Diabetes is a chronic condition that occurs when the body cannot produce enough or effectively use insulin. Insulin is a hormone produced by the pancreas that allows glucose from food to enter the body's cells where it is converted into energy needed by muscles and tissues to function. As a result, a person with diabetes does not absorb glucose properly, and glucose stays circulating in the blood (hyperglycaemia) damaging tissues over time. This damage leads to life-threatening health complications.
People with diabetes have an increased risk of developing a number of serious health problems. Consistently, high blood glucose levels can lead to serious diseases affecting the heart and blood vessels, eyes, kidneys, and nerves. In addition, people with diabetes also have a higher risk of developing infections. In almost all high-income countries, diabetes is a leading cause of cardiovascular disease, blindness, kidney failure, and lower limb amputation. Maintaining blood glucose levels, blood pressure, and cholesterol close to normal can help delay or prevent diabetes complications. People with diabetes need regular monitoring for complications.
There are three main types of diabetes: type 1 diabetes, type 2 diabetes and diabetes during pregnancy (gestational diabetes mellitus). Type 1 diabetes is caused by an auto-immune reaction, where the body's defence system attacks the insulin-producing cells in the pancreas. The disease usually occurs in children or young adults. People with this form of diabetes need injections of insulin every day. Type 2 diabetes is the most common type of diabetes. It usually occurs in adults, but is increasingly seen in children and adolescents. In type 2 diabetes, the body is able to produce insulin but it is either not sufficient or the body is not responding to its effects, leading to a build-up of glucose in the blood. People with type 2 diabetes may remain unaware of their illness for a long time because symptoms may take years to appear or be recognised, during which time the body is being damaged by excess blood glucose. Many people are diagnosed only when complications of diabetes become evident.
There are several important risk factors for type 2 diabetes. These include: obesity, poor diet, physical inactivity and increasing age. The majority of people with type 2 diabetes do not usually require daily doses of insulin to survive. However, they may be prescribed insulin together with oral medication, a healthy diet and increased physical activity to manage their condition.
The number of people with type 2 diabetes is rising rapidly worldwide. This rise is associated with economic development, ageing populations, increasing urbanisation, dietary changes, and reduced physical activity. In high-income countries, type 2 diabetes tends to be more prevalent in the less well off. Diabetes is often more common in the wealthier parts of the population of low-income countries. However even in low-income countries, diabetes is already very common in the poorest sections of society-especially in urban areas, where one in six, or more, adults has diabetes. The underlying determinants of diabetes are the same the world over. Economic development is associated with increasingly 'obesogenic environments' characterized by decreased physical activity and increasing access to energy-rich diets.
People with high blood glucose levels, but not as high as those in people with diabetes, are said to have impaired glucose tolerance (IGT) or impaired fasting glucose (IFG). IGT is defined as high blood glucose levels after eating, whereas IFG is defined as high blood glucose after a fast. People with IGT (sometimes also the term pre-diabetes is used), have a higher risk of developing type 2 diabetes. IGT is associated with obesity and advancing age.
Diabetes is one of the most challenging health problems in the 21st century. It is one of the most common non-communicable diseases (NCDs) globally, affecting about 415 million people worldwide. It is the fourth or fifth leading cause of death in most high-income countries and there is substantial evidence that it is epidemic in many economically developing and newly industrialised countries.
(Reference: Adapted from: IDF Diabetes Atlas, 7th edition)