Diabetes Flashcards
What is diabetes? What are the main types, risk factors, symptoms, and methods of diagnosis?
Diabetes is a chronic condition characterized by high blood sugar levels (hyperglycemia) due to problems with insulin production or action. The main types of diabetes are type 1 diabetes (T1DM) and type 2 diabetes (T2DM). Risk factors for diabetes include family history, obesity, sedentary lifestyle, high blood pressure, and certain ethnic backgrounds. Common symptoms of diabetes include excessive thirst, frequent urination, unexplained weight loss, fatigue, and blurred vision. Diagnosis involves blood tests such as fasting plasma glucose (FPG) and oral glucose tolerance test (OGTT).
What is the role of hormones in glucose homeostasis?
Hormones play a vital role in glucose homeostasis, regulating the levels of glucose in the blood. Insulin, released by the pancreas, promotes the uptake of glucose into cells, decreases glucose production in the liver, and promotes glucose storage as glycogen. Glucagon, also produced by the pancreas, stimulates the release of stored glucose from the liver. Other hormones involved in glucose regulation include cortisol, growth hormone, and epinephrine.
How does the pancreas regulate glucose homeostasis?
The pancreas plays a key role in glucose regulation. The beta cells of the pancreas secrete insulin in response to high blood glucose levels. Insulin promotes the uptake of glucose by cells, reducing blood glucose levels. The alpha cells of the pancreas produce glucagon, which stimulates the release of stored glucose from the liver when blood glucose levels are low. Together, insulin and glucagon help maintain the balance of glucose in the bloodstream.
What is the pathophysiology of type 1 diabetes (T1DM) and type 2 diabetes (T2DM)?
T1DM is an autoimmune disease where the immune system mistakenly attacks and destroys the beta cells of the pancreas, leading to a lack of insulin production. This results in uncontrolled high blood sugar levels. T2DM involves insulin resistance, where the body’s cells do not respond effectively to insulin. Over time, the pancreas may fail to produce enough insulin, leading to elevated blood sugar levels. T2DM is often associated with obesity, lifestyle factors, and genetic predisposition.
What are some common complications of diabetes?
Common complications of diabetes include cardiovascular disease, neuropathy (nerve damage), nephropathy (kidney disease), retinopathy (eye damage), foot problems, and increased risk of infections. Uncontrolled high blood sugar levels can damage blood vessels and organs, leading to these complications.
What are some glucose-lowering therapies for diabetes?
Glucose-lowering therapies for diabetes include lifestyle modifications (diet and exercise), oral medications (such as metformin, sulfonylureas), injectable medications (such as glucagon-like peptide-1 receptor agonists, insulin), and insulin pumps. The choice of therapy depends on the type and severity of diabetes, individual needs, and healthcare provider recommendations
How do insulins and new/emerging therapies replicate normal glucose homeostasis?
Insulin therapy is essential in diabetes management, especially for type 1 diabetes (T1DM) and some cases of type 2 diabetes (T2DM). Insulin is administered to replace or supplement the body’s natural insulin production, allowing glucose to enter cells and lowering blood sugar levels. New and emerging therapies aim to replicate normal glucose homeostasis by developing treatments that enhance insulin sensitivity, promote glucose uptake, regulate glucagon secretion, and target other aspects of glucose metabolism.
How can we delay type 1 diabetes (T1D) and restore glucose homeostasis?
Currently, there is no cure for T1D, but certain interventions may delay the onset or help manage the condition. Some approaches involve immune-based therapies to modulate the autoimmune response that leads to beta cell destruction. These therapies aim to preserve beta cell function and maintain glucose homeostasis. Research is ongoing in areas such as immunomodulatory drugs, antigen-specific therapies, and stem cell transplantation to restore or regenerate beta cells.
How do glucagon and insulin maintain glucose homeostasis in response to fed and fasted states?
Glucagon and insulin play critical roles in blood glucose homeostasis. Glucagon, produced by alpha cells, stimulates the liver to release stored glucose into the bloodstream during the fasted state. Insulin, produced by beta cells, promotes glucose uptake by cells, especially in muscle, adipose tissue, and the liver, and inhibits glucose production by the liver. In the fed state, insulin is released in response to high blood glucose levels, while glucagon is suppressed.
Which cells are responsible for insulin and glucagon production?
Beta cells in the pancreas produce insulin, while alpha cells produce glucagon. These hormone-producing cells are located in the Islets of Langerhans within the pancreas.
What are the steps involved in glucose-stimulated insulin secretion?
Glucose-stimulated insulin secretion involves several steps. When blood glucose levels rise, glucose is taken up by beta cells via glucose transporters. Glucose metabolism leads to the production of ATP, which triggers the closure of ATP-sensitive potassium channels, depolarizing the beta cell membrane. This depolarization opens voltage-gated calcium channels, allowing calcium influx. Increased calcium triggers insulin-containing vesicles to fuse with the cell membrane, leading to the release of insulin into the bloodstream.
What are the steps in the biosynthesis of insulin and C-peptide? What is the value of C-peptide as a marker of insulin secretion?
Insulin is synthesized as a preprohormone, which is then cleaved to form proinsulin. Proinsulin undergoes further enzymatic cleavage to produce insulin and C-peptide. C-peptide has value as a marker of insulin secretion because it is produced in equimolar amounts with insulin. C-peptide can be measured in blood to assess beta cell function independently of exogenous insulin.
Which tissues are insulin-sensitive, and how does glucose uptake occur in these tissues?
Insulin-sensitive tissues include muscle, adipose tissue, and the liver. Glucose uptake occurs via the facilitated glucose transporter called GLUT4. In response to insulin, GLUT4 is translocated from intracellular vesicles to the plasma membrane, allowing glucose to enter these tissues.
What is the role of incretin hormones (GLP-1, GIP) in augmenting insulin secretion?
Incretin hormones, such as glucagon-like peptide-1 (GLP-1) and gastric inhibitory polypeptide (GIP), are released from the intestines in response to nutrient intake. They enhance glucose-stimulated insulin secretion from beta cells, leading to increased insulin release. Incretin-based therapies, like GLP-1 receptor agonists, are used in the treatment of diabetes to augment insulin secretion.
What is the pathophysiology of type 1 diabetes (T1DM)?
T1DM is characterized by insulin deficiency due to the autoimmune destruction of beta cells in the pancreas. Most cases of T1DM result from an autoimmune response triggered by genetic and environmental factors. The progressive loss of beta cells leads to insufficient insulin production and the need for exogenous insulin administration.
