Insulins

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High Yield Notes

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Flashcards

Insulins

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A 26-year-old man comes to his primary care physician for a routine visit. He has no acute complaints and is feeling well. Medical history is notable for type I diabetes mellitus. The patient takes insulin glargine at night and insulin aspart three times a day before meals. He has been adherent to his medications but reports getting pre-prandial fingerstick glucose measurements of 120-145 mg/dL. Temperature is 37.1°C (98.8°F), pulse is 70/min, and blood pressure is 107/73 mmHg. The physical exam is non-contributory. Laboratory testing is ordered, revealing a fasting blood glucose of 130 mg/dL and hemoglobin A1c of 8.0%. Which of the following is the most appropriate next step in the management of this patient?  

External References

First Aid

2024

2023

2022

2021

Aspart insulin

β2 -agonists

insulin and p. 331

C-peptide

insulin and p. 331

in insulinomas p. 357

Detemir insulin

Glargine insulin

Glucagon p. 333

insulin and p. 331, 333

Gluconeogenesis p. 76

in insulin deficiency p. 350

Glucose

insulin and p. 333

Glulisine insulin

Glycogen p. 84

insulin and p. 331

Glycogenolysis

in insulin deficiency p. 350

Insulin p. 333

anabolic effects of p. 331

deficiency in p. 350

diabetic ketoacidosis p. 355

for HHNS p. 355

fructose bisphosphatase-2 and p. 74

GIP effect on p. 378

glucagon and p. 333

glycogen regulation p. 71, 84

hypokalemia from p. 608

in pregnancy p. 331

production of p. 337

secretion of p. 333

signaling pathways for p. 351

somatostatin and p. 378

somatostatinomas and p. 355

Insulinomas

insulin and C-peptide in p. 331

Insulin preparations p. 358

Ketogenesis

insulin deficiency p. 350

Lipolysis

insulin and p. 333

in insulin deficiency p. 350

Lispro insulin

Osmotic diuresis

insulin deficiency/insensitivity p. 350

Plasma osmolality

insulin deficiency/insensitivity p. 350

Pregnancy p. 651

insulin in p. 331

Protein synthesis p. 184, 196

insulin and p. 333

Proteolysis

in insulin deficiency p. 350

Regular insulin

Sulfonylureas p. 359

insulin and p. 331

Triglycerides

insulin and p. 331

Tyrosine kinase

insulin and p. 331

Transcript

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Insulin is a type of peptide hormone that reduces the amount of glucose in the blood. It is produced in the pancreas by beta cells. These cells are found within clusters of endocrine cells called the Islets of Langerhans, which are distributed across the pancreas. If the body is unable to produce enough insulin, then insulin therapy is used to keep the blood glucose low.

Insulin’s main function is to facilitate the transport of glucose from the blood into the various insulin-responsive tissues like muscle cells and adipose tissue. This hormone binds to insulin receptors on the surface of the cell membrane. Now, these receptors have two alpha and two beta subunits. Alpha subunits are located outside of the cell and they bind insulin; while two beta subunits are located within the cell and they have tyrosine kinase activity which carries signals into the cell. Once stimulated, insulin receptors cause intracellular storage vesicles, which contain glucose transport proteins called GLUT4, to fuse with the cell membrane. Next, the GLUT4 proteins embed themselves into the membrane and allow glucose to move into the cell.

As a result, insulin promotes glucose uptake and glycogenesis, which is the conversion of glucose to glycogen. Glycogenesis is the process that takes place in the liver and skeletal muscles. When glycogen storage capacity is reached, insulin promotes glycolysis, which is the breakdown of glucose to pyruvate. It also stimulates lipogenesis, the synthesis of fatty acids and triglycerides in the liver and adipose tissue; and amino acid uptake and protein synthesis in skeletal muscles.

Finally, insulin activates Na+/K+- ATPase pumps and shifts potassium into intracellular space, thereby decreasing potassium levels in the blood. On the flip side, insulin inhibits glycogenolysis, which stands for the breakdown of glycogen; and gluconeogenesis, which is glucose production from lactic acids and noncarbohydrate molecules. Finally, insulin inhibits lipolysis, the breakdown of lipids; and proteolysis, the breakdown of proteins.

Fuentes

  1. "Katzung & Trevor's Pharmacology Examination and Board Review,12th Edition" McGraw-Hill Education / Medical (2018)
  2. "Rang and Dale's Pharmacology" Elsevier (2019)
  3. "Goodman and Gilman's The Pharmacological Basis of Therapeutics, 13th Edition" McGraw-Hill Education / Medical (2017)
  4. "Insulin lispro: a fast-acting insulin analog" Am Fam Physician (1998)
  5. "Rapid-Acting and Human Insulins: Hexamer Dissociation Kinetics upon Dilution of the Pharmaceutical Formulation" Pharmaceutical Research (2017)
  6. "Short-acting insulin analogues versus regular human insulin for adults with type 1 diabetes mellitus" Cochrane Database of Systematic Reviews (2016)
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