Insulin is a peptide hormone produced by beta cells of the pancreatic islets encoded in humans by the insulin (INS) gene. It is the main anabolic hormone of the body. It regulates the metabolism of carbohydrates, fats, and protein by promoting the absorption of glucose from the blood into cells of the liver, fat, and skeletal muscles. In these tissues the absorbed glucose is converted into either glycogen, via glycogenesis, or fats (triglycerides), via lipogenesis; in the liver, glucose is converted into both. Glucose production and secretion by the liver are strongly inhibited by high concentrations of insulin in the blood. Circulating insulin also affects the synthesis of proteins in a wide variety of tissues. It is thus an anabolic hormone, promoting the conversion of small molecules in the blood into large molecules in the cells. Low insulin in the blood has the opposite effect, promoting widespread catabolism, especially of reserve body fat.
Beta cells (β-cells) are specialized endocrine cells located within the pancreatic islets of Langerhans responsible for the production and release of insulin and amylin. Constituting ~50–70% of cells in human islets, beta cells play a vital role in maintaining blood glucose levels. Problems with beta cells can lead to disorders such as diabetes.
The pancreatic islets or islets of Langerhans are the regions of the pancreas that contain its endocrine (hormone-producing) cells, discovered in 1869 by German pathological anatomist Paul Langerhans. The pancreatic islets constitute 1–2% of the pancreas volume and receive 10–15% of its blood flow. The pancreatic islets are arranged in density routes throughout the human pancreas, and are important in the metabolism of glucose.
Glimepiride is an antidiabetic medication within the sulfonylurea class, primarily prescribed for the management of type 2 diabetes. It is regarded as a second-line option compared to metformin, due to metformin's well-established safety and efficacy. Use of glimepiride is recommended in conjunction with lifestyle modifications such as diet and exercise. It is taken by mouth, reaching a peak effect within three hours and lasting for about a day.
Drugs used in diabetes treat diabetes mellitus by decreasing glucose levels in the blood. With the exception of insulin, most GLP-1 receptor agonists, and pramlintide, all diabetes medications are administered orally and are thus called oral hypoglycemic agents or oral antihyperglycemic agents. There are different classes of hypoglycemic drugs, and selection of the appropriate agent depends on the nature of diabetes, age, and situation of the person, as well as other patient factors.
Verapamil, sold under various trade names, is a calcium channel blocker medication used for the treatment of high blood pressure, angina, and supraventricular tachycardia. It may also be used for the prevention of migraines and cluster headaches. It is given by mouth or by injection into a vein.
Alpha cells (α-cells) are endocrine cells that are found in the Islets of Langerhans in the pancreas. Alpha cells secrete the peptide hormone glucagon in order to increase glucose levels in the blood stream.
Diazoxide, sold under the brand name Proglycem and others, is a medication used to treat low blood sugar due to a number of specific causes. This includes islet cell tumors that cannot be removed and leucine sensitivity. It can also be used in refractory cases of sulfonylurea toxicity. It is generally taken by mouth.
Glibenclamide, also known as glyburide, is an antidiabetic medication used to treat type 2 diabetes. It is recommended that it be taken together with diet and exercise. It may be used with other antidiabetic medication. It is not recommended for use by itself in type 1 diabetes. It is taken by mouth.
Type 1 diabetes (T1D), formerly known as juvenile diabetes, is an autoimmune disease that originates when cells that make insulin are destroyed by the immune system. Insulin is a hormone required for the cells to use blood sugar for energy and it helps regulate glucose levels in the bloodstream. Before treatment this results in high blood sugar levels in the body. The common symptoms of this elevated blood sugar are frequent urination, increased thirst, increased hunger, weight loss, and other serious complications. Additional symptoms may include blurry vision, tiredness, and slow wound healing. Symptoms typically develop over a short period of time, often a matter of weeks if not months.
Exenatide, sold under the brand name Byetta among others, is a medication used to treat type 2 diabetes. It is used together with diet, exercise, and potentially other antidiabetic medication. It is a treatment option after metformin and sulfonylureas. It is given by injection under the skin.
