|
Upon
successful completion of this course, you will be able to:
- List
and discuss the current Standards of Medical Care in Diabetes
- Explain
the existing systems for the Classification and Diagnosis
of diabetes
- Discuss
the processes of DETECTION AND DIAGNOSIS OF GDM
- Explain
the differences of DIABETES CARE IN SPECIFIC POPULATIONS
- Identify
and discuss the systems for Diagnosis and Classification
of Diabetes Mellitus
- Explain
the Diabetes Care in the School and Day Care Setting
The
American Diabetes Association (ADA) has been actively involved
in the development and dissemination of diabetes care standards,
guidelines, and related documents for many years. These statements
are published in one or more of the Associations professional
journals. This supplement contains ADAs "Standards
of Medical Care in Diabetes," our major position statement,
which contains all or key recommendations. In addition, contained
herein are selected position statements on certain topics
not adequately covered in the "Standards." We hope
that this is a convenient and important resource for all health
care professionals who care for people with diabetes.
ADA
Clinical Practice Recommendations consist of position statements
that represent official ADA opinion as denoted by formal review
and approval by the Professional Practice Committee and the
Executive Committee of the Board of Directors. ADA Statements,
consensus statements, and technical reviews are not official
ADA recommendations; however, they are produced under the
auspices of the Association by invited experts. These publications
are reviewed by the Professional Practice Committee for general
content and used as source documents for the updating of the
"Standards."
ADA
has adopted the following definitions for its clinically related
reports.
An
official point of view or belief of the ADA: Position statements
are issued on scientific or medical issues related to diabetes.
They are published in ADA journals and other scientific/medical
publications as appropriate. Position statements must be reviewed
and approved by the Professional Practice Committee and, subsequently,
by the Executive Committee of the Board of Directors. ADA
position statements are typically based on a technical review
or other published review and are peer reviewed on an annual
basis.
ADA
Statement
A
focused review on a clinical topic with recommendations. It
is authored, and the recommendations are those of the authors
based on the evidence presented. ADA Statements are reviewed
externally and also by the Professional Practice Committee
for overall content. As noted above, the recommendations made
are considered by the Professional Practice Committee as part
of the review and updating of the "Standards of Medical
Care in Diabetes."
Technical
Review
A
balanced review and analysis of the literature on a scientific
or medical topic related to diabetes. The technical review
provides a scientific rationale for a position statement and
undergoes peer review before submission to the Professional
Practice Committee for approval. In some cases, in place of
a technical review, original research publications, conference
proceedings, or other comprehensive review articles are used
as a basis for a position statement.
Consensus
Statement
A
comprehensive examination by a panel of experts (i.e., consensus
panel) of a scientific or medical issue related to diabetes.
A consensus statement is developed immediately following a
consensus conference at which presentations are made on the
issue under review. The statement represents the panels
collective analysis, evaluation, and opinion based in part
on the conference proceedings. The need for a consensus conference
arises when clinicians or scientists desire guidance on a
subject for which there is a relative deficiency of "evidence"
that might otherwise allow a more definite statement to be
made. Once written by the panel, a consensus statement is
not subject to subsequent review or approval and does not
represent official Association opinion.
The
Associations Professional Practice Committee is responsible
for reviewing official position statements. Appointment to
the Professional Practice Committee is based on excellence
in clinical practice and research. The committee comprises
physicians, diabetes educators, and registered dietitians
who have expertise in a range of areas, including adult and
pediatric endocrinology, epidemiology and public health, lipid
research, hypertension, and preconception and pregnancy care.
The committee regularly reviews each previously approved statement
and makes necessary revisions. Both new and revised position
statements are also reviewed by outside experts, after which
they are approved by the Executive Committee.
Grading
of Scientific Evidence
Since the ADA first began publishing practice guidelines,
considerable evolution has occurred in the evaluation of scientific
evidence and in the development of evidence-based guidelines.
Accordingly, we have developed a classification system to
grade the quality of scientific evidence supporting ADA recommendations.
The system outlined in Table 1 will be used for all new and
revised ADA position statements.
Recommendations have been assigned ratings of A, B, or C,
depending on the quality of evidence (Table
1). Expert opinion (E) is a separate category for recommendations
in which there is as yet no evidence from clinical trials,
in which clinical trials may be impractical, or in which there
is conflicting evidence. Recommendations with an "A"
rating are based on large well-designed clinical trials or
well-done meta-analyses. Generally, these recommendations
have the best chance of improving outcomes when applied to
the population to which they are appropriate. Recommendations
with lower levels of evidence may be equally important but
are not as well supported. This supplement contains seven
statements that have used this system. The level of evidence
supporting a given recommendation is noted either as a heading
for a group of recommendations or after a given recommendation
in parentheses.
