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News & Information
CDC Statements on Diabetes Issues
Diagnosis and Classification of Diabetes Mellitus
- Who developed the new guidelines for the diagnosis and
classification of diabetes, and what was CDC's role?
- What are the major recommendations in the report for
the diagnosis and classification of diabetes?
- What is CDC's opinion on the recommendations made by
the Expert Committee on the Diagnosis and Classification of Diabetes
Mellitus?
- What scientific research supports these recommendations?
- What is the rationale for screening people aged 45 years
and over every 3 years?
- What are the public health implications and challenges?
- What are the economic implications?
- What impact will these recommendations have on CDC's
state diabetes control programs?
- What impact will these recommendations have on the National
Diabetes Education Program?
- What CDC activities will further understanding of the
committee's recommendations?
1. Who developed the new guidelines for the diagnosis and classification
of diabetes, and what was CDC's role?
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An international Expert Committee on the Diagnosis and Classification
of Diabetes Mellitus working under the sponsorship of the American Diabetes
Association (ADA) developed the new guidelines. The committee published
its report in Diabetes Care 1997; 20(7):1183-97, which was updated in
Diabetes Care
2004;27:S5-S10.*
The committee had 17 members including clinicians and researchers from
academia, the private sector, the National Institutes of Health (NIH),
and the ADA. Open collaboration in the World Health Organization (WHO)
occurred.
No Centers for Disease Control and Prevention (CDC) experts were on the
committee, but they were consulted during the process. They reviewed and
commented on preliminary drafts of the report, and provided some epidemiologic
data to the committee. Among other sources of information, CDC's data
were used to study the diagnostic criteria.
2. What are the major recommendations in the report for the diagnosis
and classification of diabetes?
The major recommendations in the report include the following:
For classification
- Eliminate using the confusing terms insulin-dependent diabetes mellitus
(IDDM) and non-insulin-dependent diabetes mellitus (NIDDM).
- Replace IDDM or juvenile-onset diabetes with "type 1 diabetes"
to describe diabetes characterized primarily by an absolute deficiency
of insulin.
- Replace NIDDM or adult-onset diabetes with "type 2 diabetes"
to describe diabetes characterized primarily by insulin resistance (that
is, insulin ineffective in target tissue) and inadequate compensatory
insulin secretory response.
- Use a category called "other specific types" in cases where
specific genetic defects, surgery, drugs, or other things, have caused
hyperglycemia.
- The committee retained the term gestational diabetes mellitus (GDM)
as a fourth category to describe diabetes that develops during pregnancy.
- Impaired glucose tolerance or IGT (2-hour post-meal glucose between
140 and 199 milligrams/deciliter or mg/dl) and impaired fasting glucose
(IFG) between 110 mg/dl and 125 mg/dl) are now risk categories for diabetes
mellitus.
For diagnosis
- Lower the current fasting diagnostic criteria from 140 mg/dl (7.7
millimole/liter or mmol/l) to 126 mg/dl (7.0 mmol/l). It is currently
recommended that subjects with single positive diagnostic tests should
have a repeat positive test before the diagnosis is made.
- Eliminate the routine clinical use of oral glucose tolerance tests
(OGTT), which use a 75-gram (g) glucose meal before measuring the plasma
glucose 2 hours after consumption. The OGTT is more difficult and more
expensive to perform than fasting glucose tests. Further, considerable
variation exists in the 2-hour post-meal glucose level.
- In general, these recommendations increase "sensitivity"
of fasting plasma glucose (FPG) and reduce "specificity" slightly.
The rationale for this direction is that studies indicate that glucose
control reduces microvascular complications, and that about one-fourth
of people with type 2 diabetes already have complications at the time
of diagnosis.
For testing
- Consider testing for diabetes for all people aged 45 years and older;
if normal, repeat testing every 3 years.
- Consider testing those below age 45, or test them more frequently,
if they are at high risk for diabetes including those who
- are obese
- have a family member with diabetes
- are members of high-risk ethnic groups such as African Americans,
Hispanics, or American Indians
- have delivered a baby weighing 9 pounds or were diagnosed with
GDM
- are hypertensive
- have a blood lipid abnormality.
- The committee recommended not screening women with a "low risk"
for GDM.
3. What is CDC's opinion on the recommendations made by the Expert Committee
on the Diagnosis and Classification of Diabetes Mellitus?
CDC strongly recommends that the new diagnostic and classification criteria
be adopted, promulgated, and implemented by all individuals and organizations
that identify and care for people with diabetes. The new diagnostic criteria
are based on sound scientific evidence. On balance, patients should benefit
by having a greater opportunity to be diagnosed and to receive treatment
before complications develop. Simultaneously, more data are necessary
to validate and support the committee's recommendation to test all people
45 years and older every 3 years.
The entire issue of GDM needs further investigation and discussion.
4. What scientific research supports these recommendations?
For classification
- In proposing the new classification system, the committee considered
the data and rationale for the current classification system that was
adopted in 1979, along with research findings of the last 18 years.
The present classification is based on etiologic pathophysiology, rather
than on treatments used.
For diagnosis
- Data from several population-based studies were used as the basis
of the recommendations for the new fasting diagnostic values; studies
included the U.S. National Health and Nutritional Examination Survey
III (NHANES III), the Pima Indians, and data from surveillance investigations
in Egypt.