Repaglinide is an antidiabetic drug in the class of medications known as meglitinides, and was invented in 1983. Repaglinide is a medication used in addition to diet and exercise for blood sugar control in type 2 diabetes. The mechanism of action of repaglinide involves promoting insulin release from β-islet cells of the pancreas; like other antidiabetic drugs, a main side effect concern is hypoglycemia. It is sold by Novo Nordisk under the name of Prandin in the United States, Gluconorm in Canada, Surepost in Japan, Repaglinide in Egypt, and Novonorm elsewhere. In Japan it is produced by Dainippon Sumitomo Pharma.
Gliclazide, sold under the brand name Diamicron among others, is a sulfonylurea type of anti-diabetic medication, used to treat type 2 diabetes. It is used when dietary changes, exercise, and weight loss are not enough. It is taken by mouth.
Sitagliptin, sold under the brand name Januvia among others, is an anti-diabetic medication used to treat type 2 diabetes. In the United Kingdom it is listed as less preferred than metformin or a sulfonylurea. It is taken by mouth. It is also available in the fixed-dose combination medication sitagliptin/metformin.
The insulin concentration in blood increases after meals and gradually returns to basal levels during the next 1–2 hours. However, the basal insulin level is not stable. It oscillates with a regular period of 3-6 min. After a meal the amplitude of these oscillations increases but the periodicity remains constant. The oscillations are believed to be important for insulin sensitivity by preventing downregulation of insulin receptors in target cells. Such downregulation underlies insulin resistance, which is common in type 2 diabetes. It would therefore be advantageous to administer insulin to diabetic patients in a manner mimicking the natural oscillations. The insulin oscillations are generated by pulsatile release of the hormone from the pancreas. Insulin originates from beta cells located in the islets of Langerhans. Since each islet contains up to 2000 beta cells and there are one million islets in the pancreas it is apparent that pulsatile secretion requires sophisticated synchronization both within and among the islets of Langerhans.
Insulitis is an inflammation of the islets of Langerhans, a collection of endocrine tissue located in the pancreas that helps regulate glucose levels, and is classified by specific targeting of immune cell infiltration in the islets of Langerhans. This immune cell infiltration can result in the destruction of insulin-producing beta cells of the islets, which plays a major role in the pathogenesis, the disease development, of type 1 and type 2 diabetes. Insulitis is present in 19% of individuals with type 1 diabetes and 28% of individuals with type 2 diabetes. It is known that genetic and environmental factors contribute to insulitis initiation, however, the exact process that causes it is unknown. Insulitis is often studied using the non-obese diabetic (NOD) mouse model of type 1 diabetes. The chemokine family of proteins may play a key role in promoting leukocytic infiltration into the pancreas prior to pancreatic beta-cell destruction.
Regular insulin, also known as neutral insulin and soluble insulin, is a type of short-acting medical insulin. It is used to treat type 1 diabetes, type 2 diabetes, gestational diabetes, and complications of diabetes such as diabetic ketoacidosis and hyperosmolar hyperglycemic states. It is also used along with glucose to treat high blood potassium levels. Typically it is given by injection under the skin, but may also be used by injection into a vein or muscle. Onset of effect is typically in 30 minutes and it typically lasts for 8 hours.
Linagliptin, sold under the brand name Tradjenta among others, is a medication used to treat type 2 diabetes in conjunction with exercise and diet. It is generally less preferred than metformin and sulfonylureas as an initial treatment. It is taken by mouth.
Sitagliptin/metformin, sold under the brand name Janumet among others, is a fixed-dose combination anti-diabetic medication used to treat type 2 diabetes. It may be used in those whose blood sugar is not controlled with metformin and a sulfonylurea. It is taken by mouth.
Dulaglutide, sold under the brand name Trulicity among others, is a medication used for the treatment of type 2 diabetes in combination with diet and exercise. It is also approved in the United States for the reduction of major adverse cardiovascular events in adults with type 2 diabetes who have established cardiovascular disease or multiple cardiovascular risk factors. It is a once-weekly injection.
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