Type 1 Diabetes Flashcards
Which countries have a particularly high prevalence of type 1 diabetes?
Kuwait and UAE
What is the UK prevalence of type 1 diabetes?
0.3-0.4%
When are most cases of T1DM diagnosed? When is there a secondary peak?
Most cases are diagnosed in adolescence, with a secondary peak in the late 30s
What is the simplest explanation of the cause of T1DM?
Environmental trigger in a genetically susceptible individual
T1DM is mediated by what kind of process? Where does this occur?
An autoimmune processes occurring within the pancreatic beta cells
Pancreatic beta cells are found where in the pancreas?
Islet’s of Langerhan’s
Where in the Islet are beta cells seen? What do they produce?
In the middle of the Islet, they produce insulin
Where in the Islet are alpha cells seen? What do they produce?
In the periphery of the Islet, they produce glucagon
What type of hypersensitivity reaction is T1DM? What mediates this?
Type IV- cell mediated (T cells)
In T1DM, the T cells attack where?
The pancreatic beta cells
What is the effect of a lack of insulin?
Glucose builds up in the blood because it cannot enter cells
T1DM occurs mainly because of a genetic abnormality involving what system?
HLA genes
The HLA system is made up of a group of genes on which chromosome? What is this group known as?
MHC group on chromosome 6
What is the MHC protein important for?
Helping the immune system to recognise foreign antigens, and for self-tolerance
HLA represents around 50% of the familial risk of T1DM. What are the highest risk genotypes?
HLA-DR3-DQ2 and HLA-DR4-DQ8
How likely is it that someone with T1DM will have one or both of the implicated HLA genes?
95% of those diagnosed < 30
If you have one of the HLA genes implicated in diabetes, does this mean you definitely have the condition?
No, many people will have this genotype without having diabetes
What are some environmental factors which may contribute to the development of T1DM?
Seasonality, timing of birth, viral infection, maternal factors, weight gain
There are many diagnoses of T1DM in which month?
January
How much of the pancreatic beta cells can be destroyed before symptoms show?
Most destruction presents early in life, but sometimes up to 90% can be destroyed before any symptoms show
Tests for T1DM have to be taken into consideration with what else?
The presence of symptoms!
If a patient has tested positive for diabetes but doesn’t have any symptoms what should you do?
Run repeat tests to ensure it wasn’t a coincidence
Often T1DM can be diagnosed without any clinical tests, what presentation can commonly be a first indicator of diabetes?
DKA
If in doubt of a diagnosis of T1DM, what are some tests you could do?
Anti-GAD/Anti-islet cell antibodies, C-peptide
What is the concordance of T1DM in monozygotic twins?
30-50%
If a patients mother has T1DM, what will be their chance of getting it?
3%
If a patients father has T1DM, what will be their chance of getting it?
8%
If both of a patient’s parents have T1DM, what will be their chance of getting it?
30%
What are 4 antibodies which may be seen in T1DM?
Anti- GAD // Anti-IA-2 // Anti-IAA // Anti-ZnT8
Which autoantibody in T1DM has the highest % at diagnosis?
Anti-GAD
Which T1DM autoantibodies seem to increase with age?
Anti-GAD and Anti-ZnT8
Which T1DM autoantibody decreases with age?
Anti-IA-2
Which T1DM autoantibody is better in children?
Anti-IAA
Which T1DM autoantibody is more seen in males?
Anti-IA-2
Which T1DM autoantibody has a stronger correlation with females < 10?
Anti-GAD
Ketones above what is a significant amount?
> 1.5
Ketones above what is classed as DKA?
> 3
What are some other autoimmune diseases which are associated with T1DM?
Thyroid disease // Pernicious anaemia // Addison’s // IgA deficiency // Coeliac disease
If you are testing for T1DM antibodies, what else should you test for?
Anti-TTG antibodies for Coeliac (also maybe duodenal biopsy)
What are some biochemical changes associated with Coeliac disease?
Anaemia, decreased albumin, decreased Ca++
What weight will patients who present acutely with T1DM be?
Low weight- thin
What is usually the onset of T1DM?
Acute onset of severe symptoms
What is the classic triad of symptoms in T1DM?
Polyuria, polydipsia, weight loss
Polyuria can present as what in young children?
Enuresis (bed wetting)
As well as the classic triad, what are some other symptoms of T1DM?
Fatigue, blurred vision, candida infections, ketoacidosis +/- metabolic acidosis
Will there be any evidence of microvascular disease in a new T1DM patient?
No
Why do weight loss and hunger occur as symptoms of T1DM?
Because of the lack of insulin, glucose cannot get into cells, therefore cells are starved of energy and start to break down. Adipose tissue undergoes lipolysis and muscle tissue undergoes protein breakdown. These both lead to weight loss and hunger.
Why do patients with T1DM present with polyuria/glucosuria? Why do they become dehydrated and thirsty?
Because there is a lot of glucose in the blood, this gets excreted by the kidneys. Since glucose is osmotically active, water tends to follow it which results in polyuria and glycosuria. Because of so much urination, patients will become dehydrated and thirsty.
