Diabetes Complications

Diabetic complications can be grouped into two categories: acute and chronic. The complications detailed here are not intended to represent an exhaustive list and it should be understood that further complications do exist.

Acute complications, those that occur suddenly, are directly related to blood glucose levels, can be very severe and may quickly lead to coma or death. Acute complications include hypoglycaemia, diabetic ketoacidosis (common in type 1 diabetes and associated with fatty acid breakdown due to low blood glucose), and hyperglycemic hyperosmolar non-ketotic syndrome (HHNS - usually associated with insulin deficiency and dehydration).¹

Chronic complications are those which occur over a longer period of time and involve changes in blood vessels, tissue and organs. Persistent hyperglycaemia damages blood vessels which may lead to many disorders, such as cardiovascular and cerebrovascular disease. Damage to blood vessels within the eye can result in diabetic retinopathy and ultimately blindness. Pathological changes within the kidneys cause diabetic nephropathy and kidney failure, while damage to peripheral nervous tissue will ultimately lead to diabetic neuropathy.² A combination of vascular and neurological damage will result in erectile dysfunction.²

Effective prevention of diabetes-related complications requires close monitoring of the progress of the disease, and particularly of key diabetes indicators that can stratify risk for developing complications. Screening, such as annual eye exams and regular foot examination, is also instrumental in preventing or delaying the onset of complications.^2,3

People who develop the complications of diabetes incur far greater healthcare costs than those without complications. Compared to people without complications, hospital costs for those with microvascular complications were doubled, those with macrovascular complications were tripled and those with both micro- and macrovascular complications were 5.5 times as great.⁴

The UK Prospective Diabetes Study (UKPDS) showed that lowering mean HbA_1c by 1% was associated with a 14% decreased risk of heart attack, a 37% decreased risk of microvascular complications, and a 21% decrease in diabetes-related deaths.⁵ Lifestyle interventions, such as changes in diet and exercise, and medications can also modify the risk for development of complications.

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A stroke occurs when the blood supply to part of the brain is interrupted and brain tissue is damaged. The most common cause is a blocked blood vessel. Strokes can cause physical problems such as paralysis, problems with thinking or speaking, and emotional problems. People with diabetes are much more likely to have a stroke or heart disease. In fact, up to 80% of people with type 2 diabetes die from stroke or heart disease.¹

People with diabetes can reduce their risk of stroke by quitting smoking, controlling their blood pressure, improving their dietary intake, lowering their LDL-cholesterol, increasing their physical activity, and achieving or maintaining a healthy weight. In addition, aspirin should be considered in people with diabetes who are at increased risk for stroke but the risk for gastrointestinal bleeding or hemorrhagic stroke must be weighed against the potential benefit. People with atrial fibrillation may require conversion to normal sinus or chronic anticoagulation.²

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The hyperglycaemia associated with diabetes can damage nerves in the feet, which can eventually lead to a loss of feeling. This leaves feet vulnerable to injury or sores that may not be discovered immediately. If these injuries heal, there's no cause for concern. But diabetes can also damage the blood vessels, leading to poor circulation in the feet and hindering the body's ability to heal sores or other injuries. Left untreated, a minor foot injury could become a serious infection and even lead to tissue death, or gangrene. Severe damage might require toe, foot, or even leg amputation.

People with diabetes can reduce the risk of amputations by scheduling regular foot check-ups, where a health care professional inspects their feet for early signs of nerve damage, poor circulation, or other foot problems.⁸ Following a simple foot-care regime that includes daily washing, moisturising, and inspection for cuts or sores is also important.

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Coronary artery disease, the most common form of coronary heart disease, is caused by fatty deposits narrowing or blocking the blood vessels that supply the heart. A heart attack occurs when the blood supply to the heart is reduced or stopped completely.

People with diabetes are 2-4 times more likely to die from heart disease than people without diabetes.⁹

People with both type 1 and type 2 diabetes can reduce their cardiovascular risk through weight reduction, increased physical activity, blood pressure control, lipid lowering, tobacco cessation, and glycaemic control.⁶ Aspirin or antiplatelet therapy is recommended for primary prevention in people with type 2 diabetes who are at increased risk for cardiovascular disease.

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Hypoglycaemia is the term used to describe a state produced by a lower than normal level of blood glucose. Hypoglycaemia is generally an uncommon clinical event, however for many people with diabetes, it is a fact of life.¹ Low blood glucose levels may be precipitated by the dosage or timing of insulin or oral antidiabetic drug therapy, as well as delay in meal times, alcohol intake, or the presence of cor-morbid conditions such as renal insufficiency.² Thus, concerns about iatrogenic hypoglycaemia may be a barrier to the successful management of diabetes. Patients with established type 1 diabetes are at greater risk of hypoglycaemic episodes, as 10% of the time plasma glucose concentrations may be <2.8 mmol/l. These individuals can expect to suffer an average of two episodes of symptomatic hypoglycaemia per week and at least one incidence of severe hypoglycaemia each year. It is estimated that 2-4% of deaths in patients with type 1 diabetes are attributable to hypoglycaemia.¹

Hypoglycaemia is also an issue for patients with type 2 diabetes. The rate of severe hypoglycaemic episodes in patients with insulin-dependent type 2 diabetes is at least 10-fold lower than that in patients with type 1 diabetes.¹ Incidence is reduced further in type 2 patients who are treated with oral hypoglycaemic agents.^3,4

The symptoms associated with hypoglycaemia include sweating, fatigue, and feeling dizzy, but can include pale appearance, feeling weak and hungry, elevated heart rates, and blurred vision. In certain circumstances patients can become confused, lose consciousness, experience convulsions, and even lapse into a coma.¹

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Millions of tiny blood vessels (capillaries) with even tinier holes in them act as filters in the kidneys. As blood flows through these blood vessels, small molecules such as the waste products created by protein digestion are forced through the holes and enter the urine. Useful substances, such as protein and red blood cells, are too large to pass through the holes in the filter and stay in the blood. However, the high blood glucose levels associated with diabetes force the kidneys to filter too much blood. After many years of this overwork, they start to leak, causing useful protein to be lost in the urine. If kidney disease is only detected by the time larger amounts of protein are present in the urine, end-stage renal disease (ESRD) usually follows. A person with ESRD requires either a kidney transplant or dialysis, where the blood is filtered by machine. People with diabetes can reduce the risk of kidney disease by maintaining HbA_1c within their target range.

Historically, renal failure is the leading cause of death among people with type 1 diabetes.¹³ Diabetes is the number one cause of kidney failure and develops in 40 to 50% of all diabetics.^14,15

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Retinopathy is a complication of diabetes that can lead to blindness. It results from damage to the blood vessels in the back of the eye due to prolonged hyperglycaemia.

People with diabetes can reduce the risk of retinopathy through annual retinal screening, where the back of the eye is examined to detect any early signs of the complication. Laser therapy can detect and treat retinopathy and reduce the development of severe vision loss by an estimated 50-60%.^2,9

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