Diabetes mellitus (DM) is a chronic condition that results from the body's inability to sufficiently produce and/or properly use insulin. Insulin, a hormone secreted from beta cells in the pancreas, assists in the conversion of glucose into energy. Without insulin, the cells of the body, primarily in muscle, fat and liver tissue, cannot absorb sufficient glucose from the bloodstream. Consistent high levels of blood glucose can result in long-term damage, leading to the dysfunction and failure of various organs, such as the kidneys, eyes, nerves, heart and blood vessels. Complications in these organs can lead to death.
Diabetes mellitus is not a single disease, it occurs in several forms: type 1, type 2 and gestational diabetes. Type 1 and type 2 are the two most common forms of this chronic disease and represent about 10% and 90% respectively of the total diabetic population1.
Type 1 diabetes, previously known as insulin-dependent diabetes mellitus (IDDM), typically occurs in childhood or early adolescence, and treatment usually entails multiple daily injections of insulin for survival.
In type 1 diabetes, the immune system attacks the insulin-producing beta cells in the pancreas and destroys them. As a result, the pancreas then produces little or no insulin. Type 1 diabetes is not caused by obesity or by eating excessive sugar; rather, it is believed to be caused by a combination of genetic factors and environmental stressors. Scientists do not know exactly what causes the body's immune system to attack the beta cells, but they believe that both genetic factors and viruses are involved. Even when insulin is injected regularly, type 1 diabetes usually results in a drastic reduction in the quality of life and shortens the average life span by 15 years2,3.
Symptoms of type 1 diabetes include increased thirst, frequent urination, constant hunger, weight loss, blurred vision and extreme tiredness. If the condition is not diagnosed and treated in time with insulin, patients can lapse into a life-threatening coma. The characteristics of type 1 are as follows4:
Type 2 diabetes, previously known as non insulin-dependent diabetes mellitus (NIDDM), is the most common form of diabetes. It accounts for more than 90% of diagnosed diabetes. Type 2 diabetes typically occurs after the age of 40 years and is found in a higher proportion of individuals who are considered overweight. Individuals with type 2 diabetes are usually insulin resistant. By losing weight, exercising, or taking medications orally, most people with type 2 diabetes can overcome this resistance to insulin; however, some require daily insulin injections2.
Type 2 diabetes is now widely considered to be one component in a group of disorders called the metabolic syndrome, which includes insulin resistance, cholesterol and lipid disorders, obesity, high blood pressure, a high risk of blood clotting and disturbed blood flow to many organs1. Life expectancy is reduced by about 5 to 10 years among middle-aged adults with type 2 diabetes3.
The mechanisms of type 2 diabetes are not fully understood, but some experts suggest that it may involve the following three stages4: