[acb-diabetics] diagnosis and management of type 2 diabetes

[Patricia LaFrance-Wolf]

Diagnosis_and_Management_of_Type_2_DiabetesSteve V. Edelman, MD

Robert R. Henry, MD 

 

Certain key clinical and metabolic parameters should be monitored during
office visits:


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*	To assess glycemic control: 

*	A1C level 
*	Plasma glucose values 

*	To assess CV risk: 

*	Lipoprotein analysis 
*	Blood pressure 
*	Body weight 

*	To assess for evidence of diabetic complications: 

*	Kidney test 
*	Dilated eye examination 
*	Foot examination. 

The metabolic goals for these parameters are shown in Table 13.1.

Glycemic control is assessed during office visits with determinations of
plasma glucose levels and assays for glycated hemoglobin. Patients can
evaluate the effects of their treatment regimen on a day-to-day basis
between office visits by using SMBG at home. A combination of physician and
patient assessment methods are used to obtain the most accurate information
about the degree of metabolic control.

Measuring Plasma Glucose Concentrations

Day-to-day glycemic control is reflected in measurements of plasma glucose
concentrations. However, because this measurement is an isolated finding at
a single point in time, it may not represent a patient's usual metabolic
state. Some limitations of plasma glucose measurements include the
following:

*	It is difficult to know the meaning of a single random or fasting
plasma glucose determination. 


TABLE 13.1 - Metabolic Goals of Effective Management

. Glycosylated hemoglobin:

- Within 1% point above the upper range of normal (7%)

- Within 3 SD from the mean


. FPG level between 80 mg/dL and 120 mg/dL


. 2-hour postprandial plasma glucose level <160 mg/dL


. Systolic/diastolic blood pressure <130/85 mm Hg if no evidence of
proteinuria (<120/80 mm Hg with evidence of proteinuria)


. Approach or maintain ideal body weight


. Lipoprotein goals:

- Triglyceride level <150 mg/dL

- HDL cholesterol level >45 mg/dL (>55 in women)

- LDL cholesterol level <100 mg/dL

 

*	Random determinations may reflect peak, trough, or values in between
because of the wide daily variations in glucose levels. 
*	The stress of an office visit may result in higher than usual
glucose values. 
*	Some patients may become atypically adherent to their treatment
regimen or use extra insulin before an office visit, resulting in an
uncharacteristically low glucose level. 
*	The presence of an intercurrent illness at the time of an office
visit can alter blood glucose levels. 

Home glucose monitoring data are appropriate for assessing glycemic control
and making changes in the therapeutic regimen of patients being treated with
diet, oral agents, and insulin therapy. Inaccurate or suspicious results
would be revealed by a glycated hemoglobin assay, which reflects the level
of glucose control for the preceding 2 to 3 months. Because a single plasma
glucose measurement does not provide an adequate assessment of any type of
therapy, other corroborating data, such as symptoms of hypoglycemia or
uncontrolled diabetes, a glycated hemoglobin value, and repeated plasma
glucose measurements, are needed.

The timing of plasma glucose measurements has an impact on the significance
of the findings:

*	A postprandial sample obtained 1 to 2 hours after a patient has
eaten is the most sensitive measurement because glucose levels are the
highest during this time; total carbohydrate content of the meal will be
reflected in this glucose value. 
*	A preprandial or fasting plasma glucose level reflects how
efficiently carbohydrates from a meal have been cleared from the plasma. 

 

Measuring Glycated Hemoglobin 

Assays of HbA1, A1C, and glycated hemoglobin are used extensively to provide
an accurate time-integrated measure of average glycemic control over the
previous 2 to 3 months and to correlate plasma glucose measurements and
patients' SMBG results. Because these assays do not reflect the glucose
level at the time a blood sample is tested, measurements of glycated
hemoglobin are not useful for making day-to-day adjustments in the treatment
regimen. 

Glycation refers to a carbohydrate-protein linkage. This irreversible
process occurs as glucose in the plasma attaches itself to the hemoglobin
component of red blood cells. Because the life span of red blood cells is
120 days, glycated hemoglobin assays reflect average blood glucose
concentration over that time. 

The amount of circulating glucose concentration to which the red cell is
exposed influences the amount of glycated hemoglobin. Therefore, the
hyperglycemia of diabetes causes an increase in the percentage of glycated
hemoglobin in patients with diabetes; A1C shows the greatest change, whereas
the remaining glycated hemoglobin's are relatively stable. 

Levels of A1C and HbA1 correlate best with the degree of diabetic control
obtained several months earlier. Regardless of which assay is used, however,
certain conditions can interfere with obtaining accurate results: 

*	False low concentrations are likely in the presence of conditions
that decrease the life of the red blood cell, such as: 

*	Hemolytic anemia 
*	Bleeding 
*	Sickle cell trait 

*	False high concentrations are likely in the presence of conditions
that increase the life span of the red blood cell, e.g., patients without a
spleen. Other conditions that produce falsely elevated glycated hemoglobin's
include: 

*	Uremia 
*	High concentrations of fetal hemoglobin 
*	High aspirin doses (>10 g/day) 
*	High concentrations of ethanol. 

Regular monitoring of glycated hemoglobin (e.g., every 3 to 6 months) is
essential for all patients with diabetes, regardless of their type of
therapy. On a daily basis, patients typically measure capillary blood
glucose levels before meals, postprandially, and at bedtime, particularly
with intensive insulin regimens in which near-normal glycemia is being
actively pursued. Even when preprandial levels seem satisfactory, patients'
glycated hemoglobin results often are higher than expected. This finding
would not have been evident through glucose measurements alone, and the need
for further efforts to control blood glucose would not have been apparent
without obtaining a glycated hemoglobin measurement. Home A1C testing is now
available (Becton, Dickinson). The patient applies a drop of blood to a
reagent card, which is mailed to a central laboratory. The results are then
mailed back to the patient.

A disposable test kit for glycosylated A1C is now available for home testing
by patients with diabetes ( <http://www.a1ctest.com/> Click here for
A1cTest.com.) 

Next Week, Measuring Other Glycated Proteins and Self-Monitoring of Blood
Glucose

You can purchase this textalt at Amazon.com, just click on this link:
Diagnosis and Management of Type 2 Diabetes 10E
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SUGGESTED READING

American Diabetes Association. Standards of medical care in diabetes --
2010. Diabetes Care. 2010;33(suppl 1):S11-S61. 

 

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