Diabetes And Circulatory Problems

People with diabetes, especially those with type 2 diabetes, are two to five times more likely to have problems with circulation to the heart, the legs, and the head when compared to individuals without diabetes. This is because diabetes predisposes a person to a condition called atherosclerosis. If you imagine a blood vessel as a water or drainage pipe, then atherosclerosis is buildup in the pipe narrowing the channel and impairing the flow. In the case of the blood vessel the buildup, called plaque, consists of a core of inflammatory cells, cholesterol, and lipids with a fibrous cap of smooth muscle cells (see Figure 3-1). The plaque can narrow the blood vessel, impairing blood flow. Occasionally the fibrous cap can rupture, and when this happens a blood clot forms, causing an acute blockage of the blood vessel. If the acute blockage happens in one of the blood vessels to the heart, it results in a heart attack. If it occurs in one of the blood vessels supplying brain tissue, it results in a stroke.

What is it about diabetes that predisposes a person to atherosclerosis? First, having high glucose levels for long periods can injure the cells lining the blood vessels, initiating the plaque buildup. Second, the high blood pressure and the elevated lipids frequently present in people with diabetes are known risk factors for plaque buildup. There are also other less well understood factors such as blood clotting factors and platelet function that are also altered in people with diabetes.

Even though people with type 1 diabetes generally do not have high blood pressure and high cholesterol problems, they can develop heart disease after many years. This is especially likely to occur if they have diabetic kidney disease.

Figure 3-1 Artery Containing Plaque Buildup

Abnormal blood flow


Abnormal blood flow


Lipid core

Fibrous cap

Lipid core

Fibrous cap

Source: www.nhlbi.nih.gov/health/dci/diseases/cad/cad_causes.html.

Diabetes and the Heart

Diabetes affects the heart in a number of different ways. Atherosclerosis of the coronary arteries (coronary artery disease) can limit the delivery of nutrients to the heart muscle. When this occurs you can develop chest pain with exercise (angina). If there is acute blockage then this is referred to as a heart attack or myocardial infarction.

Heart failure is more common in people with diabetes. Many times it occurs because of heart muscle damage following a heart attack. Long-standing high blood pressure associated with diabetes is also an important cause. It is now also recognized that high glucose levels themselves damage the heart muscles. People with heart failure feel tired, short of breath at rest and/ or on exertion, and have leg swelling.

It is therefore important to have a physical checkup to rule out heart disease before you begin an exercise program. See Chapter 9 for more on exercising with diabetes.

Diabetes and Brain Circulation

Interruptions of blood supply to the brain due to atherosclerosis can lead to transient or permanent neurological abnormalities—referred to as a transient ischemic attack (TIA) or stroke. Older people with diabetes have an increased risk of memory problems, and it is thought that in at least some of them, this is a result of small strokes.

Diabetes and Circulation to the Legs

When there is atherosclerosis in the blood vessels supplying the leg, the decrease in the blood flow can lead to cramps and pain (typically in the calves) when exercising. This is called intermittent claudication, and the pain is relieved by rest. If the blood supply is severely impaired, there is pain even at rest. Eventually, the lack of blood flow can cause tissue death, especially of the toes (gangrene). Cigarette smokers are particularly at risk.

Prevention of Circulatory Problems

Circulatory problems, especially heart disease, are the major cause of premature death in people with diabetes, and prevention of these problems is a central goal in the treatment of diabetes. You can take a number of steps to reduce your risk of heart disease and circulatory problems:

• Improve glucose control. The target levels are described in Chapter 5.

Lower blood pressure. I have already discussed in the "Diabetic Kidney Disease" section earlier in this chapter the importance of controlling blood pressure. The treatment goal is to get the systolic blood pressure (top number) below 130 mm Hg and the diastolic blood pressure (bottom number) below 80.