Table
1 ADA evidence grading system for clinical practice
recommendations
|
Level
of evidence
|
Description |
|
A
|
Clear
evidence from well-conducted, generalizable, randomized
controlled trials that are adequately powered, including:
Evidence from a well-conducted multicenter trial
Evidence
from a meta-analysis that incorporated quality ratings
in the analysis
Compelling nonexperimental evidence, i.e., "all
or none" rule developed by the Center for Evidence
Based Medicine at Oxford*Supportive
evidence from well-conducted randomized controlled trials
that are adequately powered, including:
Evidence from a well-conducted trial at one or more
institutions
Evidence from a meta-analysis that incorporated
quality ratings in the analysis
|
|
B
|
Supportive
evidence from well-conducted cohort studies, including:
Evidence from a well-conducted prospective cohort study
or registry
Evidence from a well-conducted meta-analysis
of cohort studiesSupportive
evidence from a well-conducted case-control study
|
|
C
|
Supportive
evidence from poorly controlled or uncontrolled studies,
including:
Evidence from randomized clinical trials with one
or more major or three or more minor methodological flaws
that could invalidate the results
Evidence from observational studies with high potential
for bias (such as case series with comparison with historical
controls)
Evidence from case series or case reports
Conflicting evidence with the weight of evidence supporting
the recommendation |
|
E
|
Expert
consensus or clinical experience |
*
Either all patients died before therapy and at least some
survived with therapy or some patients died without therapy
and none died with therapy. Example: use of insulin in the
treatment of diabetic ketoacidosis.
Of course, evidence is only one component of clinical decision-making.
Clinicians care for patients, not populations; guidelines
must always be interpreted with the needs of the individual
patient in mind. Individual circumstances, such as comorbid
and coexisting diseases, age, education, disability, and,
above all, patients values and preferences, must also
be considered and may lead to different treatment targets
and strategies. Also, conventional evidence hierarchies, such
as the one adapted by the ADA, may miss some nuances that
are important in diabetes care. For example, while there is
excellent evidence from clinical trials supporting the importance
of achieving glycemic control, the optimal way to achieve
this result is less clear. It is difficult to assess each
component of such a complex intervention.
The
ADA will continue to improve and update the Clinical Practice
Recommendations to ensure that clinicians, health plans, and
policy makers can continue to rely on them as the most authoritative
and current guidelines for diabetes care.
|
Standards
of Medical Care in Diabetes2006
|
American
Diabetes Association
Abbreviations:
ABI, ankle-brachial index AMI, acute myocatdial infarction
ARB, angiotensin receptor blocker CAD, coronary
artery disease CBG, capillary blood glucose
CHD, coronary heart disease CHF, congestive heart failure
CKD, chronic kidney disease CVD, cardiovascular
disease DCCB, dihydropyridine calcium channel blocker
DCCT, Diabetes Control and Complications Trial
DKA, diabetic ketoacidosis DMMP, diabetes medical management
plan DPN, distal symmetric polyneuropathy DPP,
Diabetes Prevention Program DRI, dietary reference
intake DRS, Diabetic Retinopathy Study DSME,
diabetes self-management education DSMT, diabetes self-management
training ECG, electrocardiogram ESRD, end-stage
renal disease ETDRS, Early Treatment Diabetic Retinopathy
Study FDA, Food and Drug Administration FPG,
fasting plasma glucose GDM, gestational diabetes mellitus
GFR, glomerular filtration rate HRC, high-risk
characteristic ICU, intensive care unit IFG,
impaired fasting glucose IGT, impaired glucose tolerance
MNT, medical nutrition therapy NPDR, nonproliferative
diabetic retinopathy OGTT, oral glucose tolerance test
PAD, peripheral arterial disease PDR, proliferative
diabetic retinopathy PPG, postprandial plasma glucose
RDA, recommended dietary allowance SMBG, self-monitoring
of blood glucose TZD, thiazolidinedione
Diabetes
is a chronic illness that requires continuing medical care
and patient self-management education to prevent acute complications
and to reduce the risk of long-term complications. Diabetes
care is complex and requires that many issues, beyond glycemic
control, be addressed. A large body of evidence exists that
supports a range of interventions to improve diabetes outcomes.
These
standards of care are intended to provide clinicians, patients,
researchers, payors, and other interested individuals with
the components of diabetes care, treatment goals, and tools
to evaluate the quality of care. While individual preferences,
comorbidities, and other patient factors may require modification
of goals, targets that are desirable for most patients with
diabetes are provided. These standards are not intended to
preclude more extensive evaluation and management of the patient
by other specialists as needed.
The
recommendations included are diagnostic and therapeutic actions
that are known or believed to favorably affect health outcomes
of patients with diabetes. A grading system (Table
1), developed by the American Diabetes Association (ADA)
and modeled after existing methods, was utilized to clarify
and codify the evidence that forms the basis for the recommendations.
The level of evidence that supports each recommendation is
listed after each recommendation using the letters A, B, C,
or E.
|
I.
Classification and Diagnosis
|
A.
Classification
In
1997, the ADA issued new diagnostic and classification criteria;
in 2003, modifications were made regarding the diagnosis of
impaired fasting glucose (IFG). The classification of diabetes
includes four clinical classes:
- Type
1 diabetes (results from ß-cell destruction, usually
leading to absolute insulin deficiency).
