Even when diabetes is well controlled, it raises the risk of other conditions such as heart disease, and poorly controlled diabetes can lead to serious complications.1-3
The good news is that diabetes prevention has greatly improved, leading to a drop in the rates of five major complications - including death - from 1990-2010 in the US.4
Causes of diabetes complications
High blood glucose levels are damaging to blood vessels and can increase the likelihood of them narrowing through atherosclerosis. This damage also leads to poor supply of blood to nerves.1-3
Poorly controlled hyperglycemia persisting for years can lead to complications affecting small blood vessels (microvascular complications), large blood vessels (macrovascular complications) or both.2
The process by which vascular disease develops is complex and occurs via numerous pathways that scientists continue to investigate.5
What complications are caused by diabetes?
Microvascular complications - those resulting from damage to small blood vessels - are the most common complications of diabetes and include:2
- Retinopathy - disease of the eye
- Nephropathy - disease of the kidneys
- Neuropathy - disease of the nerves.
Macrovascular complications - those resulting from damage to large blood vessels - include:2
- Angina pectoris and heart attack
- Transient ischemic attacks and strokes
- Peripheral arterial disease.
People with diabetes should go for regular professional eye checks.
Diabetic retinopathy is an eye complication caused by disease of the tiny blood vessels supplying the retina (the light-sensitive back of the eye).2,3
Early detection and preventive action are important. As symptoms do not appear before damage is done, anyone with diabetes - whether type 1 or type 2 - should have their eyes regularly checked by an optometrist or ophthalmologist.2,3,6
Most people with diabetic retinopathy do not lose their vision, but blindness is nonetheless a risk. The key to prevention is tight control over blood sugar levels. Interventions are also available for diabetic retinopathy, such as laser photocoagulation.2,6
Diabetic nephropathy - kidney or renal disease - is another complication caused by damage to small blood vessels.2
Diabetes is the cause of most cases of the most serious kidney disease - end-stage renal disease.1 Nephropathy can also appear at other stages, from renal insufficiency through to chronic renal failure. There is a progressive decline in kidney function in terms of the glomerular filtration rate.2
Nephropathy is diagnosed by urine test and the primary treatment - as with other diabetes complications - is tight control of blood sugar levels. In addition, blood pressure treatment with drugs may be needed.2
Diabetic neuropathy - a disease of nerves - is also a complication caused by damage to small blood vessels. In this case, it involves capillaries supplying nerves.2
Diabetes can cause nerve damage in the feet. Wounds can go unnoticed and fail to heal properly.
Complications affecting the foot - often referred to as "diabetic foot" - result from neuropathy, nerve damage that causes tingling sensations, burning or stinging pain, weakness or loss of feeling.2,6 The nerves become damaged due to restricted blood supply.2
The phenomenon can also affect the hands, but it is the feet that are most commonly affected. Because of the loss of sensation for heat, cold or pain, and a lack of attention given to the feet, they are at risk from injury, wounds, blisters or ulcers going unnoticed. If left unnoticed, this condition can lead to infection and even gangrene and potential amputation.2,3,7
Nerve damage leads to skin changes, making the foot dry and prone to cracking or peeling.2,7 Poor circulation to the feet caused by vessel narrowing can also mean that any infections or wounds heal less readily.7
The key to preventing foot complications is to monitor the feet so that problems are spotted at the first opportunity. Seeking medical attention for any problems is important, as is getting the feet checked by a health care professional, such as a podiatrist, at least annually.2 Other practical measures include:3
- Keeping the feet clean and dry
- Ensuring the nails are well-maintained
- Wearing socks and shoes that fit comfortably and do not rub or squeeze the feet.
Disease of the large blood vessels caused by diabetes can lead to angina, transient ischemic attacks or stroke, heart attack and peripheral arterial disease. Alongside microvascular disease, macrovascular disease also contributes to the risk of the heart disease cardiomyopathy.2
Screening, history and physical examination diagnose macrovascular disease, and treatment includes tight control of blood sugar levels as well as lipid- and blood pressure-lowering therapies. Other strategies include smoking cessation, aspirin and drugs known as ACE inhibitors.2
Adults with diabetes are two-to-four times more likely to have heart disease or a stroke than those without diabetes. A number of risk factors in people with diabetes contribute to macrovascular complications:1
- High blood pressure
- Abnormal cholesterol and high triglyceride levels
- Lack of physical activity
Prevention of diabetes complications
All the potential complications of diabetes can be prevented or controlled with tight glycemic control, which means keeping HbA1C levels below 7%.2
Measures to keep control of glucose levels, in addition to drugs or insulin treatment, include exercise and diet. Additionally, keeping control of blood pressure and lipid levels helps to prevent complications of diabetes.2
As discussed above, close monitoring of health so that potential complications are spotted at the first opportunity is also a preventive measure, including specific checks for the eyes and feet.