Diabetes Flashcards
(47 cards)
What is diabetes characterised by?
it is a group of disorders characterised by:
hyperglycaemia - high blood glucose
caused by a lack of insulin of reduction in action of insulin
Label the components of the pancreas
What are the different pancreatic islet cells?
What do they secrete?
- alpha cells - secrete glucagon
- beta cells - secrete insulin
- delta cells - secrete somatostatin
- F cells - secrete pancreatic polypeptide
What can proinsulin be converted into?
What are the steps involved in these processes?
insulin:
- prohormone convertase 3 coverts proinsulin to split (32-33) proinsulin
- carboxypeptidase converts this into Des (31, 32) proinsulin
- this is converted into insulin
C peptide:
- prohormone convertase 2 converts proinsulin to split (65,66) proinsulin
- carboxypeptidase converts this into Des (64, 65) proinsulin
- this is converted into C peptide
What is the structure of insulin like?
it is a soluble protein
it has 2 chains - an alpha chain and a beta chain
Where is insulin synthesised?
insulin is synthesised in the beta cells of the pancreas
insulin mRNA is translated as a single chain precursor - preproinsulin
removal of the signal peptide during insertion into the endoplasmic reticulum generates proinsulin
What are the general actions of insulin?
- metabolic
- paracrine effects
- vascular, fibrinolysis, growth and cancer
What are the 4 factors involved in diabetes diagnosis?
fasting glucose >/= 7 mmol / litre
random plasma glucose >/= 11.1 mmol / litre
two hours reading post OGTT >/= 11.1 mmol / litre
HbA1c >/= 48 mmol/mol
What is normal fasting glucose?
How does this change in the oral glucose tolerance test (OGTT)?
normal fasting glucose is >/= 7 mmol / litre
patient ingests 75g of anhydrous glucose
after 2 hours their glucose reading >/= 11.1 mmol / litre
In the oral glucose tolerance test (OGTT) what would be an impaired fasting glucose and impaired glucose tolerance?
impaired fasting glucose:
- 6.1 - 6.9 mmol / litre
impaired glucose tolerance:
- glucose >/= 7.8
- glucose < 11.1 mmol / litre
What is meant by “pre-diabetes”?
How is it diagnosed?
when blood glucose levels are too high, but not high enough to be called diabetes
people with prediabetes are at a higher risk of developing type 2 diabetes
it is diagnosed using the HbA1c criteria
How can the HbA1c criteria be used to distinguish between diabetes and prediabetes?
it reflects the average plasma glucose over the previous 8 - 12 weeks
>/= 48 mmol/mol in diabetes
>/= 41 and < 48 mmol/mol in prediabetes
How is diabetes classified?
- type 1 diabetes
- type 2 diabetes
- gestational diabetes
- specific types
genetics, endocrinopathies, disease of the exocrine pancreas
What causes type 1 diabetes?
autoimmune destruction of insulin producing beta cells in the islet of langerhans
What types of people tend to be affected by type 1 diabetes?
it can occur at any age but peaks around puberty
it has equal sex incidence but after 15 years of age, there is a two fold increased risk in males
incidence has increased by 3-4% in the last few years
What is involved in the pathophysiology of type 1 diabetes?
genetics of T1DM:
- HLA class II
- DR4 - DQ8
- DR3 - DQ2
- exposed / trigger to environmental factors
- autoimmunity
What are the risk factors for type 1 diabetes mellitus?
- family history (genetic susceptibility)
- perinatal factors - low birth weight
- viral infections
- diet - cows milk
What are the 3 stages invovled in the development of type 1 diabetes?
stage 1:
- trigger of beta cell immunity but no symptoms of diabetes
stage 2:
- loss of beta cell secretory function and development of antibodies and slight glucose elevation
- no symptoms
stage 3:
- loss of beta cell capacity
- symptoms present
What autoantibodies are present as a result of humoral autoimmunity?
- insulin autoantibodies
- glutamic acid decarboxylase autoantibodies (GAD)
- islet antigen-2 autoantibodies (IA-2)
- ZnT8 transporter autoantibodies
What is involved in the presentation of type 1 diabetes?
- rapid onset - often a few weeks
- weight loss + osmotic symptoms + low energy
- abdominal pain
- often slim
- present as diabetes ketoacidosis
What is involved in the management of type 1 diabetes mellitus?
always need insulin at the start of diagnosis
there is no role of an oral agent as the body is unable to produce any insulin
What is the presentation of type 2 diabetes mellitus often like?
- often overweight
- symptoms present over few months
- minimal weight loss (unless left for long period)
- can present with complications such as vision loss, foot ulcers or fungal infection
- can present in state of hyperosmolar hyperglycaemia state (HHS) or HONK
What is indicated by the lines on this graph?