- Type
2 diabetes (results from a progressive insulin secretory
defect on the background of insulin resistance).
- Other
specific types of diabetes due to other causes, e.g., genetic
defects in ß-cell function, genetic defects in insulin
action, diseases of the exocrine pancreas (such as cystic
fibrosis), and drug or chemical induced (such as in the
treatment of AIDS or after organ transplantation).
- Gestational
diabetes mellitus (GDM) (diagnosed during pregnancy).
B. Diagnosis
Recommendations
- The
FPG is the preferred test to diagnose diabetes in children
and nonpregnant adults. (E)
- The
use of the A1C for the diagnosis of diabetes is not recommended
at this time. (E)
Criteria
for the diagnosis of diabetes in nonpregnant adults are shown
in Table 2. Three ways to diagnose diabetes are available,
and each must be confirmed on a subsequent day unless unequivocal
symptoms of hyperglycemia are present. Although the 75-g oral
glucose tolerance test (OGTT) is more sensitive and modestly
more specific than fasting plasma glucose (FPG) to diagnose
diabetes, it is poorly reproducible and rarely performed in
practice. Because of ease of use, acceptability to patients,
and lower cost, the FPG is the preferred diagnostic test.
It should be noted that the vast majority of people who meet
diagnostic criteria for diabetes by OGTT, but not by FPG,
will have an A1C value <7.0%. The use of the A1C for the
diagnosis of diabetes is not recommended at this time.
Table
2 Criteria for the diagnosis of diabetes
|
1.
|
Symptoms
of diabetes and a casual plasma glucose 200 mg/dl (11.1
mmol/l). Casual is defined as any time of day without
regard to time since last meal. The classic symptoms
of diabetes include polyuria, polydipsia, and unexplained
weight loss. OR
|
|
2.
|
FPG
126 mg/dl (7.0 mmol/l). Fasting is defined as no caloric
intake for at least 8 h. OR
|
|
3.
|
2-h
plasma glucose 200 mg/dl (11.1 mmol/l) during an OGTT.
The test should be performed as described by the World
Health Organization, using a glucose load containing the
equivalent of 75-g anhydrous glucose dissolved in water. |
Hyperglycemia
not sufficient to meet the diagnostic criteria for diabetes
is categorized as either IFG or impaired glucose tolerance
(IGT), depending on whether it is identified through a FPG
or an OGTT:
- IFG
= FPG 100 mg/dl (5.6 mmol/l) to 125 mg/dl (6.9 mmol/l)
- IGT
= 2-h plasma glucose 140 mg/dl (7.8 mmol/l) to 199 mg/dl
(11.0 mmol/l)
Recently,
IFG and IGT have been officially termed "pre-diabetes."
Both categories, IFG and IGT, are risk factors for future
diabetes and cardiovascular disease (CVD).
In
the absence of unequivocal hyperglycemia, these criteria should
be confirmed by repeat testing on a different day. The OGTT
is not recommended for routine clinical use but may be required
in the evaluation of patients with IFG (see text) or when
diabetes is still suspected despite a normal FPG, as with
the postpartum evaluation of women with GDM.
|
II.
Screening for Diabetes
|
Recommendations
- Screening
to detect pre-diabetes (IFG or IGT) and diabetes should
be considered in individuals 45 years of age, particularly
in those with a BMI 25 kg/m2. Screening should also be considered
for people who are <45 years of age and are overweight
if they have another risk factor for diabetes (Table
3). Repeat testing should be carried out at 3-year intervals.
(E)
- Screen
for pre-diabetes and diabetes in high-risk, asymptomatic,
undiagnosed adults and children within the health care setting.
(E)
- To
screen for diabetes/pre-diabetes, either an FPG test or
2-h OGTT (75-g glucose load) or both are appropriate. (B)
- An
OGTT may be considered in patients with IFG to better define
the risk of diabetes. (E)
Table
3 Criteria for testing for diabetes in asymptomatic
adult individuals
|
1.
|
Testing
for diabetes should be considered in all individuals
at age 45 years and above, particularly in those with
a BMI 25 kg/m2*, and, if normal, should be repeated
at 3-year intervals. |
|
2.
|
Testing
should be considered at a younger age or be carried
out more frequently in individuals who are overweight
(BMI 25 kg/m2*) and have additional risk factors:
are habitually physically inactive
have a first-degree relative with diabetes
are members of a high-risk ethnic population
(e.g., African American, Latino, Native American, Asian
American, Pacific Islander)
have delivered a baby weighing >9 lb or have
been diagnosed with GDM
are hypertensive ( 140/90 mmHg)
have an HDL cholesterol level <35 mg/dl (0.90
mmol/l) and/or a triglyceride level >250 mg/dl (2.82
mmol/l)
have PCOS
on previous testing, had IGT or IFG
have other clinical conditions associated with
insulin resistance (e.g. PCOS or acanthosis nigricans)
have a history of vascular disease |
*
May not be correct for all ethnic groups. PCOS, polycystic
ovary syndrome.
