Investigations Flashcards
How would you investigate someone with suspected diabetes mellitus?
- Diagnostic fasting glucose levels - ≥ 7.0 mmol/l
- Random glucose testing - ≥ 11.1 mmol/l
- 2hrs after glucose - ≥11.1 mmol/l
- HbA1c - ≥ 48 mmol/l
How is diabetes diagnosed?
ONE diagnostic lab glucose plus symptoms
TWO diagnostic lab glucose or HbA1c without symptoms
If testing random glucose, what is diagnostic of diabetes?
Value of >/= 11.1 mmol/L on 2 seperate occasions, or on one occasion with symptoms
If testing fasting glucose, what is diagnostic of diabetes?
Value of >/= 7.0 mmol/L on two seperate occasions
OR
>/=7.0 mmol/L plus a positive glucose tolerance test (>/= 11.1 mmol/L)
OR
Positive once plus symptoms
If testing glucose tolerance, what is diagnostic of diabetes?
Value of >/= 11.1 mmol/L on two seperate occasions
OR
>/=7.0 mmol/L plus a positive glucose tolerance test (>/= 11.1 mmol/L)
OR
Positive once plus symptoms
If testing HbA1c, what is diagnostic of diabetes?
Value >/= 48 mmol/L
What is HbA1c?
Glycosylated Haemoglobin - Results in formation of a covalent bond between the glucose molecule and the terminal valine of the β chain of the haemoglobin molecule.
Gives indication of blood glucose levels over last 2-3 months.
Integrated measure of an individual’s prevailing blood glucose concentration over several weeks.
When would you not use HbA1c for diagnosis of diabetes?
- Pregnancy
- Children
- Type I diabetes
- Haemoglobinopathies
- Renal Failure
- HIV infection
- Corticosteroid use
In an adult, what would you challaenge them with as part of the glucose tolerance test?
75g glucose in 300 ml water
For a glucose tolerance test, when are measurements taken?
Fasting and 120 minute sample
What is classed as impaired glucose tolerance?
- <7.0 mmol/L fasting
- 7.8-11.0 post challenge (OGTT)
What is classed as impaired fasting glucose?
Fasting plasma glucose between 6.1 and 6.9 mmol/L
Besides glucose testing, what other tests might you do in someone with suspected diabetes?
Look for complications
- Fundoscopy
- U+E’s and Dipstick
- Neurovascular examination
What are impaired glucose tolerance and impaired fasting glucose?
IGT and IFG show abnormalities of glucose regulation but no necessarily full blown diabetes. Both managed with lifestyle and annual review.
What is impaired fasting hyperglycaemia?
A person’s blood sugarlevels during fasting are consistently above the normal range, but below the diagnostic cut-off for a formal diagnosis of diabetes mellitus
6.1-6.9 mmol/L