For testing
- As mentioned previously, limited data support testing people aged
45 years and older every 3 years. However, the committee members concurred
that this approach was logical and reasonable on the basis of the Diabetes
Control and Complications Trial (DCCT), the pilot phase of the Veterans
Administration study on type 2 diabetes, the United Kingdom Prospective
Diabetes Study, and Wisconsin Epidemiologic Study of Diabetic Retinopathy
(WESDR) data.
5. What is the rationale for screening people aged 45 years and over every
3 years?
The committee cited the following reasons:
- the steep rise in the incidence of diabetes after age 45
- the negligible likelihood of developing significant and serious complications
from diabetes within 3 years of an initial negative test, for example,
if diabetes developed the "day after" the initial negative
tests, but before retesting in 3 years.
At present, CDC does not recommend broad-based, population screening
programs.
6. What are the public health implications and challenges?
Data from the NHANES III survey (a U.S. population-based survey) were
used to develop the new diagnostic criteria (that is, using the new fasting
measurement alone with no OGTT). These criteria lower the estimated total
(diagnosed and undiagnosed) diabetes prevalence in people 40 to 74 years
of age to 12.3%, compared with 14.3% found by applying the WHO's current
diagnostic criteria, which uses both a fasting value of 140 mg/dl and
the OGGT measurement. The impact of the new FPG criteria on total prevalence
will vary by clinic and state.
However, the new fasting diagnostic criteria will help find asymptomatic
people with undiagnosed diabetes because of the utility and ease of obtaining
fasting measurements compared with the difficulty of using OGTTs. The
number of people who shift from undiagnosed to diagnosed diabetes may
potentially increase the total by 2 million; that is, from 8 million to
10 million people diagnosed with diabetes. Thus, the new criteria should
begin to address the "missing 8 million."
Public health challenges include addressing issues for newly diagnosed
people, and issues for the health care system. Patient anxiety, personal
economic impact, insurability, and employability will need attention.
However, these concerns possibly will be overshadowed by the benefit to
the individual in terms of the potential of a healthier life and of living
fewer years with disabling diabetic complications.
Issues for the health care system include the following concerns:
- possible provider work overload with the number of newly identified
cases
- that this opportunity is used to make sure that newly diagnosed people
with diabetes get appropriate treatment to prevent microvascular and
macrovascular complications.
Ensuring that evidence-based, cost-effective interventions are used to
maximize the nation's investment value is critical.
7. What are the economic implications?
The use of the new fasting criteria will identify a higher proportion
of those with diabetes who are currently undiagnosed. As noted, about
2 million people with diabetes may be diagnosed. This may initially result
in an increase in diabetes expenditures. However, over a lifetime, the
cost may decrease to care for people with diabetes diagnosed using the
new criteria, because disease will be diagnosed at an earlier stage and
complications may be easier to prevent.
No scientific study, to date, has been carried out to support or refute
these conjectures. However, CDC is presently engaged in a cost-effectiveness
analysis of more active screening programs.
8. What impact will these recommendations have on CDC's state diabetes
control programs?
The new recommendations will probably result in people with early, undiagnosed
diabetes being found more frequently. Most of these new cases will have
few diabetic complications, if any. Identifying cases earlier provides
an opportunity and greater "potential" to prevent microvascular
and macrovascular complications. State diabetes control programs will
need to emphasize using the fasting criteria to diagnose cases to aggressively
prevent complications in newly diagnosed people, along with those with
diabetes of longer duration.
9. What impact will these recommendations have on the National Diabetes
Education Program?
These issues may require that National Diabetes Education Program representatives
develop initiatives that focus on adopting, communicating, and implementing
the new recommendations, which include the classification system, the
diagnostic criteria, and the testing algorithm. Emphasizing quality care
of patients with newly diagnosed diabetes and considering the role of
diet and physical activity as an aggressive initial treatment option will
also be important.
10. What CDC activities will further understanding of the committee's
recommendations?
Currently, most of CDC's focus is on important public health research
issues. Activities include the following:
- CDC's Division of Diabetes Translation (DDT) dedicated a Translation
Advisory Committee meeting to reviewing the public health issues related
to screening and early detection of diabetes. Participants explored
in detail public health screening issues related to research, programs,
and policies. This effort has been supportive of CDC's current research
agenda.
- CDC will perform an epidemiologic study to examine the effect that
screening and early detection have on development and progression of
diabetic complications. This critical question has not been studied
directly.
- CDC will conduct studies to characterize the performance of various
screening tests to detect undiagnosed diabetes. This information is
critical for cost-effectiveness studies.
- CDC will collaborate with state diabetes control programs to develop
and characterize the performance of various population-based diabetes
screening strategies.
- CDC will use statistical models to conduct cost-effectiveness studies
of screening for undiagnosed diabetes and the benefit it may have compared
to typical clinical diagnosis.
The findings of this research agenda should enhance CDC's ability to
support an effective, efficient, and appropriate public health response
to the impact of diabetes in the United States.
Return to CDC Statements on Diabetes Issues
Page last reviewed: August 31, 2007
Page last modified: December 20, 2005
Content Source: National Center for Chronic Disease Prevention and Health Promotion
Division of Diabetes Translation
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