• Take aspirin. Clinical studies show that aspirin reduces the risk of heart attacks and stroke. Aspirin works by making platelets (the cells in the blood that are responsible for blood clotting) less sticky. Recent studies indicate that lower doses are just as effective as higher doses, so low-dose aspirin therapy (a 75-81 mg dose once a day) is recommended if you already have heart disease or circulatory problems. If you cannot tolerate aspirin because of allergic reaction or another reason, your doctor may prescribe a medicine called clopidogrel (Plavix), which also makes the platelets less sticky. Individuals with type 1 and 2 diabetes without heart disease or circulatory problems should also take low-dose aspirin therapy if they have a strong family history of heart disease; if they have kidney damage, high blood pressure, or lipid problems; if they are smokers; or if they are older than forty years.

Stop smoking. Smoking increases the risk of both macrovascular and microvascular damage in people with diabetes.

• Improve your lipid profile. People with type 2 diabetes frequently have abnormalities of their lipid profile—a collective term for cholesterol, triglycerides, HDL cholesterol, and LDL cholesterol levels. Almost all people with type 2 diabetes and many with type 1 diabetes need to take medicines for the lipid abnormalities.


Children and Aspirin

Individuals younger than twenty-one years should not take aspirin, because if they are taking it and they get influenza, they are at higher risk of developing a very serious illness called Reye's syndrome. If you are under twenty-one years of age, you should consult your doctor before taking aspirin.


The Function of Cholesterol

Cholesterol is an important molecule in the structure of cell membranes and nerve sheaths and is a building block for a number of important hormones. The body absorbs cholesterol from the food we eat, and it also makes new cholesterol in the liver.

Triglycerides are an energy source of the body made in the intestine and the liver. They consist of three fatty acid chains combined with glycerol. Cholesterol and triglycerides combine with proteins to form lipoprotein particles that circulate in the blood. These particles include the following:

• Chylomicrons

• Very low-density lipoproteins (VLDL)

• Low-density lipoproteins (LDL), which deliver cholesterol to all the cells in the body

• High-density lipoproteins (HDL), which are made in the liver and intestines— HDL cholesterol is known as the good cholesterol

In people with diabetes, the levels of triglycerides are frequently too high and the levels of HDL are too low. In addition, people with diabetes tend to have a form of LDL particles called small, dense LDL, which can abnormally collect in the blood vessel walls and cause atherosclerosis. Research has shown that correcting these lipid abnormalities in people with diabetes reduces the development of atherosclerosis. The goals of treatment are to

• Lower the LDL cholesterol to at least below 100 mg/dl but ideally to 60 to 70 mg/dl

• Lower the triglyceride level to below 150 mg/dl

• Raise the HDL cholesterol to more than 40 mg/dl in men, and to more than 50 mg/dl in women

There are a number of lipid-lowering medicines that a doctor may prescribe. These are summarized in Table 3-4.

Table 3-4 Lipid-Lowering Medicines

Name of Medicine

Examples (Generic and Trade Names)

How It Affects the Lipid Profiles

HMG-CoA reductase inhibitors or statins

Lovastatin (Mevacor) Pravastatin (Pravachol) Simvastatin (Zocor) Fluvastatin (Lescol) Atorvastatin (Lipitor) Rosuvastatin (Crestor)

Mainly lower total cholesterol and LDL cholesterol


Gemfibrozil (Lopid) Fenofibrate (Tricor)

Lower triglycerides. Modest lowering of total cholesterol and LDL cholesterol. Modest increase in HDL cholesterol.

Omega-3 fatty acids

Nutritional supplement

Lower triglycerides. Modest increase in HDL cholesterol.

Niacin (vitamin B3)

Nutritional supplement

Lowers total cholesterol, LDL cholesterol, and triglycerides. Raises HDL cholesterol.


Ezetimibe (Zetia)

Lowers total cholesterol and LDL cholesterol.

Bile acid resins

Cholestyramine (Questran) Colestipol (Cholestid) Colesevelam (Welchol)

Lower total cholesterol and LDL cholesterol; may raise triglycerides.



There is a genetic defect in some people in whom the triglyceride level can go very high: in the 1,000s (instead of less than 150 mg/dl). This is a serious condition that can lead to an inflammation of the pancreas (pancreatitis) and requires hospitalization. The treatment is to stop eating until the triglycerides fall, control the diabetes, and also take one of the fibrate medicines.

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