Diabetes is a major risk factor for heart disease or cardiovascular disease.

What exactly does this mean for you and me?

Hearing the words heart disease can cause fear and uncertainty. But “heart disease” isn’t actually one single condition. It’s an umbrella term that covers a range of different conditions affecting the heart and blood vessels.

This four-part section aims to help make some sense of the terminology, explain how diabetes fits into the picture, and explore what you can do to reduce your risk.

Part 1 – Introduction
An introduction to the heart, the terminology used, risk factors and cardiovascular risk assessment.

Part 2 – Coronary Heart Disease
What happens when the arteries supplying the heart become damaged or narrowed.

Part 3 – Angina
Why reduced blood flow to the heart can cause chest pain, and what angina means.

Part 4 – Heart Attack
What happens when the blood supply to part of the heart muscle becomes blocked.

Part 3 – The Pain of Angina

How do you know if you have coronary heart disease? Frequently the first signs are mild or moderate attacks of angina – which is severe pain in the chest usually when exercising or moving. Angina is technically not a disease in itself, it is a symptom of heart disease. Nevertheless, it is common to refer to it as a ‘condition’ associated with coronary heart disease.

This page looks at the ins and outs of angina, with special consideration towards having diabetes.

What is ‘Angina’?

Angina is the name given to the chest pain experienced when the heart muscle is not receiving an adequate blood supply, and is being starved of oxygen. The pain may be associated with periods of exercise or minor exertion – angina is caused by taxing the heart beyond its limits.

Angina is most commonly associated with coronary artery disease. Narrowing of the arteries that supply the heart itself can reduce the available blood supply to the heart muscle. If the heart muscle is deprived of blood, it is also deprived of oxygen and nutrients.

When the supply of oxygen to the heart muscle is not sufficient, angina pain results.

Normally, the heart muscle will get its life-giving supply inbetween ‘beats’. If the heart rate increases, the oxygen supply to the heart itself is therefore reduced further. Thus, during periods of exercise or stress, when the heart beats faster, someone with narrowed coronary arteries are more likely to suffer from angina.

*Angina that occurs after eating is known as ‘postprandial angina‘ and can be mistaken for indigestion. This happens because the heart has to work harder after a large meal in order to for digestion to take place. Beware of taking a walk straight after a large meal!

Stable Angina

Angina pain that occurs ‘predictably’ over weeks or months is referred to as ‘stable angina‘. ‘Predictably’ means that you can predict that it will happen if you exert yourself or push yourself over a certain limit. Equally, you can be confident that it will respond to GTN or rest in a predictable way (see below and Appendix A for more on GTN or nitroglycerin).

Stable angina is a serious condition, and should not be ignored. You may be able to manage it adequately – for the time being – but pay attention to lifestyle fators and take any prescribed medication regurlary in order to limit progression of the disease.

Unstable Angina

Angina pain that is more frequent, more intense, occurs during periods of rest or with only minimal exertion, and which increases in severity is referred to as ‘unstable angina‘. Unstable angina should be considered a medical emergency. Although it may be mistaken for a heart attack, it warrants emergency medical care. Unstable angina carries a high risk of heart attack.

If angina pain lasts longer than 20 minutes or is not relieved by nitrate tablets or spray (see below), if you are breathless, feeling nauseous, or sweating profusely, then call for an ambulance. Take 300mg (Check dose NZ guidelines) of Aspirin; this may help to reduce the damage of a heart attack (see Part 4).

Treatments for Angina

Medications prescribed for angina may include the following:

• a beta-blocker
• low-dose aspirin
• blood pressure lowering drug
• a lipid-loweriung drug
• a nitrate

Treatment specific for angina is aimed to increase the blood supply to the heart muscle.

GTN (Nitroglycerin)

Glyceryl trinitrate (GTN) is sometimes called ‘nitroglycerin’ – both names refer to the same drug. Nitrates relax the muscles in the walls of blood vessels, and therefore widen the coronary arteries, helping blood to flow if the arteries are narrowed. Nitrates are useful for relieving angina pain, and for preventing angina pain in ‘predictable’ circumctances (e.g. when exercising). Nitrates may be valuable in preventing angina in the long term as well, but note that they may become less effective if they are used continuously over a long period.

GTN tablets are put under the tongue and should be allowed to dissolve. They are not effective if you swallow them. They lose their strength quite quickly, so always keep a fresh supply to hand.

GTN spray comes in an aerosol form and is sprayed under the tongue. Always check the use by date and keep a fresh supply to hand.

Oral nitrates are tablets taken by mouth and swallowed. These are usually isosorbide mononitrate in a slow-release preparation.

Thrombolytic therapy

Thrombolytic therapy employs ‘clot-busting’ drugs to dissolve blood clots that may be obstructing blood flow in a major artery, such as a coronary artery. A drug such as streptokinase or tPA (tissue plasminogen activator) may be injected into the blocked coronary artery, using angiography to guide the process. Clot-busting drugs may also be given intravenously, sometimes along with heparin (a blood thinner).

Angioplasty

Percutaneous transluminal coronory angioplasty (PTCA) or ‘balloon’ angioplasty is a medical procedure that uses a balloon to squeeze open the narrowed blood vessels in the heart. It is usually performed under a local anaesthetic and takes the same approach as an angiogram to access the heart.

A thin tube (catheter) is usually inserted into an artery at the top of the leg, towards the groin area (occasionally an artery at the wrist or elbow is used). The catheter is guided up to the heart and into the narrowed vessel. A fine wire is then passed along the catheter, and, once it is across the narrowing, a balloon is inflated. This pushes the narrowed part of the artery outwards, widening the lumen and increasing the space for blood to flow through.

The success of the procedure can be determined by injecting a dye solution which enables blood flow to be easily visualised (you can usually watch the process yourself on the screen).

Angioplasty may take anything from 5 or 10 minutes up to an hour to perform, depending on the individual case. You may need to stay overnight at the hospital, but you should be able to go home the following day.

Angioplasty is successful only in about 60-70 per cent of cases. In about 30-40 per cent of cases, the arteries have become narrowed again within 6 months or so (this process is called ‘restenosis‘). For these people, repeat angioplasty usually neds to be performed. Sometimes a coronary stent may provide a better alternative (see below).

Stents

A stent is a metal mesh frame that is inserted into the narrowed coronary artery with the help of a ballon in a similar fashion to that described above. This provides a permanent mechanical way of holding the artery open in order to improve blood flow.

Scarring at the site of stent insertion can be a problem, particularly when tissue grows through the mesh of the stent; this can lead to renarrowing of the blood vessel.

Atherectomy

Atherectomy is the excision and removal of plaque from atherosclerotic lesions in coronary arteries. It may be performed instead of, or in addition to, balloon angioplasty.

Bypass Surgery

If many arteries are narrowed, or if restenosis has complicated angioplasty or stent insertion (see above) then a coronary bypass operation is usually the best option in order to significantly improve blood supply to the heart muscle.

A coronary artery bypass graft (CABG, pronounced “cabbage!”)

Page updated: August 2026