Hyperglycaemia - initial assessment

Guidance for medical examiners when assessing a patient for either a general topic or condition – Hyperglycaemia - initial assessment.

Indication

• Test as per DAME Reference Chart
• Fasting glucose 5.5mmol/L or more
• See below for action on HbA1c 6.5% [48mmol/mol] or over

Procedural requirements

• 75g glucose tolerance test following overnight fast

Interpretation

• HbA1c 6.5% [48mmol/mol] or over: assess as Diabetic
• 2hr glucose >11mmol OR Two fasting glucose readings > 7mmol: assess as Diabetic
• 2hr glucose between 7.8 and 11: assess as Impaired Glucose Tolerance (IGT)
• 2hr glucose less than 7.8mmol and fasting glucose >6mmol: assess as Impaired Fasting Glucose (IFG) 
• ROLE of GTT and HbA1c: HbA1c levels have been validated in the diagnosis of diabetes. They have not been adequately validated in the estimation of cardiovascular disease risk, and cannot determine IFG and IGT, where elevated CVD risk also needs to be considered. For this reason, GTT remains the risk stratification tool where there is non-diabetic hyperglycaemia.

Further actions

• Diabetes require workup as per schedule:
  • Type 1 Diabetes - Insulin dependent - High risk of hypoglycaemia
  • Type 2 Diabetes - Insulin requiring - High risk of hypoglycaemia
  • Type 2 Diabetes - Non-insulin dependent - High risk of hypoglycaemia
  • Type 2 Diabetes - Non-insulin dependent - Low risk of hypoglycaemia
• Impaired Glucose Tolerance (IGT)
  • Cardiovascular Risk Assessment
  • GTT in 12 months
• Impaired Fasting Glucose (IFG)
  • Cardiovascular Risk Assessment
  • Fasting glucose in 12 months.

Pilot information

There is a strong link between abnormalities of glucose metabolism, heart disease and strokes. This includes both diabetes and 'pre-diabetes'.

The consequences of heart attacks and strokes are potentially serious.
In addition, abnormal glucose levels can affect many of the body systems such as eyes, kidneys and nerves.
There are well proven ways of managing these risks once they are identified, and so accurate diagnosis is important.  

References

• Diabetes Management in General Practice 2012/13
• Balkau B, Bertrais S, Ducimetiere P, Eschwege E. Is there a glycemic threshold for mortality risk? Dia Care. 1999 May 1;22(5):696-9.

Hyperglycaemia - initial assessment flowchart

A text version of the Hyperglycaemia - initial assessment flowchart is also available.

Hyperglycemia assessment flowchart

[1. d'Emden MC, Shaw JE, Colman PG, Colagiuri S, Twigg SM, Jones GR, et al. The role of HbA1c in the diagnosis of diabetes mellitus in Australia. Med J Aust 2012;197:220-1.]

ROLE of GTT and HbA1c

HbA1c levels have been validated in the diagnosis of diabetes. They have not been adequately validated in the estimation of cardiovascular disease risk, and cannot determine IFG and IGT, where elevated CVD risk also needs to be considered. For this reason, GTT remains the risk stratification tool where there is non-diabetic hyperglycaemia.

[Balkau B, Bertrais S, Ducimetiere P, Eschwege E. Is there a glycemic threshold for mortality risk? Dia Care. 1999 May 1;22(5):696-9.]