to diet, fasting and postprandial blood glucose concentrations, and serum concentrations of hemoglobin A1c, a glycosylated hemoglobin that serves as a marker of chronic glycemia. Type 1 diabetes requires treatment with insulin. The early stages of type 2 diabetes usually can be controlled with noninsulin antidiabetic drugs. However, patients in the later stages of type 2 diabetes often require the addition of insulin to their drug regimen.

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High-Yield Terms to Learn
Alpha-glucosidase An enzyme in the gastrointestinal tract that converts complex starches and oligosaccharides to monosaccharides; inhibited by acarbose and miglitol
Beta (B) cells in the islets of Langerhans Insulin-producing cells in the endocrine pancreas
Hypoglycemia Dangerously lowered serum glucose concentration; a potential toxic effect of high insulin concentrations and the secretagogue class of oral antidiabetic drugs
Lactic acidosis Acidemia due to excess serum lactic acid; can result from excess production or decreased metabolism of lactic acid
Type 1 diabetes mellitus A form of chronic hyperglycemia caused by immunologic destruction of pancreatic beta cells
Type 2 diabetes mellitus A form of chronic hyperglycemia initially caused by resistance to insulin; often progresses to insulin deficiency

INSULIN

A. Physiology

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