There is a major distinction between diagnostic testing and
screening. Both utilize the same clinical tests, which should
be done within the context of the health care setting. When
an individual exhibits symptoms or signs of the disease, diagnostic
tests are performed, and such tests do not represent screening.
The purpose of screening is to identify asymptomatic individuals
who are likely to have diabetes or pre-diabetes. Separate
diagnostic tests using standard criteria are required after
positive screening tests to establish a definitive diagnosis
as described above.
Type
1 diabetes
Generally,
people with type 1 diabetes present with acute symptoms of
diabetes and markedly elevated blood glucose levels. Because
of the acute onset of symptoms, most cases of type 1 diabetes
are detected soon after symptoms develop. Widespread clinical
testing of asymptomatic individuals for the presence of autoantibodies
related to type 1 diabetes cannot be recommended at this time
as a means to identify individuals at risk. Reasons for this
include the following:
- cutoff
values for some of the immune marker assays have not been
completely established in clinical settings;
- there
is no consensus as to what action should be taken when a
positive autoantibody test result is obtained; and
- because
the incidence of type 1 diabetes is low, testing of healthy
children will identify only a very small number (<0.5%)
who at that moment may be "pre-diabetic." Clinical
studies are being conducted to test various methods of preventing
type 1 diabetes in high-risk individuals (e.g., siblings
of type 1 diabetic patients). These studies may uncover
an effective means of preventing type 1 diabetes, in which
case targeted screening may be appropriate in the future.
Type
2 diabetes
Type
2 diabetes is frequently not diagnosed until complications
appear, and approximately one-third of all people with diabetes
may be undiagnosed. Individuals at high risk should be screened
for diabetes and pre-diabetes. Criteria for testing for diabetes
in asymptomatic, undiagnosed adults are listed in Table
3. The effectiveness of early diagnosis through screening
of asymptomatic individuals has not been determined.
Screening
should be carried out within the health care setting. Either
an FPG test or 2-h OGTT (75-g glucose load) is appropriate.
The 2-h OGTT identifies people with IGT, and thus, more people
who are at increased risk for the development of diabetes
and CVD. It should be noted that the two tests do not necessarily
detect the same individuals. It is important to recognize
that although the efficacy of interventions for primary prevention
of type 2 diabetes have been demonstrated among individuals
with IGT, such data among individuals with IFG (who do not
also have IGT) are not available. The FPG test is more convenient
to patients, more reproducible, less costly, and easier to
administer than the 2-h OGTT. Therefore, the recommended initial
screening test for nonpregnant adults is the FPG. An OGTT
may be considered in patients with IFG to better define the
risk of diabetes. The incidence of type 2 diabetes in children
and adolescents has increased dramatically in the last decade.
Consistent with screening recommendations for adults, only
children and youth at increased risk for the presence or the
development of type 2 diabetes should be tested (Table
4).
Table
4 Testing for type 2 diabetes in children
Criteria:
- Overweight
(BMI >85th percentile for age and sex, weight for height
>85th percentile, or weight >120% of ideal for height)
Plus
any two of the following risk factors:
- Family
history of type 2 diabetes in first- or second-degree relative
- Race/ethnicity
(Native American, African American, Latino, Asian American,
Pacific Islander)
- Signs
of insulin resistance or conditions associated with insulin
resistance (acanthosis nigricans, hypertension, dyslipidemia,
or PCOS)
- Maternal
history of diabetes or GDM
Age
of initiation: age 10 years or at onset of puberty, if puberty
occurs at a younger age
Frequency: every 2 years
Test: FPG preferred
Clinical
judgment should be used to test for diabetes in high-risk
patients who do not meet these criteria. PCOS, polycystic
ovary syndrome.
The
effectiveness of screening may also depend on the setting
in which it is performed. In general, community screening
outside a health care setting may be less effective because
of the failure of people with a positive screening test to
seek and obtain appropriate follow-up testing and care or,
conversely, to ensure appropriate repeat testing for individuals
who screen negative. That is, screening outside of clinical
settings may yield abnormal tests that are never discussed
with a primary care provider, low compliance with treatment
recommendations, and a very uncertain impact on long-term
health. Community screening may also be poorly targeted, i.e.,
it may fail to reach the groups most at risk and inappropriately
test those at low risk (the worried well) or even those already
diagnosed.
On
the basis of expert opinion, screening should be considered
by health care providers at 3-year intervals beginning at
age 45, particularly in those with BMI 25 kg/m2. The rationale
for this interval is that false negatives will be repeated
before substantial time elapses, and there is little likelihood
of an individual developing any of the complications of diabetes
to a significant degree within 3 years of a negative screening
test result. Testing should be considered at a younger age
or be carried out more frequently in individuals who are overweight
and have one or more of the other risk factors for type 2
diabetes.
|
III.
