Diabetes Flashcards
What is the main cause of type 1 diabetes?
-Autoimmune progressive B-cell destruction via autoantibodies, macrophages and killer lymphocytes
Describe Diabetes Mellitus
Condition where blood glucose levels can become elevated, which over years leads to damage to the small and large blood vessels causing premature death from cardiac diseases
Where is insulin produced and secreted?
In the b-cells in the islets of langerhans in the pancreas
What is the triad of symptoms for type 1 diabetes and why do these symptoms occur?
Polyuria - Increased urination - as blood glucose levels rise they surpass the renal threshold meaning that more glucose is excreted in the urine. As levels of glucose in the urine rise, water is drawn in to the tubules and is thus not reabsorbed, increasing the amount of urine being formed
Polydipsia - increased thirst as a result of water loss due to polyuria
Weight Loss - as there is an absolute deficiency of insulin, fat mobilistation occurs, followed by lipolysis. Proteolysis also occurs. This occurs so that the stored energy within lipid and protein can be used in cells
Why are people with diabetes susceptible to recurrent urogenital infections, particularly thrush?
High levels of glucose within the blood means bacteria can thrive
Why do people with diabetes experience tiredness, weakness and lethargy?
Due to inadequate energy utilisation
Why do people with diabetes experience blurred vision during a hyperglycaemic episode?
Hyperglycaemia causes swelling in the lens of the eye
In late presentation of Type 1 Diabetes, how may a patient present and why?
- Ketoacidosis
- Nausea/Vomiting
- Confusion
- Slurred speech
- Dizziness
- Acetone on breath
- Ketoacidosis occurs due to fat mobilisation and lipolysis. Glucose utilisation is inadequate due to no insulin, thus fat mobilisation occurs. Lipolysis breaks the fats down into glycerol and FAs. FAs undergo B-oxidation into Acetyl CoA. This Acetyl Co A is then converted into an excessive amount of ketones. Accumulation of ketones lowers the pH of the blood leading to ketoacidosis
At what age do Type 1 diabetes patients usually present?
Usually before the age of 30 but not always.
What is the treatment for Type 1 Diabetes?
- Exogenous insulin via subcutaneous injection
- Patient must be educated into appropriate times and doses
- Appropriate dietary management and exercise
What causes type 2 diabetes?
Insulin resistance leading to insulin deficiency
Why does insulin resistance develop?
- The cells become non-responsive and down-regulate insulin receptors due to the continually high circulating levels of glucose
- Also the high circulating free FAs interferes with insulin sensitivity
- Associated with obesity
How old do type 2 patients usually present?
Usually above 40 years, however it is becoming increasingly common in children
Why do people with type 2 diabetes not experience weight loss and ketoacidosis?
-There is an insulin resistance/deficiency not an absolute lack of insulin. -The body doesn’t enter the starvation catabolic state and thus fat metabolism, lipolysis and proteolysis does not occur. Therefore there is no weightloss. Ketoacidosis does not occur as there is no increase in free FAs so no ketones are produced
What is the treatment of type 2 diabetes?
- 3 levels of treatment
1) Diet and lifestyle changes
2) Non-insulin therapies, eg sulphonylureas (increase insulin from remaining B cells and reduce gluconeogenesis) and metformin (reduces gluconeogenesis)
3) insulin (rare)
What are the acute complications of hyperglycaemia?
- Massive metabolic decompensation
- Diabetic Ketoacidosis in type 1
- Hyper-osmolar non-ketotic syndrome in type 2
What is hyper-osmolar non-ketotic syndrome?
A relative insulin deficiency leads to a serum glucose and a resulting increase in serum osmolarity. This leads to polyuria which, in turn, leads to volume depletion and hemoconcentration that causes a further increase in blood glucose level .Hyperglycemia and hyperosmolarity result in an osmotic diuresis and an osmotic shift of fluid to the intravascular space, resulting in further intracellular dehydration. This diuresis also leads to loss of electrolytes, such as sodium and potassium
What are the acute complications of hypodlycaemia?
Diabetic coma due to lack of insulin to the brain
What macrovascular chronic complications can occur in diabetes?
- Stroke
- MI
- Gangrene
What microvascular chronic complications can arise in diabetes?
- Retinopathy-> Very small blood vessels in the eye get damaged by consistent high levels of glucose, causing leakage of protein exudate onto retina potentially leading to blindness. Changes in osmotic pressure due to glucose accumulation can cause blurred vision
- Nephropathy -> Damage is sustained to the small capillaries of the glomerulus due to chronic high glucose levels, potentially leading to renal failure
- Neuropathy -> damage to peripheral nerves by chronic high glucose leads to loss of feeling at the periphery. Can cause diabetic foot ulcers; skin more prone to damage (dehydrated) and patient lost sensation in the foot. Also high glucose levels in the blood result in bacteria being able to thrive resulting in an ulcer
Why can insulin resistance lead to insulin deficiency in T2 diabetes?
-Amyloid deposits begin to form in the islet cells causing B cell failure
Define ketoacidosis
-State of absolute insulin deficiency aggravated by ensuing hyperglycaemia, dehydration and acidosis
How does ketoacidosis develop?
- Insulin defeciency leads to cells not being able to utilise glucose as a source of fuel
- Patient become hyperglycaemic with polyuria and glycosuria leading to dehydration and decreased blood volume
- Body enters catabolic state and begins fat mobilisation and lipolysis
- High levels of free FA are converted into acetyl coA and then ketones (so brain can use them and also because the lack of insulin means lyase is not inhibited)
- Excessive ketone formation surpasses renal threshold and effects buffering capacity of the blood leading to acidosis
What is the cause of hypoglycaemia in diabetics?
-Administration of too much insulin
