What causes complications?

Persistant high blood glucose over an extended period of time.

The development of diabetes complications may depend on how long you’ve had diabetes and on your diabetes management over the years. Keeping your blood glucose under tight control helps to prevent or delay complications.
However, some people are just more susceptible to long-term complications than others, of note:

  • People who have had diabetes for several years, may develop problems with damage to blood vessels and reduced blood flow to nerve endings.
  • Large Blood vessel damage (Macrovascular damage) may result in increased incidence of heart attack (Myocardial infarction) and stroke. Small blood vessel damage (Microvascular damage) causes problems with the tiny blood vessels to the Eyes, feet, Kidneys and nerve endings.

Helping Prevent complications

Have your diabetes management monitored regularly by hospital based diabetes team. Some diabetes monitoring checks are carried out for each visit e.g. HbA1c,  cholesterol level and blood pressure, some are done annually e.g. general wellbeing, dietetic, kidney, eyes and foot review.  You will get the chance to meet or arrange to meet with the dietitian for support. Always consult your doctor or another member of your diabetes care team, if you have any diabetes related problem.
Tips include:

  • Aim to maintain your diabetes under good control
  • Maintain good blood pressure
  • Maintain good cholesterol levels
  • Do not smoke
  • Be active
  • Maintain a healthy diet
  • Ask questions & keep informed


This is a measure of your blood glucose control over a period of the previous approx 6 -8 weeks. It is a very good indicator of your overall control of your condition despite the odd high or low readings you may have had during that time. The risk of developing problems related to diabetes long term is lessened if the HbA1c result is maintained at a good level.

Complications can include any of the following:

Macrovascular (Large blood vessels)
When you have diabetes it is essential that you monitor and manage all the factors that increase your risk of artery disease, as disease of the heart and circulatory system can be very serious.


As we get older, we all become more at risk of diseases occurring in our arteries. The walls of these arteries may become thickened by the build up of cholesterol and stiffened by the formation of scar tissue. This process is called ‘atherosclerosis’. Atherosclerosis tends to occur in localised patches. It may occur anywhere in the circulatory system, but certain arteries are more vulnerable. It is a problem because it restricts the flow of blood through the vessel, and because it increases the risk of blood clots in that vessel.

The risk

People with diabetes are at an increased risk of atherosclerosis if they do not maintain good blood sugar control. Risk is further increased by smoking, high blood pressure and high cholesterol levels. Unfortunately, diabetes often occurs together with high blood pressure and high cholesterol. Therefore, when you have diabetes it is essential that you monitor and manage all the factors that increase your risk of artery disease, as disease of the heart and circulatory system can be very serious.

High blood pressure

Your blood needs to be kept under pressure in order for it to flow through your vessels, but if the pressure is abnormally high this increases the risk of artery disease developing. Therefore, the higher your blood pressure, the greater your risk of heart disease, peripheral vascular disease and stroke, as well as of kidney damage. Blood pressure naturally increases with age. Unfortunately, people with diabetes have a greater likelihood of an increased blood pressure or ‘hypertension’.

How do I know if I have high blood pressure?

Most people with hypertension do not have any symptoms. The only way to know if your blood pressure is high is to have it measured by your doctor. Since blood pressure varies from minute to minute, several readings need to be taken over a few weeks to establish whether you really have hypertension.

Treating high blood pressure

You may be able to keep your blood pressure down by staying fit and by losing weight if you need to. Too much salt or alcohol can increase blood pressure so cutting down on these is a good idea. If you smoke, try to stop; smoking not only raises blood pressure, it also directly increases your risk of heart and circulatory disease. Many people with diabetes find they need to take regular medication to bring their blood pressure down to normal levels. There are many different kinds of medicines for blood pressure; these drugs are known as ‘antihypertensives’. If one kind doesn’t suit you, alternatives can usually be found.


It is likely that you will have heard the term ‘cholesterol’ in relation to heart disease. Cholesterol is a fat that is transported in the blood in small particles called ‘lipoproteins’. It has many important functions in the body. If the level of cholesterol in your blood is too high, excess cholesterol can become deposited in the artery walls directly contributing to the process of atherosclerosis. There are different types of lipoproteins, later some contribute to artery disease while others are actually beneficial. Your doctor will measure your total cholesterol level as well as the different types of lipoprotein to assess whether you are at risk of artery disease. Unfortunately, diabetes is often associated with high cholesterol. Your dietitian will advise you on diets that are low in cholesterol, but you may also need special medicines – ‘lipid-lowering drugs’ – to bring your cholesterol level down to normal.

Coronary artery disease

One group of arteries that are vulnerable to atherosclerosis are the ‘coronary’ arteries. These supply the heart with blood, and hence oxygen. If blood flow is restricted through these arteries, the heart muscle is starved of oxygen. This causes chest pain, referred to by doctors as ‘angina’. Angina is most likely to be suffered during exercise when the heart’s requirement for oxygen is high. Rest usually eases the pain. Persistent angina can be treated with drugs or surgical procedures. People with diabetes are at increased risk of coronary artery disease if their blood sugar, blood pressure and cholesterol are not well controlled, and many will eventually need to take treatments for heart disease. Some patients who develop angina or other forms of heart disease may be referred to a cardiologist – a specialist in heart disease.

