Investigations

Question 1

How would you investigate someone with suspected diabetes mellitus?

Answer 1

• 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

Question 2

If testing random glucose, what is diagnostic of diabetes?

Answer 2

Value of >/= 11.1 mmol/L on 2 seperate occasions, or on one occasion with symptoms

Question 3

If testing fasting glucose, what is diagnostic of diabetes?

Answer 3

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

Question 4

If testing glucose tolerance, what is diagnostic of diabetes?

Answer 4

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

Question 5

If testing HbA1c, what is diagnostic of diabetes?

Answer 5

Value >/= 48 mmol/L

Question 6

What is HbA1c?

Answer 6

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.

Question 7

When would you not use HbA1c for diagnosis of diabetes?

Answer 7

• Pregnancy
• Children
• Type I diabetes
• Haemoglobinopathies
• Renal Failure
• HIV infection
• Corticosteroid use

Question 8

In an adult, what would you challaenge them with as part of the glucose tolerance test?

Answer 8

75g glucose in 300 ml water

Question 9

For a glucose tolerance test, when are measurements taken?

Answer 9

Fasting and 120 minute sample

Question 10

What is classed as impaired glucose tolerance?

Answer 10

• <7.0 mmol/L fasting
• 7.8-11.0 post challenge

Question 11

What is classed as impaired fasting glucose?

Answer 11

Fasting plasma glucose between 6.1 and 6.9 mmol/L

Question 12

Besides glucose testing, what other tests might you do in someone with suspected diabetes?

Answer 12

Look for complications

• Fundoscopy
• U+E’s and Dipstick
• Neurovascular examination

Question 13

What is impaired fasting hyperglycaemia?

Answer 13

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