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Diabetes and heart disease: A fatal link

  • Story Highlights
  • 2 out of 3 people with type I or II diabetes will die from a heart attack or stroke
  • Diabetics must watch their blood sugar, blood pressure and cholesterol levels
  • Exercise, diet and not smoking also can help diabetics stay healthy
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By Ann Curley
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Editor's note: Ann Curley is the assignment manager for the CNN Medical News unit and a type I diabetic.

Your doctor can help you monitor blood sugar levels and cholesterol levels through a simple blood test.

(CNN) -- Diabetes is the fifth-leading killer of Americans, according to the American Diabetes Association. A sobering two out of three people with type I or type II diabetes will die from a heart attack or stroke -- the combined leading causes of death among diabetics.

There are few diabetics who haven't heard horror stories about patients who have lost limbs or gone blind because of poor disease control.

Keeping a trio of factors -- blood glucose, blood pressure and cholesterol levels -- within recommended ranges is key to reducing the risk for diabetes-related complications such as heart attacks, strokes and peripheral vascular disease, which occurs when blood flow to the limbs is impaired.

Health professionals often tell diabetics to mind their "ABCs."

A stands for A1C

This is an important blood test, officially called glycolated hemoglobin, or HbA1C. The A1C test is a reading of the average blood glucose values for the past two or three months.

A little science lesson: Hemoglobin is a protein in red blood cells that carries oxygen to all the body cells. When diabetes is uncontrolled, too much sugar, or glucose, is in the blood. The extra glucose enters the red blood cells and sticks to -- or glycates -- the hemoglobin. The more excess glucose, the more sugar that sticks to the hemoglobin. And these clumps of glucose and hemoglobin can be measured as a percentage of the blood -- the A1C reading.

The test is a bit of a lie detector for glucose control -- your A1C will tell your doctor how much extra sugar has been flowing around in your blood. A nondiabetic will have a normal A1C of 4 to 6 percent, which works out to an average blood sugar of about 65-135 milligrams per deciliter (mg/dL) of blood. The higher the number, the more glucose that is in the blood. A well-controlled diabetic should aim for an A1C of less than 7 percent, which is an average blood sugar of about 170 mg/dL.

B stands for blood pressure

High blood pressure, or hypertension, is also known as "the silent killer" because it usually has no symptoms. High blood pressure causes the heart to work harder to pump blood, straining the heart, damaging blood vessels and increasing the risk of heart attack, stroke, eye and kidney problems.

Target healthy blood pressure for most people, including diabetics, is below 130/80 millimeters of mercury (mm/Hg), a scientific measure of pressure. The top number, the systolic pressure, represents the pressure generated by the heart as it pumps blood into the body. The lower number, the diastolic pressure, represents the pressure between heartbeats when the heart is resting. A systolic pressure over 140 is considered high, and a diastolic pressure over 90 is considered high. It's important to have your blood pressure checked several times per year.

C is for cholesterol

This is the waxy substance found in the fats, or lipids, in the bloodstream and in all body cells. Healthy blood fat levels are key to fighting heart disease.

Healthy targets for cholesterol

Total cholesterol: Below 200 milligrams per deciliter (mg/dL)

LDL ("bad") cholesterol: Under 100 mg/dL

HDL ("good") cholesterol:

For men: above 40 mg/dL

For women: above 50 mg/dL

Triglycerides: Under 150 mg/dL

Cholesterol is transported in the body by carriers called lipoproteins. Low density lipoproteins, or LDL, carry most of the cholesterol.

An excess of LDL in the blood can cause fatty material to deposit inside blood vessels, clogging and hardening them.

This can lead to heart disease, stroke and other circulatory problems -- and is why LDL is often called the "bad" type of cholesterol.

High density lipoproteins, or HDL, also transport cholesterol but seem to work to reduce the deposits of LDL cholesterol. HDL is often called "good" cholesterol because of how it works against LDL cholesterol.

Triglycerides are a byproduct derived from calories not immediately used as energy, and they are stored in fat cells. Hormones release triglycerides from fat tissue.

High triglycerides signal uncontrolled blood glucose levels in diabetics, and they can signal coronary artery disease in some people.

How insulin works

It can't be stressed enough that the key to well-controlled diabetes begins and ends with careful glucose management.

When we eat food, most of it is broken down into glucose, the body's main source of fuel. Glucose enters the bloodstream and, in a nondiabetic, the pancreas produces the hormone insulin that opens the "doors" of cells, allowing glucose to enter and provide energy.

In diabetics, either the pancreas doesn't make enough insulin to open the cell doors, or the cells in the muscles, liver and fat can't properly process the insulin to open the doors, or both.

The result: High glucose levels circulate in the bloodstream, unable to get through the cell doors and provide energy to the hungry cells.

This is where problems begin. High blood glucose levels circulating through the body without being turned into cellular energy will begin to damage the body.

"When the unfed cells are starved for their metabolic fuel, glucose, they become damaged and eventually die," explained cardiovascular surgeon Dr. Alon S. Aharon of University Hospitals of Cleveland/Case Western.

"When the cells die, this may cause damage to the heart, brain and kidneys, among other organs."

High glucose levels also affect blood fat levels. High glucose can prevent the HDL, or "good" cholesterol from binding to and processing other cholesterol and fats properly, leading to increased fat deposits in blood and blood vessels. This increases the risk for stroke, heart attack and peripheral vascular disease.

"A large proportion -- a third to a half -- of the patients with heart disease and peripheral vascular disease have poorly controlled diabetes, which greatly impacts not only their long-term survival but their quality of life because of potential limb loss, kidney damage, and debilitating heart disease," Aharon said.

The good news is that heart disease doesn't have to be a complication of diabetes. Controlling glucose levels, blood pressure and cholesterol will decrease the risk factors for heart disease and stroke.

And those actions, combined with exercise, a healthy diet and not smoking, are a recipe for good body and heart health. E-mail to a friend E-mail to a friend

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