DETECTION AND DIAGNOSIS OF GDM
|
Recommendations
- Screen
for diabetes in pregnancy using risk factor analysis and,
if appropriate, use of an OGTT. (C)
- Women
with GDM should be screened for diabetes 612 weeks
postpartum and should be followed up with subsequent screening
for the development of diabetes or pre-diabetes. (E)
Risk
assessment for GDM should be undertaken at the first prenatal
visit. Women with clinical characteristics consistent with
a high risk for GDM (those with marked obesity, personal history
of GDM, glycosuria, or a strong family history of diabetes)
should undergo glucose testing as soon as possible. An FPG
126 mg/dl or a casual plasma glucose 200 mg/dl meets the threshold
for the diagnosis of diabetes and needs to be confirmed on
a subsequent day unless unequivocal symptoms of hyperglycemia
are present. High-risk women not found to have GDM at the
initial screening and average-risk women should be tested
between 24 and 28 weeks of gestation. Testing should follow
one of two approaches:
- One-step
approach: perform a diagnostic 100-g OGTT
- Two-step
approach: perform an initial screening by measuring the
plasma or serum glucose concentration 1 h after a 50-g oral
glucose load (glucose challenge test) and perform a diagnostic
100-g OGTT on that subset of women exceeding the glucose
threshold value on the glucose challenge test. When the
two-step approach is used, a glucose threshold value 140
mg/dl identifies 80% of women with GDM, and the yield is
further increased to 90% by using a cutoff of 130 mg/dl.
Diagnostic
criteria for the 100-g OGTT are as follows: 95 mg/dl fasting,
180 mg/dl at 1 h, 155 mg/dl at 2 h, and 140 mg/dl at 3 h.
Two or more of the plasma glucose values must be met or exceeded
for a positive diagnosis. The test should be done in the morning
after an overnight fast of 814 h. The diagnosis can
be made using a 75-g glucose load, but that test is not as
well validated for detection of at-risk infants or mothers
as the 100-g OGTT.
Low-risk
status requires no glucose testing, but this category is limited
to those women meeting all of the following characteristics:
- Age
<25 years.
- Weight
normal before pregnancy.
- Member
of an ethnic group with a low prevalence of GDM.
- No
known diabetes in first-degree relatives.
- No
history of abnormal glucose tolerance.
- No
history of poor obstetric outcome.
|
IV.
PREVENTION/DELAY OF TYPE 2 DIABETES
|
Recommendations
- 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)
- Patients
with IGT should be given counseling on weight loss as well
as instruction for increasing physical activity. (A)
- Patients
with IFG should be given counseling on weight loss as well
as instruction for increasing physical activity. (E)
- Follow-up
counseling appears important for success. (B)
- Monitoring
for the development of diabetes in those with pre-diabetes
should be performed every 12 years. (E)
- 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)
Studies
have been initiated in the last decade to determine the feasibility
and benefit of various strategies to prevent or delay the
onset of type 2 diabetes. Five well-designed randomized controlled
trials have been reported. The strategies shown to be effective
in preventing diabetes relied on lifestyle modification or
glucose-lowering drugs that have been approved for treating
diabetes.
In
the Finnish study, middle-aged obese subjects with IGT were
randomized to receive either brief diet and exercise counseling
(control group) or intensive individualized instruction on
weight reduction, food intake, and guidance on increasing
physical activity (intervention group). After an average follow-up
of 3.2 years, there was a 58% relative reduction in the incidence
of diabetes in the intervention group compared with the control
subjects.
In
the Diabetes Prevention Program (DPP), enrolled subjects were
slightly younger and more obese but had nearly identical glucose
intolerance compared with subjects in the Finnish study. About
45% of the participants were from minority groups (e.g., African
American, Hispanic), and 20% were 60 years of age. Subjects
were randomized to one of three intervention groups, which
included the intensive nutrition and exercise counseling ("lifestyle")
group or either of two masked medication treatment groups:
the biguanide metformin group or the placebo group. The latter
interventions were combined with standard diet and exercise
recommendations. After an average follow-up of 2.8 years,
a 58% relative reduction in the progression to diabetes was
observed in the lifestyle group and a 31% relative reduction
in the progression of diabetes was observed in the metformin
group compared with control subjects. On average, 50% of the
lifestyle group achieved the goal of 7% weight reduction and
74% maintained at least 150 min/week of moderately intense
activity. In the troglitazone arm of the DPP (discontinued
after a mean of 0.9 years when the drug was withdrawn from
the market), troglitazone markedly reduced the incidence of
diabetes during the period the drug was given.
In
the Da Qing Study, men and women from health care clinics
in the city of Da Qing, China, were screened with OGTT, and
those with IGT were randomized by clinic to a control group
or to one of three active treatment groups: diet only, exercise
only, or diet plus exercise. Subjects were reexamined biannually,
and after an average of 6 years follow-up, the diet,
exercise, and diet plus exercise interventions were associated
with 31, 46, and 42% reductions in risk of developing type
2 diabetes, respectively.
