ADA
Standards Miss-Diagnosed 69% of Those with Diabetes and 89% of IGT
Patients
American
Diabetes Association (ADA) criteria for diagnosing diabetes in obese
patients underestimate the prevalence of the disease, according to a
comparison by researchers in France.
The
World Health Organization (WHO) and ADA provide diagnostic guidelines
for diabetes and pre-diabetes conditions. The two organizations differ
significantly in their reliance on the oral glucose tolerance test (OGTT)
as a diagnostic tool. ADA recommends that fasting plasma glucose
values are sufficient for diagnosis and discourages OGTT. WHO, on the
other hand, argues strongly to retain routine OGTT in diagnostic
situations unless circumstances prevent its use. J. L. Richard and
colleagues working the Center for Medicine in Roi, France, compared
the accuracy of ADA guidelines for the diagnosis of diabetes and
intermediate glucose abnormalities to those of WHO.
A
total of 1167 subjects, 286 men and 881 women, participated in the
study. They ranged from 18 to 84 years old and had a body mass index
(BMI) of at least 30 kg/m & & 2 & & (a level
considered obese).
Researchers
administered an OGTT to each subject. Then, based on test results,
subjects were placed into one of three categories - normal glucose
tolerance (NGT), impaired glucose tolerance (IGT), or diabetes
mellitus (DM) - according to both WHO and ADA guidelines.
Significant
disagreement between the ADA and WHO guidelines occurred in each
category. Using the ADA criteria, the prevalence of (CD) was
3.7% compared with 10.6% under the WHO value, and rate of intermediate
glucose abnormalities was 6.0% under ADA criteria and 22.4% under WHO
(Diagnosis of diabetes mellitus and intermediate glucose abnormalities
in obese patients based on ADA (1997) and WHO (1985) criteria,
Diabetic Medicine, 2002;19(4):292-299).
"Moreover,
many patients defined as glucose-intolerant by the WHO 1985 criteria
were shifted to a more favorable metabolic status by ADA
criteria," Richard and coauthors pointed out.
Investigators
found that health care providers using ADA standards would have missed
diagnosing 69% of the patients considered diabetic under WHO criteria
and 89% of the patients considered IGT by WHO standards.
Fasting
blood glucose tests proved insensitive compared to the OGTT.
This
is a concern because research has suggested that microvascular and
macrovascular complications begin occurring at lower glucose levels
than previously thought.
"Since
it appears impossible to determine a reliable cut-off value for
fasting blood glucose to identify diabetic obese subjects with
sufficient sensitivity, our results justify the retention of the OGTT
in clinical practice or for epidemiological studies," Richard and
coauthors asserted.
The
corresponding author for this study is J.L. Richard, Department for
Nutritional Diseases and Diabetology, Center of Medicine, F-30240 Le
Grau Du Roi, France.
Key
points reported in this study include:
*Use
of the American Diabetic Association (ADA) diagnostic criteria
underestimated the extent of the disease in an obese population when
compared to diagnoses made under the World Health Organization (WHO)
standards
*Implementation
of the ADA criteria resulted in fewer diagnoses of diabetes and of
impaired glucose intolerance in obese people
*The
oral glucose tolerance test (OGTT) is a more accurate method than a
fasting plasma glucose test for identifying people with impaired
glycemic control
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