10 Questions
What are the two main types of diabetes mentioned in the text and their former names?
Type 1 diabetes (formerly insulin-dependent diabetes mellitus), Type 2 diabetes (formerly non– insulin-dependent diabetes mellitus)
What is the polypeptide hormone consisting of two peptide chains that are connected by disulfide bonds?
Insulin
What is synthesized as a precursor that undergoes proteolytic cleavage to form insulin and C-peptide?
Proinsulin
What provides a better index of insulin levels than plasma insulin levels?
C-peptide
What triggers insulin secretion most often?
Increased blood glucose
Explain the difference between Type 1 and Type 2 diabetes in terms of age of onset, nutritional status at time of onset, and prevalence.
Type 1 diabetes usually occurs during childhood or puberty, while Type 2 diabetes commonly develops in individuals over age 35. Type 1 diabetes is commonly associated with undernourishment, whereas Type 2 diabetes may be linked to obesity. Type 1 diabetes accounts for 5-10% of diagnosed diabetics, while Type 2 diabetes accounts for 90-95% of diagnosed diabetics.
Describe the process of insulin production and secretion by the β cells of the pancreas.
Insulin is synthesized as a precursor (proinsulin) that undergoes proteolytic cleavage to form insulin and C-peptide, both of which are secreted by the β cells of the pancreas. Insulin secretion is regulated by blood glucose levels, certain amino acids, other hormones, and autonomic mediators, with increased blood glucose often triggering secretion.
What are the genetic predispositions and defects associated with Type 1 and Type 2 diabetes, respectively?
Type 1 diabetes is associated with a very strong genetic predisposition, as cells are destroyed, eliminating the production of insulin. Type 2 diabetes is characterized by the inability of cells to produce appropriate quantities of insulin, insulin resistance, and other defects, often linked to obesity.
Explain the structure and synthesis of insulin and C-peptide in the context of insulin and insulin analogs.
Insulin is a polypeptide hormone consisting of two peptide chains connected by disulfide bonds. It is synthesized as a precursor (proinsulin) that undergoes proteolytic cleavage to form insulin and C-peptide, both of which are secreted by the β cells of the pancreas. Measurement of C-peptide provides a better index of insulin levels than plasma insulin levels.
Discuss the factors that regulate insulin secretion and the primary trigger for insulin secretion.
Insulin secretion is regulated by blood glucose levels, certain amino acids, other hormones, and autonomic mediators. The primary trigger for insulin secretion is increased blood glucose, which is taken up by the glucose transporter into the β cells of the pancreas.
Test your knowledge about different types of diabetes, age of onset, nutritional status at the time of onset, prevalence, genetic predisposition, and defects or deficiencies.
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