Three
other studies, each using a different class of glucose-lowering
agent, have shown a reduction in progression to diabetes with
pharmacological intervention. In the Troglitazone in Prevention
of Diabetes (TRIPOD) study, Hispanic women with previous GDM
were randomized to receive either placebo or troglitazone
(a drug now withdrawn from commercial sale in the U.S. but
belonging to the thiazolidinedione [TZD] class). After a median
follow-up of 30 months, troglitazone treatment was associated
with a 56% relative reduction in progression to diabetes.
In the STOP-IDDM trial, participants with IGT were randomized
in a double-blind fashion to receive either the -glucosidase
inhibitor acarbose or a placebo. After a mean follow-up of
3.3 years, a 25% relative risk reduction in progression to
diabetes, based on one OGTT, was observed in the acarbose-treated
group compared with the placebo group. If this diagnosis was
confirmed by a second OGTT, a 36% relative risk reduction
was observed in the acarbose group compared with the placebo
group.
Finally,
in the XENical in the prevention of Diabetes in Obese Subjects
(XENDOS) study, orlistat was examined for its ability to delay
type 2 diabetes when added to lifestyle change in a group
with BMI 30 kg/m2 with or without IGT. After 4 years of treatment,
the effect of orlistat addition corresponded to a 45% risk
reduction in the IGT group, with no effect observed in those
without IGT.
Our
knowledge of the early stages of hyperglycemia that portend
the diagnosis of diabetes, and the recent success of major
intervention trials, clearly show that individuals at high
risk can be identified and diabetes delayed, if not prevented.
The cost-effectiveness of intervention strategies is unclear,
but the huge burden resulting from the complications of diabetes
and the potential ancillary benefits of some of the interventions
suggest that an effort to prevent diabetes is worthwhile.
Lifestyle
modification
In
well-controlled studies that included a lifestyle intervention
arm, substantial efforts were necessary to achieve only modest
changes in weight and exercise, but those changes were sufficient
to achieve an important reduction in the incidence of diabetes.
In the Finnish Diabetes Prevention Study, weight loss averaged
9.2 lb at 1 year, 7.7 lb after 2 years, and 4.6 lb after 5
years; "moderate exercise," such as brisk walking,
for 30 min/day was suggested. In the Finnish study, there
was a direct relationship between adherence with the lifestyle
intervention and the reduced incidence of diabetes.
In
the DPP, the lifestyle group lost 12 lb at 2 years and 9 lb
at 3 years (mean weight loss for the study duration was 12
lb or 6% of initial body weight). In both of these studies,
most of the participants were obese (BMI >30 kg/m2).
A
low-fat (<25% fat) intake was recommended; if reducing
fat did not produce weight loss to goal, calorie restriction
was also recommended. Participants weighing 120174 lb
(5478 kg) at baseline were instructed to follow a 1,200-kcal/day
diet (33 g fat), those 175219 lb (7999 kg) were
instructed to follow a 1,500-kcal/day diet (42 g fat), those
220249 lb (100113 kg) were instructed to follow
an 1,800-kcal/day diet (50 g fat), and those >250 lb (114
kg) were instructed to follow a 2,000-kcal/day diet (55 g
fat).
Pharmacological
interventions
Three
diabetes prevention trials used pharmacological therapy, and
all have reported a significant lowering of the incidence
of diabetes. The biguanide metformin reduced the risk of diabetes
by 31% in the DPP, the -glucosidase inhibitor acarbose reduced
the risk by 32% in the STOP-IDDM trial, and the TZD troglitazone
reduced the risk by 56% in the TRIPOD study.
In
the DPP, metformin was about half as effective as diet and
exercise in delaying the onset of diabetes overall, but it
was nearly ineffective in older individuals ( 60 years of
age) or in those who were less overweight (BMI <30 kg/m2).
Conversely, metformin was as effective as lifestyle modification
in individuals aged 2444 years or in those with a BMI
35 kg/m2. Thus, the population of people in whom treatment
with metformin has equal benefit to that of a lifestyle intervention
is only a small subset of those who are likely to have pre-diabetes
(IFG or IGT).
There
are also data to suggest that blockade of the renin-angiotensin
system may lower the risk of developing diabetes, but more
studies are necessary before these drugs can be recommended
for preventing diabetes.
Lifestyle
or medication?
The
DPP is the only study in which a comparison of the two was
made, and lifestyle modification was nearly twice as effective
in preventing diabetes (58 vs. 31% relative reductions, respectively).
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 (510%
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.
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. Public health messages, health care professionals,
and health care systems should all encourage behavior changes
to achieve a healthy lifestyle. Further research is necessary
to understand better how to facilitate effective and efficient
programs for the primary prevention of type 2 diabetes.
A.
Initial evaluation
A
complete medical evaluation should be performed to classify
the patient, detect the presence or absence of diabetes complications,
assist in formulating a management plan, and provide a basis
for continuing care. If the diagnosis of diabetes has already
been made, the evaluation should review the previous treatment
and the past and present degrees of glycemic control. Laboratory
tests appropriate to the evaluation of each patients
general medical condition should be performed. A focus on
the components of comprehensive care (Table 5) will assist
the health care team to ensure optimal management of the patient
with diabetes.
