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5.3. DM 2 diagnosis
5.3.1. Diagnostic criteria
The diagnostic criteria endorsed by the American Diabetes Association (ADA) in
1997 (48) and by the World Health Organisation (WHO) in 1999 (6) try to avoid
the delay in the diagnosis in three possible ways; each one must be confirmed in
the days to follow, if there is no unequivocal hyperglycaemia (see table 1).
Table 1. DM 2 diagnostic criteria
1. Diabetes symptoms (polyuria, polydipsia and weight loss) and a casual plasma glucose (any time of
the day) >200 mg/dl.
2. Two determinations of fasting plasma glucose >126 mg/dl.. Lack of caloric intake in the previous eight
hours.
3. Two determinations of plasma glucose >200 mg/dl two fours after the oral glucose tolerance test with
75 g (OGTT).
It is important to highlight that the current diagnostic thresholds to define diabetes
are especially based on the increase of risk to suffer from microvascular complications
(mainly retinopathy) (48). Glycaemia thresholds to define an increase
in mortality and cardiovascular diseases are not established (49-51). Neither are
there sufficient data to define normal glycaemia levels.
Cohort
Studies
2+
5.3.2. Diagnostic methods
Fasting plasma glucose
This is the recommended method to diagnose diabetes and to perform population
studies. It is a detailed, low cost, reproducible and easy-to use test. Glucose measure
in plasma is approximately 11% higher than glucose measured in total blood
in a fasting or basal stage. In non-basal stages (postprandial), both determinations
are practically the same.
Oral Glucose Tolerance Test (OGTT)
This involves the determination of glycaemia in venous plasma two hours after a
75 g glucose intake in adults. Although it is a valid method to diagnose diabetes,
recommendations on its use differ.
CLINICAL PRACTICE GUIDELINE ON TYPE 2 DIABETES 41