Diagnosis of Diabetes Flashcards
(26 cards)
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 the diagnosis of diabetes?
•Fasting plasma glucose ≥7.0mmol/l
•Random plasma glucose ≥11.1mmol/l
•One abnormal value is diagnostic if symptomatic
•Two abnormal values is diagnostic if asymptomatic
•HbA1c 6.5% or 48mmol/mol
•
When is an oral glucose tolerance test required?
- Gestational diabetes mellitus
* Impaired fasting glycaemia
What are the diagnostic aids for diabetes?
- Ketone testing ± bicarbonate
- Pancreatic autoantibodies
- C-peptide testing
What is a normal blood ketone reading?
<0.6mmol/l
Explain what is needed to be in diabetic ketoacidosis
- Hyperglycaemia (>11.1mmol/l or known diabetes)
- Hyperketonaemia (≥3.0mmol/L on fingerprick) or ketonuria (more than 2+ on urine dipstick testing)
- Metabolic acidosis (venous bicarbonate <15 mmol/L and/or venous pH <7.3)
What are the islet autoantibodies?
- Markers of autoimmune process associated with T1DM
- Glutamic acid decarboxylase (GAD)
- Insulinoma-associated antigen 2
When is the most useful time to test for islet autoantibodies?
3-5 years from diagnosis
What is C peptide?
- Secreted in equimolar concentrations to insulin
- Useful marker of endogenous insulin secretion
- Can be measured in blood or urine
When is the most useful time to measure C-peptide?
3-5 years from diagnosis
What does type 1 diabetes result from?
Autoimmune destruction of the insulin producing beta cells in the islets of langerhands
What are the stages to type 1 diabetes?
- Genetic risk
- Immune activation
- Immune response - development of single autoantibody
- Stage 1 - Normal blood sugar, ≥2 autoantibodies, start of T1DM
- Stage 2 - Abnormal blood sugar, ≥2 autoantibodies
- Stage 3 - clinical diagnosis, ≥2 autoantibodies
- Stage 4 - long-standing T1DM
Explain the pathogenesis of T1DM
•Genetic •Environmental: - viral infections - immunisation - diet - higher socioeconomic status. - obesity - vitamin D deficiency - Perinatal factors
Age of presentation in Type 1 vs Type 2 Diabetes mellitus
- T1 <40
* T2 >50
Weigh in Type 1 vs Type 2 Diabetes mellitus
- T1: Normal
* T2: obese or overweight
Ethnicity risk in Type 1 vs Type 2 Diabetes mellitus
- T1: Northern European
* T2: Asian, African, Polynesian and American Indian
Family History of diabetes in Type 1 vs Type 2 Diabetes mellitus
- T1: Uncommon
* T2: Common
Pathogenesis in Type 1 vs Type 2 Diabetes mellitus
- T1: Autoimmune
* T2: no immune
Ketonuria/ketonemia/acidosis in Type 1 vs Type 2 Diabetes mellitus
- T1: common
* T2: uncommon
Clinical in Type 1 vs Type 2 Diabetes mellitus
- T1: insulin deficiency ± Ketoacidosis, dependent on insulin for survival, other autoimmune disease common
- T2: Partial insulin deficiency at presentation ± hyperosmolar state, may need insulin, other autoimmune uncommon
Biochemistry/immunology in Type 1 vs Type 2 Diabetes mellitus
- Type 1: C peptide inappropriate or negative (<200), usually GAD Ab positive
- Type 2: C peptide elevated (>900) GAD Ab usually negative
What causes pancreatic diabetes?
- Pancreactectomy
- Pancreatitis
- Haemochromatosis (liver disease, cardiomyopathy, pituitary disease)
- Carcinoma
- Cystic fibrosis
Why are risk of hypos higher in pancreatic diabetes?
Because there is a loss of alpha cells that produce glucagon
What are the features of pancreatic diabetes?
- History of cause
- Exocrine dysfunction
- May have ketones and may be acidotic
- C peptide low but often detectable
- Pancreatic antibodies negative
- May require imaging
- Managed by Sulfonylurea
