Endocrine Pancreas and Diabetes Mellitus Overview

Study Notes

Produces several hormones including insulin, glucagon, somatostatin, and gastrin.
Insulin is the storage and anabolic hormone.
Glucagon is the hyperglycemic factor that mobilizes glycogen stores.
Somatostatin inhibits secretory cells.
Gastrin stimulates gastric acid secretion.

Defined as elevated blood glucose with absent or inadequate insulin secretion, with or without insulin action impairment.
Classified into Type 1, Type 2, Type 3, and Type 4.

Characterized by beta cell destruction and severe insulin deficiency.
Subdivided into immune and idiopathic causes.
Often diagnosed in individuals younger than 30 years old.
Requires insulin replacement therapy for survival.
Diabetic ketoacidosis is a potential complication due to insufficient insulin and excess fatty acid release.

Characterized by tissue resistance to insulin and relative deficiency in insulin secretion.
10–20% of individuals initially diagnosed with Type 2 Diabetes may actually have Type 1 or LADA (latent autoimmune diabetes of adults).
Dehydration in untreated or poorly controlled Type 2 Diabetes can lead to non-ketotic hyperosmolar coma.

Refers to multiple other specific causes of elevated blood glucose, including pancreatectomy, pancreatitis, non-pancreatic diseases, and drug therapy.

Gestational Diabetes (GDM) is defined as any glucose level abnormality during pregnancy.

Small protein with a molecular weight of 5808 in humans.
Contains 51 amino acids arranged in two chains (A and B) linked by disulfide bridges.
Proinsulin is a long single-chain protein processed within beta cells and hydrolyzed into insulin and C-peptide.
The human pancreas contains up to 8 mg of insulin (approximately 200 biological units).

Released from pancreatic beta cells at a basal rate and stimulated by multiple factors, especially glucose.
Other stimulants include other sugars, amino acids, hormones like GLP-1 and GIP, fatty acids, and beta-adrenergic sympathetic activity.
Stimulatory drugs: sulfonylureas, meglitinides, isoproterenol, and acetylcholine.
Inhibitory signals: insulin itself, leptin, alpha-adrenergic sympathetic activity, high glucose levels, and low fatty acid concentrations.
Inhibitory drugs: diazoxide, phenytoin, vinblastine, and colchicine.

The liver (60%) and kidney (35-40%) are the main organs for insulin removal from circulation.
In insulin-treated diabetics receiving subcutaneous insulin injections, the kidney removes up to 60% of exogenous insulin.

Basal insulin values in normal individuals range from 5–15 μU/mL (30–90 pmol/L).
Peak levels reach 60–90 μU/mL (360–540 pmol/L) after meals.

Insulin binds to its receptor, initiating a cascade of intracellular signaling events.

Available in rapid-acting, short-acting, intermediate-acting, and long-acting forms.
Rapid-acting and short-acting insulin are clear solutions containing zinc for stability and shelf life.
Intermediate-acting NPH insulin is a turbid suspension containing protamine in phosphate buffer.