Type 1 Diabetes Flashcards
What causes type 1 diabetes?
What does type 1 diabetes result in?
An autoimmune condition in which insulin-producing beta-cells in the pancreas are attacked and destroyed by the immune system
The result is a partial or complete deficiency of insulin production, which results in hyperglycaemia
The resultant hyperglycaemia requires life-long insulin treatment
What are the different types of diabetes?
Type 1 Diabetes Type 2 Diabetes Hybrid forms (starts in adulthood but presents like type 1) Other Unclassified During pregnancy
What is LADA?
Latent autoimmune diabetes in adults
Autoimmune diabetes leading to insulin deficiency in, presenting in adults
Can T2DM present in childhood?
Can diabetic ketoacidosis be a feature of T2DM?
Yes
Yes - although more typical in type 1
What event might diabetes present after?
Following pancreatic damage or other endocrine disease
What challenges might clinicians face when trying to diagnose type 1 and type 2 diabetes?
Clinicians are faced with a challenge, trying to differentiate adult-onset type 1 diabetes from the much large numbers of cases of type 2 diabetes
What are the stages of development of type 1 diabetes?
Genetic predisposition
Potential precipitating event (a triggering event)
Overt immunological abnormalities; normal insulin release
Progressive loss of insulin release; glucose normal
Overt diabetes; C-peptide present
No C-peptide present
What do we measure when looking at beta cell function?
C-peptide cleaved from pro-insulin (C-peptide more stable in the blood)
Pro-Insulin is cleaved to make insulin and c peptide in a 1:1 ration
Why is the immune basis of T1DM important?
Increased prevalence of other autoimmune disease
Risk of autoimmunity in relatives
More complete destruction of B-cells
Auto antibodies can be useful clinically
Immune modulation offers the possibility of novel treatments (not there yet)
Summarise immunology of T1DM?
Primary step is the presentation (by APC) of auto-antigen to autoreactive CD4+ T lymphocytes
CD4+ cells activate CD8+ T lymphocytes (cytotoxic)
CD8+ cells travel to islets and lyse beta-cells
expressing auto-antigen
Exacerbated by release of pro-inflammatory cytokines
Underpinned also, by defects in regulatory T-cells that fail to supress autoimmunity
Are all the beta cells destroyed in T1DM?
Not always, some beta cells escape the immune response
Some people with type 1 diabetes continue to produce small amounts of insulin and have C-peptide
Not enough to negate the need for insulin therapy
What is HLA?
What HLA is associated with diabetes?
Human Leukocyte antigen
HLA-DR = If you have these polymorphisms you are 6x more likely to develop T1DM
What are the environmental factors involved with T1DM?
Multiple factors implicated, but causality has not been established
Enteroviral infections
Cow’s milk protein exposure
Seasonal variation
Changes in microbiota
When are auto-antibodies detectable?
Are auto-antibodies needed for diagnosis?
Detectable in the sera (serums) of people with Type 1 diabetes at diagnosis
Not generally needed for diagnosis in most cases
When are pancreatic auto-antibodies made?
Made when the beta cells content is exposed
What are the different types of pancreatic auto-antibodies ?
Insulin autoantibodies (IAA) Glutamic acid decarboxylase (GADA) – widespread neurotransmitter (prevents GABA production in pancreatic cell) Insulinoma-associated-2 autoantibodies (IA-2A) Zinc-transporter 8 (ZnT8) autoantibody
What are symptoms of T1DM?
Excessive urination (polyuria) Nocturia Excessive thirst (polydipsia) Blurring of vision Recurrent infections eg thrush Weight loss Fatigue
Why does T1DM lead to blurry vision?
Glucose goes into eyeball
Causes osmotic change in lens
What are the signs of T1DM?
Dehydration Cachexia (wasting) Hyperventilation (resp. compensation) Smell of ketones Glycosuria Ketonuria
What are the 4 Ts of T1DM?
Toilet
Thirsty
Tired
Thinner
What is the mechanism of ketone body production in T1DM?
- Insulin deficiency- less suppression of fatty acyl-coa metabolism (Also stimulated by glucagon)
- NEFAs enter liver
- Fatty acyl-coa converts NEFA to Acetyl COA -> acetoacetate -> acetone + 3OH-B
- These are ketone bodies and are acidic so bad lead to diabetic ketoacidosis
What happens with insulin deficiency?
Proteolysis (inc. AAs)
Hepatic glucose output (inc. glucose)
Lipolysis (inc. Glycine and NEFA
What are the aims of treatment in type 1 diabetes?
Maintain glucose levels without excessive hypoglycaemia
Restore a close to physiological insulin profile
Prevent acute metabolic decompensation
Prevent microvascular and macrovascular complications