macrovascular complications result from changes in the medium to large blood
vessels. Blood vessel walls thicken, scle-rose, and become occluded by plaque
that adheres to the vessel walls. Eventually, blood flow is blocked. These
atherosclerotic changes are indistinguishable from atherosclerotic changes in
people without diabetes, but they tend to occur more often and at an earlier
age in diabetes. Coronary artery disease, cerebrovas-cular disease, and
peripheral vascular disease are the three main types of macrovascular
complications that occur more frequently in the diabetic population.
infarction is twice as common in diabetic men and three times as common in
diabetic women. There is also an in-creased risk for complications resulting
from myocardial in-farction and an increased likelihood of a second myocardial
infarction. Coronary artery disease may account for 50% to 60% of all deaths in
patients with diabetes. One unique feature of coronary artery disease in
patients with diabetes is that the typi-cal ischemic symptoms may be absent.
Thus, patients may not experience the early warning signs of decreased coronary
blood flow and may have “silent” myocardial infarctions. These silent
myocardial infarctions may be discovered only as changes on the
electrocardiogram. This lack of ischemic symptoms may be sec-ondary to
autonomic neuropathy (see below).
blood vessels are similarly affected by accelerated ath-erosclerosis. Occlusive
changes or the formation of an embolus elsewhere in the vasculature that lodges
in a cerebral blood vessel can lead to transient ischemic attacks and strokes.
People with di-abetes have twice the risk of developing cerebrovascular
disease, and studies suggest there may be a greater likelihood of death from
cerebrovascular disease in patients with diabetes. In addition, recovery from a
stroke may be impaired in patients who have elevated blood glucose levels at
the time of and immediately after a stroke. Because symptoms of cerebrovascular
disease may be similar to symptoms of acute diabetic complications (HHNS or
hypoglycemia), it is very important to rapidly assess the blood glucose level
(and treat abnormal levels) in patients reporting these symptoms so that
testing and treatment of cerebrovascular disease (stroke) can be initiated if
changes in the large blood vessels of the lower extremities are responsible for
the increased incidence (two to three times higher than in nondiabetic people)
of occlusive peripheral
researchers continue to investigate the relation between diabetes and
macrovascular diseases. The main feature unique to diabetes is an elevated
blood glucose level; however, a direct link has not been found between
hyperglycemia and atherosclerosis. Although it may be tempting to attribute the
increased prevalence of macrovascular diseases to the increased prevalence of
certain risk factors (eg, obesity, increased triglyceride levels,
hyperten-sion) among patients with diabetes, there is a higher-than-expected
rate of macrovascular diseases among patients with diabetes when compared with
nondiabetic patients with the same risk factors (ADA, Management of
Dyslipidemia in Adults With Diabetes, 2003). Thus, diabetes itself is seen as
an independent risk factor for the development of accelerated atherosclerosis.
Other potential factors that may play a role in diabetes-related
atherosclerosis include platelet and clotting factor abnormalities, decreased
flexibility of red blood cells, decreased oxygen release, changes in the
arterial wall related to hyperglycemia, and possi-bly hyperinsulinemia.
of macrovascular complications involves preven-tion and treatment of the
commonly accepted risk factors for ath-erosclerosis. Diet and exercise are
important in managing obesity, hypertension, and hyperlipidemia. In addition,
the use of med-ications to control hypertension and hyperlipidemia may be
in-dicated. Smoking cessation is essential. Control of blood glucose levels may
reduce triglyceride levels and can significantly reduce the incidence of
macrovascular complications do occur, treatment is the same as with nondiabetic
patients. In addition, patients may re-quire increased amounts of insulin or may
need to switch from oral antidiabetic agents to insulin during illnesses.