[1] Diabetes Mellitus Flashcards
What is diabetes mellitus?
A group of metabolic disorders in which there are high blood sugar levels over a prolonged period.
What are the different types of diabetes mellitus?
- Type 1
- Type 2
- Gestational diabetes
What is insulin?
The principle hormone that regulates the uptake of glucose from the blood into the most the cells of the body, especially the liver, adipose tissue, and muscle.
How does the body obtain glucose?
- Intestinal absorption of food
- Breakdown of glycogen
- Gluconeogenesis
How can insulin influence the glucose balance in the body?
- It can inhibit the process of gluconeogenesis or glycogenolysis
- It can stimulate the transport of glucose into muscle and fat cells
- It can stimulate the storage of glucose into muscle and fat ccells
What releases insulin?
Beta-cells in the islets of Langerhans in the pancreas
What is insulin released in response to?
Rising levels of blood glucose, typically after eating
How does lower glucose affect insulin release?
It reduces it
What is the role of glucagon?
It breaks down glycogen to glucose when there is low blood glucose
What will happen if the amount of insulin is insufficient, or if cells respond poorly to the effects of insulin due to insulin insensitivity?
Glucose will not be absorbed properly by body cells that require it, and will not be stored appropriately in the liver and muscles. The net effect is persistent high levels of blood glucose, poor protein synthesis, and other metabolic derangements such as acidosis
What happens when glucose concentrations in the blood remains high over time?
They kidneys will reach a threshold of reabsorption whereby they can no longer reabsorb all of the glucose, and some will be excreted into the urine, producing glycosuria
How does glycosuria cause lead to the symptoms of dehydration and thirst?
It increases the osmotic pressure in the urine, and inhibits reabsorption of water by the kidney, resulting in increased urine production and increased fluid loss. Lost blood volume will be replaced osmotically from water held in body cells and other body compartments, causing dehydration and increased thirst
What is the cause of T1DM?
Unknown, however it is believed to involve a combination of genetic and environmental factors. The genetic predisposition is associated wtih the genetic markers HLA DR3 and HLA DR4.
What is the underlying pathophysiological mechanism in T1DM?
Destruction of insulin-producing ß-cells of the pancreatic islets, leading to insulin deficiency
What % of cases of T1DM are immune mediated in nature?
90%
What happens in immune-mediated T1DM?
T-cell mediated autoimmune attack leads to a loss of ß-cells, and therefore insulin
What is T2DM characterised by?
Insulin resistance, which may be combined with reduced insulin secretion
What is the proportion of insulin resistance to ß-cell dysfunction in T2DM?
It varies between individuals, with some having primarily resistance and very little defect in insulin secretion, and some the opposite
What causes type 2 diabetes mellitus?
Predominantly lifestyle factors and genetics, but a number of other health problems or medications can predispose to diabetes
What lifestyle factors are known to be involved in the development of T2DM?
- Obesity and being overweight
- Lack of physical activity
- Poor diet, including high sugar, saturated fats, and trans fatty acid intake
- Stress
- Urbanisation
- Smoking
How are genes involved in the development of diabetes mellitus?
Most cases of T2DM involve many genes, with each being a small contributor to the increased probability of the development of T2DM
What health conditions are associated with an increased risk of T2DM?
- Acromegaly
- Cushing’s syndrome
- Hyperthyroidism
- Pheochromocytoma
- History of gestational diabetes
What medications can cause type 2 diabetes?
- Thiazides
- Glucocorticoids
- Beta blockers
- Atypical antipsychotics
- Statins
What are the symptoms of diabetes mellitus?
- Polydipsia
- Polyuria
- Fatigue
- Weight loss and loss of muscle bulk
- Thrush
- Blurred vision
- Slow healing of cuts and grazes