IDF - working for people with diabetes around the world© IDF (Europe) 1999

A Desktop Guide to
Type 2 Diabetes

Section 1: Diagnosis of hyperglycaemic states


TYPE 2 DIABETES - 1 - DIAGNOSTIC CLASSIFICATION
( Top of page ) (Guidelines contents list ) ( Guidelines index )

1 DIAGNOSIS OF HYPERGLYCAEMIC STATES


Diagnostic background

The purpose of diagnosis is to identify those at risk of developing the complications of diabetes,
both arterial ( macrovascular ) and microvascular, as well as to deal with any symptoms

The levels of blood glucose vary for these different risks, and determine management


1.1 Management classification - hyperglycaemic states

1. Symptomatic ( biochemically confirmed ) = "Diabetes"
2. At risk of arterial and microvascular damage = "Diabetes"
3. At risk of arterial damage from hyperglycaemia = "Impaired Glucose Tolerance ( IGT )"
and of progression to diabetes or "Impaired Fasting Glycaemia ( IFG )"

1.2 Diagnostic algorithm

1. Symptomatic or glycosuria or incidental hyperglycaemia
Check random venous plasma glucose ( see below for capillary / venous equivalents )
If >11.0 mmol/l ( >=200 mg/dl ) = "Diabetes"
If >5.5 mmol/l ( >=100 mg/dl ) then proceed to next step (2.)
( and review cause of symptoms )
2. Random or fasting screening glucose >5.5 mmol/l ( >=100 mg/dl )
Check fasting venous plasma glucose
If >=7.0 mmol/l ( >125 mg/dl ), repeat and if confirmed = "Diabetes"
If >6.0 mmol/l ( >=110 mg/dl ) do oral glucose tolerance test ( OGTT )
If >5.0 mmol/l ( >90 mg/dl ), consider yearly reassessment of arterial risk factors,
including plasma glucose
OGTT ( venous plasma glucose ) :
If 2-h >11.0 mmol/l ( >=200 mg/dl ) = "Diabetes"
If 2-h <=11.0 mmol/l ( <200 mg/dl ) and >=7.8 mmol/l ( >=140 mg/dl ) = "IGT"
If fasting >6.0 mmol/l ( >=110 mg/dl ) and 2-h <7.8 mmol/l ( <140 mg/dl ) = "IFG"
See cautions below

1.3 Laboratory diagnostic equivalents for plasma and blood

Plasma glucose* Whole blood glucose
Venous* Capillary Venous Capillary
mmol/l mg/dl mmol/l mg/dl mmol/l mg/dl mmol/l mg/dl
Fasting
"Diabetes" >=7.0 >125 >=7.0 >125 >6.0 >=110 >6.0 >=110
"IFG" >6.0 >=110 >6.0 >=110 >5.5 >=100 >5.5 >=100
OGTT 2-h
"Diabetes" >11.0 >=200 >=12.2 >=220 >=10.0 >=180 >11.0 >=200
"IGT" >=7.8 >=140 >=8.9 >=160 >=6.7 >=120 >=7.8 >=140

* preferred measure
OGTT: 75 g glucose in 300 ml water over 3-5 min

( Top of 'Diagnostic classification' )

1.4 Diagnostic aids and cautions

1. Fasting glucose estimations require a certainty of no previous calorie intake

    • be suspicious if HbA1c not consistently elevated
    • if suspicious repeat after 2-h supervision, or consider OGTT
    • diagnosis cannot be based on a single abnormal glucose estimation in the absence of symptoms

2. Venous plasma glucose estimation is preferred

3. HbA1c ( glycated haemoglobin ) can be useful in clinical diagnosis

4. Diagnostic procedures should not be performed :

5. Diagnostic tests should be interpreted with reservation :

6. If suspicion or high risk of diabetes, but fasting glucose normal, do OGTT, particularly in the elderly

7. The above procedures are not applicable to people with hepatic cirrhosis or other extreme forms of peripheral insulin resistance

( Top of 'Diagnostic classification' )
TYPE 2 DIABETES - 1 - DIAGNOSTIC CLASSIFICATION

( Top of page ) (Guidelines contents list ) ( Guidelines index )