Diabetes mellitus is a group of diseases characterized by high levels of blood glucose resulting from defects in insulin secretion, insulin action or both (1). Diabetes is highly prevalent, afflicting approximately 150 million people worldwide (2), and this number is expected to rise to 300 million in the year 2025 (3).Much of this increase will occur in developing countries and will result from population ageing, unhealthy diet, obesity and a sedentary lifestyle (4). In developed countries, such as the United States, diabetes has been reported as the seventh leading cause of death (5), and the leading cause of lower extremity amputation, end-stage renal disease and blindness among persons aged 18 - 65 years (6 - 9). It has been estimated that diabetes costs the United States economy more than 98 billion dollars per year in direct and indirect costs (5,10). It has also been estimated that low-income families in the United States supporting an adult member with diabetes devote 10% of their income to his or her care, and that this figure rises to 25% in India (11).
There are four known subtypes of diabetes mellitus (1).
• Type 1 diabetes, previously called insulin-dependent diabetes mellitus (IDDM) or juvenile onset diabetes, accounts for 5 to 10% of all diagnosed cases of diabetes (12). Type 1 diabetes, caused by failure of pancreatic beta-cells to produce insulin, can afflict both children and adults who will require daily injections of insulin. Inadequate use of insulin results in ketoacidosis and this inevitable consequence limits the extent to which patients can ignore recommendations to take exogenous insulin and still survive. Ketoacidosis is a significant cause of mortality in young persons with type 1 diabetes (13,14). Patients with diabetic ketoacidosis often require hospitalization and, in most instances, poor adherence to insulin therapy is the suspected cause (15,16).
• Type 2 diabetes, previously called non-insulin-dependent diabetes mellitus (NIDDM) or adult-onset diabetes, may account for about 90% of all diagnosed cases of the disease. It is typically associated with being overweight and is caused by insulin resistance. For patients with type 2 diabetes, weight control, by means of dietary and physical activity regimens, is the cornerstone of the treatment. However, pancreatic beta-cell function decreases over time, so many patients will eventually require treatment with oral medications or exogenous insulin.
• Gestational diabetes develops in 2 to 5% of all pregnancies, but disappears postpartum (17). Risk factors include race/ethnicity and a family history of diabetes and obesity.
• Other specific types of diabetes result from specific genetic syndromes, surgery, drugs, malnutrition, infections and other illness, and account for 1 to 2% of all diagnosed cases of diabetes.