Insulin
Ben Greenstein in Rapid Revision in Endocrinology, 2017
This chapter examines the main physiological actions of insulin, discusses the inverse relationship between circulating glucose and insulin, and presents a brief account of the mechanism of action of insulin. It explores the distinction between type 1 and type 2 diabetes, their aetiology, symptoms, complications and treatment. Insulin is an endocrine hormone, that is, secreted directly into the bloodstream from the hormone-producing endocrine cells of the pancreas. Exocrine secretions are via ducts from the glands, for example, secretion of pancreatic digestive juices via the pancreatic duct into the duodenum. Insulin is an anabolic hormone, that is, it promotes the elaboration of polymers from simpler molecules for the storage of energy resources and for the building up of tissues, for example, muscle. Insulin promotes removal of glucose from the circulation. Two molecules of insulin bind to a subunit on the extracellular domain of the membrane insulin receptor.
Dynamical Compensation and Mutant Resistance in Tissues
Uri Alon in An Introduction to Systems Biology, 2019
This chapter argues that new principles arise to allow organs to work robustly, keep the right functional size and resist mutants. Robustness must involve additional processes beyond the minimal model's glucose-insulin loop. Glucose causes beta cells to secrete the hormone insulin that is carried by the blood to all tissues. In dynamical compensation, tissue size grows and shrinks in order to precisely buffer the variation in parameters. Insulin is sensed by receptors in the cells of many tissues, and instructs the cells in the muscle, liver and fat to take up glucose from the blood, reducing blood glucose concentration. Pregnancy decreases mom's insulin sensitivity and hence diverts more glucose for the growth of the fetus – in pathological cases placing the mother at risk for diabetes. The circuit has a negative feedback loop similar to insulin-glucose, but with inverted signs: PTH causes increase of calcium, and calcium inhibits PTH secretion.
Insulins and insulin management
Janet Titchener in Diabetes Management, 2020
This chapter reviews the pharmacokinetics of traditional and analogue insulins, the pros and cons of each and the relative cost. The reader is also provided with a straightforward approach to calculating insulin doses, carbohydrate ratios and correction factors. An overview of the different insulin delivery systems is provided along with essential teaching points to cover with each patient when initiating insulin.
Possible roles of insulin signaling in osteoblasts
Published in Endocrine Research, 2014
Sakarat N. Pramojanee, Mattabhorn Phimphilai, Nipon Chattipakorn, Siriporn C. Chattipakorn
Insulin and its downstream signaling pathway are indispensable for postnatal bone growth and turnover by having influence on both osteoblast and osteoclast development. Insulin signaling regulates both bone formation by osteoblasts and bone resorption by osteoclasts; however, the regulation occurs mainly through the insulin signaling pathway within osteoblasts. An impairment of osteoblastic insulin signaling leads to an impaired bone quality by affecting osteoblast proliferation, differentiation and survival. The insulin signaling pathway and MAPK and PI3K/Akt pathways play pivotal roles in the differentiation, function and survival of bone cells. Current evidence suggests that osteoblastic insulin signaling not only modulates bone growth and turnover but is also required for energy metabolism. Several mice models with impaired insulin signaling exhibited both bone and metabolic phenotypes, including symptoms of low bone mass, obesity, glucose intolerance and insulin resistance. In this review, we discuss the key findings that suggest a pivotal role of osteoblastic insulin signaling in both bone and energy metabolism.
A primer on concentrated insulins: what an internist should know
Published in Postgraduate Medicine, 2016
Adrienne Barnosky, Lisa Shah, Farah Meah, Nicholas Emanuele, Mary Ann Emanuele, Alaleh Mazhari
The common insulin concentration in most preparations of insulin is 100 units per mL or U-100. Human regular U-500 insulin was the first concentrated insulin introduced and it has been available in the United States since the 1950s. Humulin R is the only human regular U-500 available on the market. Human regular U-500 is five times more concentrated than U-100 and because of its pharmacodynamic properties, works as both a basal and a bolus insulin. Human regular U500 allows for delivery of a larger insulin dose with a smaller volume leading to better absorption compared to U-100 and has traditionally been used in patients with moderate to severe insulin resistance. More recently other forms of concentrated insulin have become available and the newer concentrated insulin preparations can be used in diabetic patients with or without insulin resistance. Our intent is to provide primary care physicians with a review of the pharmacology and current literature on concentrated insulins as well as recommendations for patient selection, dose initiation, and dose adjustment.
Insulin amyloid at injection sites of patients with diabetes
Published in Amyloid, 2016
The formation of insulin amyloid can dramatically impact glycemic control in patients with diabetes, making it an important therapeutic consideration. In addition, the cost associated with the excess insulin required by patients with amyloid is estimated to be $3K per patient per year, which adds to the growing financial burden of this disease. Insulin amyloid has been observed with every mode of therapeutic insulin administration (infusion, injection and inhalation), and the number of reported cases has increased significantly since 2002. The new cases represent a much broader demographic, and include many patients who have used exclusively human insulin and human insulin analogs. The reason for the increase in case reports is unknown, but this review explores the possibility that changes in patient care, improved differential diagnosis and/or changes in insulin type and insulin delivery systems may be important factors. The goal of this review is to raise key questions that will inspire proactive measures to prevent, identify and treat insulin amyloid. Furthermore, this comprehensive examination of insulin amyloid can provide insight into important considerations for other injectable drugs that are prone to form amyloid deposits.
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