192 Diabetes Mellitus
diagnosed in childhood or adolescence, type 1 diabetes may
develop and be diagnosed at any age. Because markers of the
autoimmune destruction of the pancreatic beta cells are now
understood, major clinical trials are underway to intervene
with patients at risk for developing type 1 diabetes. A variety
of treatments are being used in an attempt to delay or prevent
the development of overt type 1 diabetes.
Type 2 diabetes is the most prevalent form of diabetes, en-
compassing approximately 90% of cases. Type 2 diabetes re-
sults from insulin resistance (i.e., low cellular sensitivity to
insulin) and/or a defect in insulin secretion that results in rel-
ative (as opposed to absolute) insulin de“ciency. Most, but
not all, patients with type 2 diabetes are obese, which tends
to increase insulin resistance. Because the level of hyper-
glycemia develops gradually and may be less severe, up to
50% of type 2 patients are undiagnosed (Expert Committee
on the Diagnosis and Classi“cation of Diabetes Mellitus,
2000). Thus, the hyperglycemia may be •silentlyŽ causing
end organ complications. Risk factors for type 2 diabetes
include older age, obesity, lack of physical activity, family
history of diabetes, prior history of gestational diabetes, im-
paired glucose tolerance, and race/ethnicity (CDC, 1998).
There is also a strong, but poorly understood, genetic compo-
nent to type 2 diabetes.
From a physiological perspective, the successful manage-
ment of diabetes is operationally de“ned as the patient•s level
of glycemic (i.e., blood glucose) control. This is most com-
monly measured using glycosylated hemoglobin (GHb)
assays (also referred to as glycohemoglobin, glycated hemo-
globin, HBA1c, or HbA 1 ). GHb levels yield an estimate of
average blood glucose (BG) levels over the previous two to
three months (ADA, 2000b). GHb assays are routinely
performed as part of standard diabetes care and are com-
monly used as outcome measures in research. In addition, the
data provided by patients• records of their self-monitored BG
levels are important indicators of daily BG levels and
variability.
The goal of treatment for all diabetes patients is to achieve
normal or as near normal as possible BG levels. The impor-
tance of this goal has been “rmly established for type 1 pa-
tients by the Diabetes Control and Complications Trial
Research Group (DCCT, 1993) and for type 2 patients by
the United Kingdom Prospective Diabetes Study Group
(UKPDS, 1998). Both of these randomized clinical trials de-
termined that patients on intensive treatment regimens were
able to achieve better glycemic control and signi“cantly re-
duce their risk for diabetes complications. For example, the
DCCT found a 50% to 75% risk reduction for the develop-
ment or progression of retinopathy, nephropathy, and neuro-
pathy in the intensive treatment group.
To achieve these important risk reductions in diabetes
complications, there has been renewed clinical effort to work
effectively with patients to achieve the tightest glycemic
control feasible for a given patient•s circumstances. For most
patients, these goals can be achieved only through an in-
tensive treatment regimen that places a strong emphasis on
self-management. As reviewed by the ADA (2000a), the
treatment components for type 1 and type 2 patients include
medical nutrition therapy; self-monitoring of BG (SMBG);
regular physical activity; physiologically based insulin
regimens when needed; oral glucose-lowering agents when
needed; and regular medical care to modify treatment, screen
for complications, and provide education and support. The
selection of regimen components and their intensity are
individualized for each patient•s particular needs, resulting in
great variability in treatment both between patients and
within a patient over time. For example, patients may be
either prescribed insulin or not, and those on insulin may per-
form between one and four injections per day or use a contin-
uous infusion insulin pump. The treatment of diabetes is not
static: The patient is required to balance these multiple treat-
ment components in everyday life, adjusting for a myriad of
factors that affect BG throughout the day. Thus, diabetes is
truly a chronic disease that can be effectively treated only
through a combination of skilled medical care and optimal
self-management.ADHERENCE IN DIABETESThe daily treatment regimen for diabetes is complex, de-
manding, and necessitates not only knowledge and technical
skills, but also the ability to modify the treatment compo-
nents as needed to achieve optimal glycemic control. Given
the complexity of this regimen and the fact that it is required
on a daily basis for the rest of the patient•s life, it is not sur-
prising that many type 1 and type 2 diabetes patients (40% to
90%) have dif“culty following treatment recommendations
(McNabb, 1997).
Adherence is commonly referred to as the extent to which
a person•s behavior (in terms of taking medications, follow-
ing diets, or executing lifestyle changes) coincides with med-
ical advice (Haynes, 1979). As McNabb (1997) pointed out,
the de“nition of adherence can be expanded to include
important patient-centered notions„the degree to which a
patient follows a predetermined set of behaviors or actions
(established cooperatively by the patient and provider) to
care for diabetes on a daily basis. It is in this spirit that the
termadherenceis used throughout the remainder of this
chapter.