Evidence-base - International Diabetes Federation

Global Guideline for Type 2 Diabetes
12
There are several options for strategies to screen for undiagnosed diabetes.
The ultimate choice is based on available resources and a trade-off between
sensitivity (the proportion of people with diabetes who test positive on the
screening test), specificity (the proportion of people who do not have diabetes
who test negative on the screening test), and the proportion of the population
with a positive screening test which needs to proceed to diagnostic testing.
Most screening strategies include risk assessment and measurement of
glycaemia, performed either sequentially or simultaneously. There are many
risk assessment methods and scores but applicability of many is limited
because they require tests not routinely available [10] . One commonly used risk
score is FINDRISK [11] . This diabetes risk score is a simple, fast, inexpensive,
noninvasive, and reliable tool to identify individuals at high risk for type 2
diabetes. It was developed from a large random population sample of individuals
with no antidiabetic medication at baseline and who were followed for 10
years. It requires age, body mass index (BMI), waist circumference, history of
antihypertensive drug treatment and high blood glucose, physical activity, and
daily consumption of fruits, berries, or vegetables to calculate risk.
Screening tests are followed by diagnostic tests in order to make the
diagnosis [1,12] . Combined screening strategies have a sensitivity and specificity
in the order of 75%, and 25% of the population require diagnostic testing. People
who screen negative should be re-tested after 3-5 years. These people should
also be offered lifestyle advice to minimise their risk of developing diabetes.
Although the usefulness of urine glucose as a screening test for undiagnosed
diabetes is limited because of low sensitivity (21-64%) [12] , specificity is high
(> 98%), so it may have a place in low-resource settings where other procedures
are not available.
Following a positive screening test, diagnostic testing is required. The WHO now
recommends three options for diagnosing diabetes [13,14] :
- FPG ≥ 7.0 mmol/l (≥ 126 mg/dl) or,
- 75 g OGTT with FPG ≥ 7.0 mmol/l (126 mg/dl) and / or 2 hour plasma glucose
≥ 11.1 mmol/l (200 mg/dl) or,
- HbA 1c ≥ 6.5% / 48 mmol/mol.
In asymptomatic individuals with a single abnormal test, the abnormal test
should be repeated to confirm the diagnosis unless the result is unequivocally
elevated.
In the presence of classical diabetes symptoms, diabetes can be diagnosed on
the basis of a random plasma glucose ≥ 11.1 mmol/l (200 mg/dl).
Consideration
The place of screening for undiagnosed diabetes as part of an overall
strategy to reduce the health burden of diabetes is not established. However,
many organisations recommend it. The choice of whether to screen or not,
and the screening strategy, must be made locally taking into account local
considerations.