November 18, 2017
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Diabetes mellitus

WHO Diagnostic criteria 2011

HbA1c can be used as a diagnostic test for diabetes providing that stringent quality assurance tests are in place and assays are standardised to criteria aligned to the international reference values, and there are no conditions present which preclude its accurate measurement. This criterion was endorsed by the Department of health in England in 2011.

An HbA1c of 48 mmol/mol (6.5%) is recommended as the cut point for diagnosing diabetes. A value of less than 48 mmol/mol (6.5%) does not exclude diabetes diagnosed using glucose tests.

HbA1c ≥48 mmol/mol can be used to diagnose diabetes in most situations. In patients without diabetes symptoms repeat venous HbA1c in the same lab within 2 weeks. If the second sample is <48 mmol/mol (6.5%) treat as high risk of diabetes and repeat the test in 6 months or sooner if diabetes symptoms develop. In symptomatic adults with relatively slow onset of symptoms a single result ≥48 mmol/mol will suffice.

Situations where HbA1c must not be used as the sole test to diagnose diabetes

HbA1c reflects glycaemia over the preceding 2 – 3 months so may not be raised if blood glucose levels have risen rapidly. Examples:
  • ALL symptomatic children and young people Symptoms suggesting Type 1 diabetes (any age)
  • Short duration diabetes symptoms
  • Patients at high risk of diabetes who are acutely ill
  • Taking medication that may cause rapid glucose rise e.g. corticosteroids, antipsychotics
  • Acute pancreatic damage/pancreatic surgery

Situations where HbA1c should NOT be used
  • HbA1c may be falsely low in patients with haemoglobinopthies

  • HbA1c may give falsely high values in patients with iron deficiency anaemia

Recommended targets for metabolic control in diabetes

 

Good

Borderline

Poor

fasting plasma glucose (mmol/L)

4.4-6.1

6.2-7.8

> 7.8

post-prandial plasma glucose (mmol/L)

4.4-8.0

8.1-10.0

> 10.0

HbA1c (mmol/mol)

< 48

49-58

> 59

Urine glucose (%)

0

0-0.5

> 0.5

total cholesterol (mmol/L)

< 5.2

5.2-6.5

> 6.5

HDL cholesterol (mmol/L)

> 1.1

0.9-1.1

< 0.9

fasting triglyceride (mmol/L)

< 1.7

1.7-2.2

> 2.2

Body mass index (kg/m2) - Females

19-24

25-26

> 26

Body mass index (kg/m2) - Males

20-25

26-27

> 27

blood pressure (mm Hg)

< 140/90

140/90-160/90

> 160/90

Smoking

non-smoker

pipe

cigarette

References

JHB 9 June 2012

  

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