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U N I T 9
Endocrine System
releasing adequate insulin to facilitate storage, their
blood glucose levels rise above those observed in normal
people and remain elevated for longer periods.
Capillary Blood Glucose Monitoring.
Technological
advances have provided the means for monitoring
blood glucose levels by using a drop of capillary blood.
This procedure has provided health professionals with
a rapid and economical means for monitoring blood
glucose and has given people with diabetes a way of
maintaining near-normal blood glucose levels through
self-monitoring of blood glucose. These methods use a
drop of capillary blood obtained by pricking the finger
or forearm with a special needle or small lancet. Small
trigger devices make use of the lancet virtually painless.
The drop of capillary blood is placed on or absorbed by
a reagent strip, and glucose levels are determined elec-
tronically using a glucose meter.
Laboratory tests that use plasma for measurement of
blood glucose give results that are 10% to 15% higher
than the finger-stick method, which uses whole blood.
28
Many blood glucose monitors approved for home use
and some test strips now calibrate blood glucose read-
ings to plasma values. It is important that people with
diabetes know whether their monitors or glucose strips
provide whole-blood or plasma test results.
Continuous glucose monitoring (CGM) systems are
becoming available to fine-tune glucose management.
The various systems have small catheters implanted in
the subcutaneous tissue to provide frequent samples.
The variety and accuracy of these systems are continu-
ally improving. Finger-stick glucose monitoring remains
the standard of care, but does not provide as much
information regarding the glycemic profile as CGM
(especially during the overnight period).
Glycosylated Hemoglobin.
Glycosylated hemoglobin,
hemoglobin A
1C
(HbA
1C
), and A1C are terms used to
describe hemoglobin into which glucose has been incor-
porated. Hemoglobin normally does not contain glu-
cose when it is released from the bone marrow. During
its 120-day life span in the red blood cell, hemoglobin
becomes glycosylated to form HbA1. The major form
of HbA1 is HbA
1C
, which makes up 2% to 6% of total
hemoglobin.
3
Because glucose entry into red blood
cells is not insulin dependent, the rate at which glucose
becomes attached to the hemoglobin molecule depends
on blood glucose levels. Glycosylation is essentially irre-
versible, and the level of A1C present in the blood pro-
vides an index of blood glucose levels over the previous
6 to 12 weeks. In uncontrolled diabetes or diabetes with
hyperglycemia, there is an increase in the level of A1C.
The American Diabetes Association (ADA) recommends
initiating corrective measures for A1C levels greater
than an individualized goal. For example, the presence
of several factors including advanced age, history of
severe hypoglycemic episodes, and presence of cardio-
vascular disease might suggest a glycemic goal of 7.5%
to 8%, whereas the absence of these and other worrying
factors may mean that a target goal of 6.5% or less is
warranted as long as this can be achieved safely.
11
The A1C may overestimate glycemic burden in cer-
tain individuals and ethnic groups (such as African
Americans).
11
In addition, A1C can be misleading in
persons with certain forms of anemia and hemoglobin
disorders, and in pregnant women. For these popula-
tions, the diagnosis of diabetes must use glucose crite-
ria exclusively. Also, the A1C may not be significantly
elevated in rapidly evolving diabetes, such as the devel-
opment of type 1 diabetes in children.
UrineTests
The ease, accuracy, and convenience of self-adminis-
tered blood glucose monitoring techniques have made
urine testing for glucose obsolete for most people with
diabetes. These tests only reflect urine glucose levels and
are influenced by such factors as the renal threshold for
glucose, fluid intake and urine concentration, urine test-
ing methodologies, and some drugs. It is recommended
that all people with diabetes self-monitor their blood
glucose. Urine ketone determinations remain an impor-
tant part of monitoring diabetic control, particularly in
people with type 1 diabetes who are at risk for develop-
ment of ketoacidosis, and in pregnant diabetic women to
check the adequacy of nutrition and glycemic control.
28
Diabetes Management
The desired outcome of glycemic control in both type 1
and type 2 diabetes is normalization of blood glucose as a
means of preventing short- and long-term complications.
Treatment plans involve dietary management (medical
nutrition therapy), exercise, and antidiabetic agents.
People with type 1 diabetes require insulin therapy from
the time of diagnosis. Weight loss and dietary manage-
ment may be sufficient to control blood glucose levels
in people with type 2 diabetes. However, they require
follow-up care because insulin secretion from the beta
cells may decrease or insulin resistance may persist or
worsen, in which case non-insulin agents are prescribed.
Among the methods used to achieve these treatment
goals are education in self-management and problem
solving. Individual treatment goals should take into
account the person’s age and other disease conditions,
the person’s capacity to understand and carry out the
treatment regimen, and socioeconomic factors that
might influence compliance with the treatment plan.
Optimal control of both type 1 and type 2 diabetes is
associated with prevention or delay of chronic diabetes
complications.
Dietary Management
Dietary management usually is individualized to meet
the specific needs of each person with diabetes.
11,29
Therapy goals include maintenance of near-normal
blood glucose levels, achievement of optimal lipid levels,
adequate calories to attain and maintain a reasonable
weight, prevention and treatment of chronic diabe-
tes complications, and improvement of overall health
through optimal nutrition.
