Classification and Causes of Diabetes Flashcards
What is the definition of diabetes mellitus?
A metabolic disorder of multiple aetiology characterised by chronic hyperglycaemia with disturbances of carbohydrate, protein and fat metabolism resulting from defects in insulin secretion, insulin action or both.
What is the WHO criteria for diabetes diagnosis?
Fasting plasma glucose of >7mmol/l
Random plasma glucose of >11.1mmol/l
One abnormal value diagnostic if symptomatic
Two abnormal values if asymptomatic
HbA1c 6.5% or 48mmol/mol
OGTT only required for diagnosis if IFG or GDM
Why is the WHO diagnostic cut off at 48mmol/l (6.5%)?
Because this is when prevalence of diabetic retinopathy starts to rise
How does diabetes present?
Hyperglycaemia - glycosuria - tired - weak - weight loss - difficulty concentrating - irritability - polydipsia - polyuria - thirs - dry mucous membranes - reduced skin turgor - postural hypotension Blurred vision Ketone production - nausea - vomiting - abdominal pain - heavy/rapid breathing - acetone breath - drowsiness - coma Complications - micro/macrovascular
Name the different types of diabetes.
MODY - maturity onset diabetes of the young T1DM T2DM Secondary DM LADA - non-insulin requiring T1DM
Briefly describe type 1 diabetes.
Pancreatic beta-cells are destroyed so they can’t produce insulin
- immune pathogenesis
Severe, absolute insulin deficiency
Briefly describe type 2 diabetes.
Combination of insulin resistance and therefore a relative insulin deficiency
- eventual loss of beta-cell function
What are the normal levels of ketones in the blood?
Normal <0.6mmol/l
Moderately elevated 0.6 to 1.5mmol/l
Very elevated >1.5mmol/l
What is the purpose of measuring islet autoantibodies?
Markers of autoimmune process associated with type 1 diabetes.
- glutamic acid decarboxylase and insulinoma-associated antigen 2
Present in 80% of T1DM
For patients with T2DM, presence of antibodies indicates faster progression to insulin
What is the purpose of measuring c-peptide?
Secreted in equimolar concentrations to insulin
- marker of endogenous insulin
What is the pathogenesis of T1DM?
Chronic, progressive metabolic disorder characterised by hyperglycaemia and the absence of insulin secretion
Results from autoimmune destruction of the insulin-producing beta-cells of the islets of langerhans
Occurs in genetically susceptible subjects and is probably triggered by environmental agents
Name some possible precipitating causes of T1DM.
Viral infections Immunisations Diet - cows milk at an early age Higher socioeconomic status Obesity Vitmain D deficiency Perinatal factors - maternal age, history of pre-eclampsia, neonatal jaundice and low birth weight (reduced risk)
What is the pathogenesis of T2DM?
Chronic, progressive metabolic disorder characterised by hyperglycaemia, insulin resistance and relative insulin deficiency
Prevalence rises with obesity
Arises through a combination of genes and environmental factors
What is MODY?
Maturity onset diabetes of the young
- single gene (monogenic) mutation
- autosomal dominant
What are the three main featurs of MODY?
Often <25 years onset
Runs in families from one generation to the next
Managed by diet, oral hypoglycaemic agents and sometimes insulin
