[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
How do people with type 1 diabetes mellitus sometimes present?
With diabetic ketoacidosis
Describe the onset of T1DM
The symptoms can develop very quickly, over a few days or weeks, especially in children. In adults, they are more likely to take a few months to develop
Describe the onset of T2DM
They develop slowly, and don’t necessarily make the person feel unwell, so the person may not realise they have it for a long time
What is a diagnosis of diabetes mellitus made on?
The basis of a high plasma glucose
What are the diagnostic criteria for diabetes mellitus?
- Random venous plasma glucose >11.1mmol/L
- Fasting plasma glucose concentration >7.0mmol/L (whole blood >6.1mmol/L)
When can a diagnosis of diabetes not be made on the basis of a single glucose measurement?
When there are no symptoms, as is often the case in T2DM
What confirms a diagnosis of diabetes when there is a single reading of raised plasma glucose but no symptoms?
At least 1 additional glucose test result on another day with a value in the diabetic range
Why is it important to get at least two readings of raised plasma glucose when diagnosing diabetes with no symptoms?
Because a diagnosis of diabetes has important legal and medical implications for the patient
What should a person newly diagnosed with type 1 diabetes develop?
An individual care plan
Who does the individual care plan in type 1 diabetes need to be jointly agreed between?
The patient and the doctor
How should the individual care plan for a patient with type 1 diabetes develop over time?
It should be reviewed and modified annually
What should be taken into account when reviewing and modifying the individual care plan in diabetes mellitus?
Changes in the person’s wishes, circumstances, and medical findings
What should the individual care plan in type 1 diabetes involve?
- Education, involving nutritional advice
- Insulin therapy
- Self-monitoring
- Hypoglycaemia avoidance and monitoring
- Other elements
Why is it important to offer dietary advice to those with type 1 diabetes mellitus?
So they can adequately manage their blood glucose, as well as their weight and cardiovascular risk
What programmes should be made available to patients with type 1 diabetes, regarding dietary management?
Programmes that will allow them to make optimal choices about the variety of foods they eat, and change their insulin dose to mimic as far as possible the physiological response
What should any nutritional information given to a patient with T1DM take into account?
- Any personal and cultural needs
- Associated features of diabetes, such as obesity or being underweight, hypertension, and renal failure
How often should HbA1c levels be monitored in adults with type 1 diabetes?
Every 3-6 months
You should consider measuring more often if the glucose control is suspected to be changing rapidly
What is the target HbA1c in diabetes mellitus?
6.5%, however an individualised target can be made
Why is a target HbA1c of 6.5% given?
To minimise the risk of long-term vascular complications
What might an individualised HbA1c target take into account?
- Daily activities
- Likelihood of complications
- Co-morbidities
- Occupation
- History of hypoglycaemia
What blood glucose level should be aimed for in T1DM?
Fasting plasma glucose level of 5-7mmol/L on walking, and a plasma glucose of 4-7mmol/L before meals at other times of the day
How often should patients with T1DM self-monitor their glucose levels?
At least 4 times a day, including before each meal and before bed.
In some scenarios, the patient should monitor their glucose up to 10 times a day
Give 3 examples of when a person might need to self-monitor their glucose levels up to 10 times a day
- If they are ill
- If there is an increased frequency of hypoglycaemic episodes
- If they are undertaking strenuous exercise
Is continuous blood glucose monitored used in T1DM?
It is not routinely offered, however is an option in certain circumstances
When might continuous blood glucose monitoring be used in T1DM?
- More than one episode per year of severe hypoglycaemia with no obvious cause
- Complete loss of awareness of hypoglycaemia
- Extreme fear of hypoglycaemia
What kind of hormone in insulin?
Polypeptide
What does insulin consist of structurally?
Two peptide chains that are connected by disulphide bonds
How is insulin produced?
It is synthesised as the pre-cursor proinsulin, and then undergoes proteolytic cleavage to form insulin and C-peptide, both of which are secreted from the ß-cells of the pancreas
What is the secretion of insulin controlled by?
Plasma glucose levels
Why is exogenous insulin administered in T1DM?
To replace absent insulin secretion
What are the 6 main categories of exogenous insulin?
- Ultrafast acting
- Rapid acting
- Short acting
- Intermediate acting
- Long acting
- Very long acting
Give an example of ultrafast acting insulin
FiAsp
Give 3 examples of rapid acting insulins
- Humalog
- Novorapid
- Apidra
What is the onset of action of short-acting insulin?
5-15 minutes
When does the action of rapid acting insulin peak?
At about 60 minutes
What is the duration of action of rapid acting insulin?
4-6 hours
When is rapid acting insulin injected?
Just before eating
Give two examples of short acting insulins
- Actrapid
- Humulin S
What is the onset of action of short acting insulins?
30-60 minutes
When does the action of short acting insulin peak?
2-3 hours
What is the duration of action of short acting insulin?
8-10 hours
When is short acting insulin injected?
15-30 minutes before eating
What is the problem with short acting insulin?
Because it is only injected 15-30 minutes before eating, but doesn’t peak for 2-3 hours, the person will have very high glucose after the meal, which can increase the risk of long-term complications over time
Give 3 examples of intermediate acting insulins
- Insulatard
- Humulin I
- Insuman Basal
What is the onset of action of intermediate acting insulin?
Slower 2-4 hours
When does the action of intermediate acting insulin peak?
4-8 hours
What is the duration of action of intermediate acting insulins?
12-20 hours
What is the purpose of intermediate acting insulin?
They cover between meals and overnight
Give an example of a long acting insulin
Glargine
What is the onset of action of glargine?
2-6 hours
What is the duration of action of glargine?
24 hours
Give an example of a very long acting insulin
Degludec
What is the duration of action of degludec?
50+ hours
What are the adverse effects of insulin?
- Hypoglycaemia
- Weight gain
- Local injection site reactions
- Lipodystrophy
How can the risk of lipodystrophy with insulin injections be minimised?
By changing the injection site
How is human insulin produced?
By recombinant DNA technology, using strains of E. Coli or yeast that are genetically modified to contain the gene for human insulin
What produces insulin with different pharmacokinetic properties?
Modification of the amino acid sequence of human insulin
What factors can affect the onset and duration of various insulin preparations?
- Dose
- Injection site
- Temperature
- Blood supply
- Physical activity
Why can insulin not be taken orally?
As it is a polypeptide, and therefore would be degenerated in the GI tract
How is insulin administered?
Normally subcutaneously, but can be given IV in hyperglycaemic emergencies
What are insulin pumps also known as?
Subcutaneous insulin infusion
How do insulin pumps deliver insulin?
They deliver a basal rate of insulin
Does the patient ever need to inject insulin if they have an insulin pump?
Yes, they inject a bolus of insulin to cover mealtimes
What is the advantage of insulin pumps?
They are more convenient for the patient, as they eliminate the need for multiple daily injections