The cardiovascular system (CVS) comprises the heart and blood vessels (arteries, veins and capillaries).
The arteries carry blood from the heart to the organs and tissues, and the veins return blood to the heart.
The capillaries are tiny vessels in which there is exchange of gases, nutrients and waste materials.
Damage to the arteries and veins is called macrovascular disease, while damage to the capillaries is called microvascular disease.
Fatty materials, like cholesterol, when deposited on the blood vessel walls (called a plaque), reduce the space for blood to flow. If the plaque ruptures, a clot is formed to repair the damage.
With the passage of time, the vessels lose their elasticity. This contributes to the development of high blood pressure, which causes more damage to the blood vessels.
The clot can also break away from the artery wall and travel along the artery until it reaches a part too narrow for it to pass through and causes a partial or total blockage of that section.
This results in deprivation of oxygen and nutrients to the part of the body supplied by the artery beyond the blockage. This is the mechanism for heart attacks and strokes.
The narrowing can affect medium-sized arteries in the arms and legs, a condition called peripheral arterial disease (PAD). PAD leads to intermittent pain in the part of the limb beyond the narrowing.
The blood vessels can be damaged by high blood glucose, high blood pressure, high blood cholesterol and smoking.
The clinical features of heart disease include chest pain or discomfort; pain or discomfort in the arms, back, jaw or neck; difficulty breathing; sweating; indigestion or nausea; light-headedness; and tiredness or fatigue. The symptoms may come and go.
Chest pain that does not disappear after resting may indicate a heart attack. If diabetes has caused nerve damage, heart attacks may be painless.
Heart failure occurs when the heart becomes less able to pump blood. It may be caused by heart attack, high blood pressure or coronary artery disease.
The clinical features of heart failure include difficulty breathing, weakness, nausea, tiredness, and swelling of the feet and ankles.
Peripheral artery disease
PAD is due to the narrowing or blockage of medium-sized blood vessels by plaques in the legs and arms. It is associated with an increased risk of heart attack or stroke. It is estimated that one in three diabetics above 50 years of age have PAD.
The risk is increased further by high blood pressure, high blood cholesterol, overweight, physical inactivity, smoking, age above 50 years, and previous or family history of heart disease, heart attack or stroke.
Many with PAD have no symptoms. The clinical features are leg pain when walking or exercising, which disappears on resting, numbness or coldness in the lower legs or feet, and slow healing of infections in the feet or legs.
A stroke occurs when there is sudden interruption in the blood supply to a part of the brain. The majority of strokes are due to blockage of a blood vessel in the brain or neck by a blood clot.
Diabetics have a 1.5 times higher risk of getting a stroke compared to non-diabetics. The risk is increased further by heart disease, high blood pressure, high blood LDL cholesterol, overweight, physical inactivity, smoking, age above 50 years, and previous or family history of stroke or transient ischaemic attack (TIA or mini-stroke).
The clinical features of a stroke depend on the part of the brain affected. This includes difficulty with movement; pain; weakness in the limbs; numbness; difficulty talking; visual difficulties; dizziness; loss of balance; headache; and problems with thinking, speaking or remembering.
Although the features are temporary in TIA, the risk of stroke in the future is increased in all who have had a TIA.
There are several measures that diabetics can take to prevent cardiovascular disease.
The goal should be to keep the blood glucose, blood pressure and blood cholesterol within the target range agreed to with the attending doctors and nurses.
These parameters should be checked at least once a year, or more frequently, if the doctors advise so.
Other preventive measures include eating a healthy, balanced diet, being physically active, maintaining a healthy weight, taking medicines as prescribed, and smoking cessation.
Medical attention should be sought as soon as possible if there is any chest pain, intermittent pain when walking, erectile dysfunction or signs of a TIA or stroke.
Even if one has heart disease or have had a heart attack or stroke, there are preventive measures that can be taken to reduce the risk of another heart attack or stroke.
These measures have been given the mnemonic ABC.
A stands for HbA1C estimation, which provides information about the average blood glucose levels for the preceding three months, and is an indicator of diabetic control.
B stands for blood pressure, which, if raised, makes the heart work much harder than it should, thereby overburdening it.
C stands for cholesterol. Whilst HDL cholesterol protects heart function, LDL cholesterol blocks the arteries. Raised triglycerides increase the risk of a heart attack and/or stroke. The objective is to get the LDL cholesterol as low as possible.
The doctor will advise on the approach, which includes a healthy diet, maintenance of a healthy weight, medicines, and sometimes, even surgery.
Diabetes is not an impossible condition to manage. With good control of blood glucose, blood pressure and blood cholesterol, many of its complications, particularly cardiovascular disease, can be prevented.
Dr Milton Lum is a member of the board of Medical Defence Malaysia. The views expressed do not represent that of any organisation the writer is associated with. The information provided is for educational and communication purposes only and it should not be construed as personal medical advice. Information published in this article is not intended to replace, supplant or augment a consultation with a health professional regarding the reader’s own medical care. The Star disclaims all responsibility for any losses, damage to property or personal injury suffered directly or indirectly from reliance on such information.