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The Importance of Testing for Pre-diabetes—Using the Right Tool
For practical reasons, FPG alone is often used for diabetes screening. saw a similar reduction in pre-diabetes progression (32%).
13
The third
This method is relatively convenient and less expensive than OGTT.
4
For study used troglitazone and saw the most dramatic risk reduction
an FPG test, a venous blood sample is drawn in the physician’s office (56%).
14
Data from this trial suggest true prevention, rather than simply
following a 12-hour overnight fast. This specimen is analyzed in a core a delay of progression.
14
Of note, the use of metformin was most
laboratory. According to the 2003 ADA consensus guidelines, an FPG successful in a small subset of patients with pre-diabetes, namely those
level between 100mg/dl (5.5mmol/l) and 125mg/dl (6.9mmol/l)is defined who were younger (24–44 years of age) and more overweight (body
as IFG, or pre-diabetes. For an OGTT, a venous blood sample is also mass index [BMI] ≥35kg/m
2
).
12
drawn in the physician’s office after a 12-hour overnight fast. The patient
is administered a 75g oral dose of glucose. The patient must remain in While lifestyle modification is relatively free of side effects,
the physician’s office until a second venous blood sample is collected pharmacological intervention is not. Even though medications such as
two hours after the glucose dose. Both fasting and two-hour samples acarbose, metformin, or troglitazone may have benefits, the benefits
are analyzed in a core laboratory. If the first result falls in the impaired should outweigh the risks for any individual patient. Drug therapy of any
fasting glucose range, or the two-hour post-dose result lies between kind is generally associated with side effects, some of which may
140mg/dl (7.8mmol/l) and 199mg/dl (11.1mmol/l), these results are be severe; for this reason, pharmacological intervention should be
indicative of IGT, or pre-diabetes. As mentioned, FPG alone is commonly considered a second choice after lifestyle changes.
12
used to screen for diabetes, but an OGTT more reliably detects diabetes.
The same can be said for the detection of pre-diabetes. Studies have Laboratory Testing
demonstrated that FPG alone detects only 30–65% of patients with To date, the measurement of fasting plasma glucose levels on venous
diabetes, while OGTT detects around 90%.
3,5
For this reason, OGTT is still blood samples has been the standard means of diagnosing diabetes. An
considered a standard method for diagnosis of diabetes. abnormal fasting plasma glucose test that is followed by an OGTT aids
in the discrimination of IFG, IGT, or overt diabetes. In recent years, great
Pre-diabetes and the Benefits of Intervention advances have been made in the field of point-of-care testing (POCT).
The importance of identifying diabetes and pre-diabetes is related to the The ability to perform tests and obtain results faster at the point of care
risk of developing complications from elevated blood glucose levels.
2
(POC) has been especially significant in the monitoring and
Studies
6–11
have shown that early signs of diabetic complications such management of diabetes. Patients and practitioners are able to check a
as retinopathy and cardiovascular disease were found relatively early patient’s blood glucose rapidly at the bedside, at home, or in the
in the diagnosis of diabetes, suggesting that these disease states doctor’s office. However, POC blood glucose monitoring is especially
were already present or developing well before an official diagnosis susceptible to errors due to pre-analytical, analytical, and post-
of diabetes was made.
2
Since patients can develop complications of analytical effects,
15
given that a range of clinical staff and patients
diabetes before diagnosis, early detection and intervention can be without laboratory experience are performing the test. It is this rise in
of great benefit. The risk of progression from pre-diabetes to type 2 the use of POCT that has led to the question of whether POCT can be
diabetes is quite high, especially if left untreated. When detected early, used in the diagnosis of diabetes. Before POC glucose meters can
the patient may not only delay but even prevent progression to be used in the diagnosis of diabetes, the device results should match
diabetes. Disease prevention is significantly less expensive than the the technical performance of any currently accepted diagnostic tool.
treatment of frank hyperglycemia and diabetic complications. One of the most important technical criteria is the accuracy or
agreement between glucose meter results and the laboratory glucose
The primary intervention for pre-diabetes, as with type 2 diabetes, is levels analyzed in a centralized laboratory. The ADA recommends that
lifestyle modification. Weight loss, reduced fat intake, increased fiber glucose meter results agree with a central laboratory within ±5%, 100%
intake, and increased physical activity
2
have consistently demonstrated of the time. This goal has been difficult to achieve because of the many
benefits in preventing or delaying the progression from pre-diabetes to factors that influence POCT.
15
diabetes.
2
The difficulty of maintaining even modest lifestyle changes
makes compliance with this treatment option challenging and Operator effects are the most important influences on glucose meter
maintenance of new habits difficult.
12
A considerable amount of effort results and include level of training, motivation, device portability, and
and motivation from fitness trainers and nutritionists is needed to ease of use. Clinical staff such as nurses do not have the level of
implement and foster these lifestyle modifications.
12
However, even laboratory experience or training compared with medical technologists
modest changes in weight or exercise can lead to a reduction in the and are generally motivated more by patient care than by laboratory
incidence of diabetes.
12
While lifestyle modifications provide improved concerns.
15
Device maintenance can become a secondary issue despite
outcomes, better strategies are still needed to aid patients in its importance in the accuracy of test results. Precision, which is
compliance. Currently, there are no provisions in the US healthcare the measure of reproducibility of results, can also be affected. As the
system to aid or reimburse patients for periodic lifestyle counseling.
12
number of operators with varying degrees of motivation and experience
Other treatment options for pre-diabetes are pharmacological. Three perform the same test, result variability can increase. Patients, in turn,
diabetes prevention trials have tested the use of different medications may neglect device maintenance, most likely due to a lack of
to delay progression of pre-diabetes. The Diabetes Prevention Program understanding of the importance of device calibration and quality
(DPP) administered metformin and saw a 31% risk reduction for control. Glucose meter performance and subsequent results greatly
diabetes.
9–11
The use of acarbose, an α-glucosidase inhibitor, in the Study depend on technique. This includes device ease of use, simplicity of strip
to Prevent Non-Insulin-Dependent Diabetes Mellitus (STOP-NIDDM) trial insertion, and blood application.
15
US ENDOCRINOLOGY 23
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