Diabetes mellitus results in considerable morbidity and mortality, affecting about 180 million people worldwide.
The disease is classified according to two distinct groups of patients:
Type I diabetes (previously known as “insulin dependent” or “insulin dependent”) is characterized by destruction of the insulin secretory pancreatic β-cells of the islets of Langerhans caused by an autoimmune process, usually leading to absolute insulin deficiency.
Type II diabetes (noninsulin dependent, adult-onset) is characterized by insulin resistance in peripheral tissues and an insulin secretory defect of the β-cell. Between 70 and 90% of diabetic patients have type II diabetes.
Current statistics suggest that an estimated 50% of diabetes sufferers remain undiagnosed.
The total number of people with diabetes is expected to rise to an estimated 300 million cases by the year 2025, with the most significant increases in developing countries, thought to be the result of population growth, aging, obesity, and sedentary lifestyles. Proportionally, the global population is 3predicted to increase by 64% between the years 1995 and 2025, compared with the prevalence of diabetes mellitus among adults, which is expected to rise by over 120%.
The development of diabetes immediately increases a patient's propensity for developing a broad spectrum of irreversible complications. Complications of diabetes can be largely divided into macrovascular and microvascular complications.
The macrovascular complications include cerebrovascular disease, coronary heart disease, and peripheral vascular disease.
The microvascular complications include diabetic retinopathy, diabetic neuropathy, and diabetic nephropathy.
The prevalence of these complications is strongly related to the prevalence, type, and duration of diabetes. Therefore, the increasing global population, changing age demographics, and predicted rise in the proportion of adults suffering from diabetes will inevitably be accompanied by an increase in the frequency of diabetic complications.
Diabetes has many manifestations in the eye, of which cataract and diabetic retinopathy are the most significant cause of visual impairment and blindness, and people with diabetes are 25 times more likely than the general population to become blind.
In developed countries, diabetic eye disease represents the leading cause of blindness in adults less than 75 years. Diabetic retinopathy is the most common complication in type I diabetes and nearly all patients will have some degree of retinopathy 15–20 years after diagnosis. More than 60% of type II diabetes sufferers will have evidence of diabetic retinopathy during this period.
Visual impairment as a result of diabetic retinopathy has a significant impact on patients' quality of life, and can compromise their ability to manage successfully their disease. This can in turn have a negative impact on the incidence of other diabetic complications and overall life-expectancy.