Diabetes and Kidney Disease (cont.)
Effects of High Blood Pressure
High blood pressure, or hypertension, is a major factor in the development of
kidney problems in people with diabetes. Both a family history of hypertension
and the presence of hypertension appear to increase chances of developing kidney
disease. Hypertension also accelerates the progress of kidney disease when it
already exists.
Blood pressure is recorded using two numbers. The first number is called the
systolic pressure, and
it represents the pressure in the arteries as the heart
beats. The second number is called the diastolic pressure, and it represents the
pressure between heartbeats. In the past, hypertension was defined as blood
pressure higher than 140/90, said as “140 over 90.”
The ADA and the National Heart, Lung, and Blood Institute recommend that
people with diabetes keep their blood pressure below 130/80.
Hypertension can be seen not only as a cause of kidney
disease but also as a result of damage created by the disease. As kidney disease
progresses, physical changes in the kidneys lead to increased blood pressure.
Therefore, a dangerous spiral, involving rising blood pressure and factors that
raise blood pressure, occurs. Early detection and treatment of even mild
hypertension are essential
for people with diabetes.
Preventing and Slowing Kidney Disease
Blood Pressure Medicines
Scientists have made great progress in developing
methods that slow the onset and progression of kidney disease in people with
diabetes. Drugs used to lower blood pressure can slow the progression of kidney
disease significantly. Two types of drugs, angiotensin-converting enzyme (ACE)
inhibitors and angiotensin receptor blockers (ARBs), have proven effective in
slowing the progression of kidney disease. Many people require two or more drugs
to control their blood pressure. In addition to an
ACE inhibitor or an ARB, a
diuretic can also be useful. Beta blockers, calcium channel blockers, and other blood pressure drugs
may also be needed.
An example of an effective ACE inhibitor is lisinopril
(Prinivil, Zestril), which doctors commonly prescribe for treating kidney
disease of diabetes. The benefits of lisinopril extend beyond its ability to
lower blood pressure: it may directly protect the kidneys' glomeruli. ACE
inhibitors have lowered proteinuria
and slowed deterioration even in people with diabetes who did not have high
blood pressure.
An example of an effective ARB is losartan (Cozaar),
which has also been shown to protect kidney function and lower the risk of
cardiovascular events.
Any medicine that helps patients achieve a blood pressure target of 130/80 or
lower provides benefits. Patients with even mild hypertension or persistent
microalbuminuria should consult a health care provider about the use of
antihypertensive medicines.
Moderate-protein Diets
In people with diabetes, excessive consumption of protein may be harmful.
Experts recommend that people with kidney disease of diabetes consume the
recommended dietary allowance for protein, but avoid high-protein diets. For people with greatly
reduced kidney function, a diet containing reduced amounts of protein may help
delay the onset of kidney failure. Anyone following a reduced-protein diet
should work with a dietitian to ensure adequate nutrition.
Intensive Management of Blood Glucose
Antihypertensive drugs and low-protein diets can slow chronic kidney disease. A third treatment,
known as intensive management of blood glucose or glycemic control, has shown
great promise for people with diabetes, especially for those in the early stages
of chronic kidney disease.
The human body normally converts food to glucose, the simple sugar that is
the main source of energy for the body's cells. To enter cells, glucose needs
the help of insulin, a hormone produced by the pancreas. When a person does not
make enough insulin, or the body does not respond to the insulin that is
present, the body cannot process glucose, and it builds up in the bloodstream.
High levels of glucose in the blood lead to a diagnosis of diabetes.
Intensive management of blood glucose is a treatment regimen that aims to
keep blood glucose levels close to normal. The regimen includes testing blood
glucose frequently, administering insulin throughout the day on the basis of
food intake and physical activity, following a diet and activity plan, and
consulting a health care team regularly. Some people use an insulin pump to
supply insulin throughout the day.
A number of studies have pointed to the beneficial
effects of intensive management of blood glucose. In the Diabetes Control and
Complications Trial supported by the National Institute of Diabetes and
Digestive and Kidney Diseases (NIDDK), researchers found a 50 percent decrease
in both development and progression of early diabetic kidney disease in
participants who followed an intensive regimen for controlling blood glucose
levels. The intensively managed patients had average blood glucose levels of 150
milligrams per deciliter—about 80 milligrams per deciliter lower than the levels
observed in the conventionally managed patients. The United Kingdom Prospective
Diabetes Study, conducted from
1976 to 1997, showed conclusively that, in people with improved blood glucose
control, the risk of early kidney disease was reduced by a third. Additional
studies conducted over the past decades have clearly established that any
program resulting in sustained lowering of blood glucose levels will be
beneficial to patients in the early stages of chronic kidney disease.
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