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Identifying Appropriate Strategies for Diabetes Prevention
Abbreviations: CVD > cardiovascular disease DPP > Diabetes Prevention
Program FPG > fasting plasma glucose IFG > impaired fasting glucose IGT >
impaired glucose tolerance NNT > number needed to treat OGTT > oral glucose
tolerance test TRIPOD > Troglitazone in Prevention of Diabetes
Recent Clinical Practice Recommendations 2003 by American Diabetes Association
have indicated that there are now interventions capable of delaying the onset of
diabetes. Most of the diabetes prevention trials required that subjects have IGT
(defined as an FPG level <140 mg/dl and a 2-h OGTT value between 140 and 199
mg/dl) as the main enrollment criterion.
The strategies effective in preventing diabetes should rely on :
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Lifestyle modification or
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Glucose-lowering drugs that have been approved for treating
diabetes.
The greater benefit of weight loss and physical activity strongly suggests
that lifestyle modification
 should
be the first choice to prevent or delay diabetes. Modest weight loss (5–10%
of body weight) and modest physical activity (30 min daily) are the
recommended goals. Because this intervention not only has been shown to prevent
or delay diabetes, but also has a variety of other benefits, health care
providers should urge all overweight or sedentary individuals to adopt these
changes, and such recommendations should be made at every opportunity.
Drug therapy to prevent or delay diabetes appears to be much less beneficial for
a variety of reasons. First, when compared directly with lifestyle modification,
at least metformin was considerably less efficacious overall, and the advantage
of lifestyle modification was even greater in older or less overweight patients
. The relative risk reduction using acarbose appears similar to that of
metformin, although the study participants were very different. Second, all
glucose-lowering drugs require monitoring, have been associated with significant
adverse side effects, and are contraindicated in some individuals. Third, none
of the glucose-lowering agents tested or commercially available have been
studied with regard to protection against CVD or have any other clinical benefit
to non-diabetic individuals. Even in people with diabetes, there is only one
glucose-lowering agent (metformin) for which there is any outcome data to
suggest possible effectiveness in reducing the incidence of macrovascular
disease . Finally, prescribing a medication to delay the onset of diabetes,
which is also used to treat diabetes, will increase a patient’s total years of
drug exposure and may increase the likelihood of untoward drug effects.
Recommendations to prevent or delay diabetes
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Individuals at high risk for developing diabetes need to become aware of
the benefits of modest weight loss and participating in regular physical
activity. (A)
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Screening: based on current screening guidelines for diabetes (49), men
and women 45 years of age, particularly those with a BMI 25 kg/m2*, are
candidates for screening to detect pre-diabetes (IFG or IGT). Screening
should be considered in younger individuals with a BMI 25 kg/m2* who have
additional risk factors (Table 3). (B)
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In individuals with normoglycemia, rescreening at 3-year intervals is
reasonable. (C)
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How to screen: screening should be carried out only as part of a health
care office visit. Either an FPG test or 2-h OGTT (75-g glucose load) is
appropriate, and positive test results should be confirmed on another day.
(B)
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Intervention strategy: patients with pre-diabetes (IFG or IGT) should be
given counseling on weight loss as well as instruction for increasing
physical activity. (A)
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Follow-up counseling appears important for success. (B)
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Monitoring for the development of diabetes should be performed every 1–2
years. (E)
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Close attention should be given to, and appropriate treatment given for,
other CVD risk factors (e.g., tobacco use, hypertension, dyslipidemia). (A)
-
Drug therapy should not be routinely used to prevent diabetes until more
information is known about its cost-effectiveness. (E)
* May not be correct for all ethnic groups.
Therefore, when all factors are considered, there is insufficient evidence
to support the use of drug therapy as a substitute for, or routinely used in
addition to, lifestyle modification to prevent diabetes. Until there are studies
showing that drugs will delay or prevent the complications of diabetes, or until
the cost-effectiveness of using pharmacological agents has been established, ADA
does not recommend the routine use of these agents to prevent diabetes. For now
it seems that, lifestyle intervention to prevent diabetes appears to be very
safe, and, therefore, regular monitoring for untoward effects is unnecessary.
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