Table
5 Components of the comprehensive diabetes evaluation
Medical
history
- Symptoms,
results of laboratory tests, and special examination results
related to the diagnosis of diabetes
- Prior
A1C records
- Eating
patterns, nutritional status, and weight history; growth
and development in children and adolescents
- Details
of previous treatment programs, including nutrition and
diabetes self-management education, attitudes, and health
beliefs
- Current
treatment of diabetes, including medications, meal plan,
and results of glucose monitoring and patients use
of data
- Exercise
history
- Frequency,
severity, and cause of acute complications such as ketoacidosis
and hypoglycemia
- Prior
or current infections, particularly skin, foot, dental,
and genitourinary infections
- Symptoms
and treatment of chronic eye; kidney; nerve; genitourinary
(including sexual), bladder, and gastrointestinal function
(including symptoms of celiac disease in type 1 diabetic
patients); heart; peripheral vascular; foot; and cerebrovascular
complications associated with diabetes
- Other
medications that may affect blood glucose levels
- Risk
factors for atherosclerosis: smoking, hypertension, obesity,
dyslipidemia, and family history
- History
and treatment of other conditions, including endocrine and
eating disorders
- Assessment
for mood disorder
- Family
history of diabetes and other endocrine disorders
- Lifestyle,
cultural, psychosocial, educational, and economic factors
that might influence the management of diabetes
- Tobacco,
alcohol, and/or controlled substance use
- Contraception
and reproductive and sexual history
Physical
examination
- Height
and weight measurement (and comparison to norms in children
and adolescents)
- Sexual
maturation staging (during pubertal period)
- Blood
pressure determination, including orthostatic measurements
when indicated, and comparison to age-related norms
- Fundoscopic
examination
- Oral
examination
- Thyroid
palpation
- Cardiac
examination
- Abdominal
examination (e.g., for hepatomegaly)
- Evaluation
of pulses by palpation and with auscultation
- Hand/finger
examination
- Foot
examination
- Skin
examination (for acanthosis nigricans and insulin-injection
sites)
- Neurological
examination
- Signs
of diseases that can cause secondary diabetes (e.g., hemochromatosis,
pancreatic disease)
Laboratory
evaluation
- A1C
- Fasting
lipid profile, including total cholesterol, HDL cholesterol,
triglycerides, and LDL cholesterol, liver function tests
with further evaluation for fatty liver or hepatitis if
abnormal
- Test
for microalbuminuria in type 1 diabetic patients who have
had diabetes for at least 5 years and in all patients with
type 2 diabetes; some advocate beginning screening of pubertal
children before 5 years of diabetes
- Serum
creatinine and calculated GFR in adults (check creatinine
in children if proteinuria is present)
- Thyroid-stimulating
hormone (TSH) in all type 1 diabetic patients; in type 2
if clinically indicated
- Electrocardiogram
in adults, if clinically indicated
- Urinalysis
for ketones, protein, sediment
Referrals
- Eye
exam, if indicated
- Family
planning for women of reproductive age
- MNT,
as indicated
- Diabetes
educator, if not provided by physician or practice staff
- Behavioral
specialist, as indicated
- Foot
specialist, as indicated
- Other
specialties and services as appropriate
B.
Management
People
with diabetes should receive medical care from a physician-coordinated
team. Such teams may include, but are not limited to, physicians,
nurse practitioners, physicians assistants, nurses,
dietitians, pharmacists, and mental health professionals with
expertise and a special interest in diabetes. It is essential
in this collaborative and integrated team approach that individuals
with diabetes assume an active role in their care.
The
management plan should be formulated as an individualized
therapeutic alliance among the patient and family, the physician,
and other members of the health care team. Any plan should
recognize diabetes self-management education (DSME) as an
integral component of care. In developing the plan, consideration
should be given to the patients age, school or work
schedule and conditions, physical activity, eating patterns,
social situation and personality, cultural factors, and presence
of complications of diabetes or other medical conditions.
A variety of strategies and techniques should be used to provide
adequate education and development of problem-solving skills
in the various aspects of diabetes management. Implementation
of the management plan requires that each aspect is understood
and agreed on by the patient and the care providers and that
the goals and treatment plan are reasonable.
C.
Glycemic control
1.
Assessment of glycemic control
Techniques
are available for health providers and patients to assess
the effectiveness of the management plan on glycemic control.
a.
Self-monitoring of blood glucose
Recommendations
- Clinical
trials using insulin that have demonstrated the value of
tight glycemic control have used self-monitoring of blood
glucose (SMBG) as an integral part of the management strategy.
(A)
- SMBG
should be carried out three or more times daily for patients
using multiple insulin injections. (A)
- For
patients using less frequent insulin injections or oral
agents or medical nutrition therapy (MNT) alone, SMBG is
useful in achieving glycemic goals. (E)
- To
achieve postprandial glucose targets, postprandial SMBG
may be appropriate. (E)
- Instruct
the patient in SMBG and routinely evaluate the patients
technique and ability to use data to adjust therapy. (E)
The
ADAs consensus statements on SMBG provide a comprehensive
review of the subject. Major clinical trials assessing the
impact of glycemic control on diabetes complications have
included SMBG as part of multifactorial interventions, suggesting
that SMBG is a component of effective therapy. SMBG allows
patients to evaluate their individual response to therapy
and assess whether glycemic targets are being achieved. Results
of SMBG can be useful in preventing hypoglycemia and adjusting
medications, MNT, and physical activity.