Heart attack

Sometimes, a clot can form in a diseased coronary artery completely blocking the vessel. Doctors call this situation a ‘myocardial infarction’ or ‘MI’, but it is popularly known as a ‘heart attack’. Symptoms include prolonged, crushing chest pain, sweating, nausea, breathlessness and loss of consciousness. It is vitally important for people who are suspected of having a heart attack to be taken to hospital. With modern intensive medical care, most people experiencing a heart attack are expected to survive if they reach hospital soon enough. Afterwards, they may need to take medications to support their damaged heart.

Artery disease in the brain

Atherosclerosis may affect other arteries besides the coronary arteries. If arteries supplying the brain are affected, areas of the brain can be starved of oxygen resulting in black-outs or permanent damage – a stroke. Stroke is common in people with high blood pressure. The effects of a stroke are very variable, and depend on the areas of brain damage. Many different bodily functions can be affected and the severity of symptoms varies greatly. With rehabilitation, many people recover the functions that they lost with their stroke. Sadly, some people are permanently disabled, and some strokes are fatal.

Peripheral vascular disease

Atherosclerosis can also affect the large arteries supplying the lower limb muscles. If insufficient blood reaches the calf muscle, walking long distances can become painful, and the affected person must keep stopping to recover before they can continue. Doctors call this situation ‘intermittent claudication’. Sometimes drugs or a planned exercise program can help. Sadly, in some situations the limb receives insufficient blood to keep it alive and amputation becomes necessary. Keeping tight control of your blood sugar can decrease your risk of this dramatically.

Microvascular damage (Small blood vessels)

The complications described above relate to disease of the large arteries. However, if you have diabetes, the smaller blood vessels can also become damaged. This in turn can result in damage to the eyes, kidneys, feet, and teeth/gums.

Eyes and diabetic retinopathy

Below is an excellent video and Review by Sean Kirwan, Medical Scientist and Research Associate at UCD and ICON plc.

Diabetic Retinopathy from Sean Kirwan on VimeoThis 3D animated video was created by Sean Kirwan, Medical Scientist, during a Knowledge Exchange Dissemination Scheme (KEDS) with University College Dublin and ICON Firecrest, funded by the Health Research Board. Lead Pharmacologist was Sean Kirwan and 3D Graphic Designers included Carlos Tena and Tomás O’Sullivan of ICON Firecrest. Support Pharmacologist was Dr Paul Halley of ICON Firecrest. Dr Breandán Kennedy (UCD) and Dr Rosemarie Carew (ICON Firecrest) were project supervisors.

Review of Diabetes & Diabetic Retinopathy


Click on image to download


Diabetes is a condition where the body can’t use and store sugar properly and this can cause many health problems. Too much sugar in the blood can cause damage to blood vessels throughout the body, including the blood vessels in the eye. These eye changes are called diabetic retinopathy.
For more information please go to our retinopathy section or checkout this Retinopathy Factsheet

Kidneys (Nephropathy)

You are advised to have a regular assessment of your kidney function. This will involve a routine blood test and a urine test for microalbuminuria. This is usually done annually.
Microalbuminuria is tiny amounts of albumin (a protein) found in the urine. This indicates that your kidneys are not getting rid of waste products as effectively as they should. The presence of albumin acts as a warning sign that you are at increased risk of the long-term complication associated with diabetes, which can affect the kidneys. Good blood pressure management and good glucose management also assist in protecting the kidney. Your doctor may also have prescribed medication for blood pressure which also has a protective effect on the kidney.

Checkout this Nephropathy Factsheet.


For information on footcare and complications please click here for our footcare section, also checkout this factsheet on Wound Healing & Foot Ulcers.

Nerve endings: (Neuropathy)

Over the years, again particularly if diabetes control is poor problems may arise with nerve endings and blood flow that supplies the nerve endings through out the body. This may result in reduced sensation and or tingling or burning sensation to the hands and feet.
Problems related to nerve supply may also occur for some to the digestive tract, bladder, heart and other organs.

Checkout this Neuropathy Factsheet.

Erectile dysfunction (ED)

ED may occur for a variety of reasons including stress, alcohol and tiredness. ED however may also be related to poor glucose control reduced circulation, or damage to nerve endings. Should you be concerned you are urged to discuss this with your GP or diabetes team as there are many treatments available, along with support to aim improve your overall diabetes management as appropriate.
See also

Other useful factsheets:


All factsheets above have been provided by REDDSTAR. Funded by the European Commission’s FP7, REDDSTAR is a three year, 10 partner project that will comprehensively examine if mesenchymal stromal cells derived from bone marrow can safely control blood glucose levels while also alleviate damage caused by six diabetic complications. Please visit for more information