The
frequency and timing of SMBG should be dictated by the particular
needs and goals of the patients. Daily SMBG is especially
important for patients treated with insulin to monitor for
and prevent asymptomatic hypoglycemia and hyperglycemia. For
most patients with type 1 diabetes and pregnant women taking
insulin, SMBG is recommended three or more times daily. The
optimal frequency and timing of SMBG for patients with type
2 diabetes on oral agent therapy is not known but should be
sufficient to facilitate reaching glucose goals. Patients
with type 2 diabetes on insulin typically need to perform
SMBG more frequently than those not using insulin. When adding
to or modifying therapy, type 1 and type 2 diabetic patients
should test more often than usual. The role of SMBG in stable
diet-treated patients with type 2 diabetes is not known.
Because
the accuracy of SMBG is instrument and user dependent, it
is important for health care providers to evaluate each patients
monitoring technique, both initially and at regular intervals
thereafter. In addition, optimal use of SMBG requires proper
interpretation of the data. Patients should be taught how
to use the data to adjust food intake, exercise, or pharmacological
therapy to achieve specific glycemic goals. Health professionals
should evaluate at regular intervals the patients ability
to use SMBG data to guide treatment.
b.
A1C
Recommendations
- Perform
the A1C test at least two times a year in patients who are
meeting treatment goals (and who have stable glycemic control).
(E)
- Perform
the A1C test quarterly in patients whose therapy has changed
or who are not meeting glycemic goals. (E)
- Use
of point-of-care testing for A1C allows for timely decisions
on therapy changes, when needed. (E)
By
performing an A1C test, health providers can measure a patients
average glycemia over the preceding 23 months and, thus,
assess treatment efficacy. A1C testing should be performed
routinely in all patients with diabetes, first to document
the degree of glycemic control at initial assessment and then
as part of continuing care. Since the A1C test reflects mean
glycemia over the preceding 23 months, measurement approximately
every 3 months is required to determine whether a patients
metabolic control has been reached and maintained within the
target range. Thus, regular performance of the A1C test permits
detection of departures from the target (Table
6) in a timely fashion. For any individual patient, the
frequency of A1C testing should be dependent on the clinical
situation, the treatment regimen used, and the judgment of
the clinician.
Table
6 Summary of recommendations for adults with diabetes
| Glycemic
control |
|
| |
A1C |
<7.0%* |
| |
Preprandial
capillary plasma glucose |
90130
mg/dl (5.07.2 mmol/l) |
| |
Peak
postprandial capillary plasma glucose |
<180
mg/dl (<10.0 mmol/l) |
| |
Blood
pressure |
<130/80
mmHg |
| Lipids
|
|
| |
LDL |
<100 mg/dl (<2.6 mmol/l) |
| |
Triglycerides
|
<150
mg/dl (<1.7 mmol/l) |
| |
HDL
|
>40
mg/dl (>1.1 mmol/l) |
Key
concepts in setting glycemic goals:
- A1C
is the primary target for glycemic control
- Goals
should be individualized
- Certain
populations (children, pregnant women, and elderly) require
special considerations
-
More stringent glycemic goals (i.e., a normal A1C, <6%)
may further reduce complications at the cost of increased
risk of hypoglycemia
- Less
intensive glycemic goals may be indicated in patients with
severe or frequent hypoglycemia
- Postprandial
glucose may be targeted if A1C goals are not met despite
reaching preprandial glucose goals
*
Referenced to a nondiabetic range of 4.06.0% using a
DCCT-based assay.
**
Postprandial glucose measurements should be made 12
h after the beginning of the meal, generally peak levels in
patients with diabetes.
^
Current NCEP/ATP III guidelines suggest that in patients with
triglycerides 200 mg/dl, the "non-HDL cholesterol"
(total cholesterol minus HDL) be utilized. The goal is 130
mg/dl (34).
$
For women, it has been suggested that the HDL goal be increased
by 10 mg/dl.
The
A1C test is subject to certain limitations. Conditions that
affect erythrocyte turnover (hemolysis, blood loss) and hemoglobin
variants must be considered, particularly when the A1C result
does not correlate with the patients clinical situation.
The availability of the A1C result at the time that the patient
is seen (point of care testing) has been reported to result
in the frequency of intensification of therapy and improvement
in glycemic control.
Glycemic
control is best judged by the combination of the results of
the patients SMBG testing (as performed) and the current
A1C result. The A1C should be used not only to assess the
patients control over the preceding 23 months
but also as a check on the accuracy of the meter (or the patients
self-reported results) and the adequacy of the SMBG testing
schedule. |