Diabetes is a disease that has been known since antiquity. In the seventh century, Chinese and Indian physicians observed the sugary taste of urine in some patients dying of a wasting, consumptive illness. This observation led to the hypothesis that diseased kidneys explained this mortal condition. In the nineteenth century, Langerhans described collections or islets of cells within the pancreas; these were later discovered to be important in the endocrine system.
A series of key observations also serve as the foundation for our current understanding of diabetes: Removing the pancreas from an animal will cause diabetes; the pancreas produces the hormone insulin in the islets of Langerhans; and administering insulin to someone with diabetes is effective treatment (Lefebvre, 2005). In 1923, the Nobel Prize in Medicine was awarded to Banting and Best for their isolation of insulin and administration of it to a 14-year-old boy dying from diabetes in Toronto General Hospital. We now know that diabetes mellitus can be the result of insulin deficiency, impaired insulin secretion, or resistance to the impact of insulin on target organs. This understanding was bolstered by advances in our ability to measure insulin levels in the middle of the twentieth century. Some patients with diabetes mellitus are deficient in measurable insulin, while others, despite adequate production of the hormone, either do not secrete it in a manner that preserves normal physiology or have organs resistant to its effects. Today we recognize that several pathogenic processes can cause diabetes and that there is an important interaction between the genetic makeup of an individual and environmental factors.
A MAJOR ILLNESS OF THE AGING POPULATION
Diabetes mellitus is a group of metabolic diseases characterized by high levels of blood glucose, or blood sugar, due to abnormalities in insulin secretion, insulin action, or both. It is one of the most common chronic diseases affecting older people; in the United States, one out of every ten healthcare dollars is spent for diabetes mellitus. Worldwide, it is estimated that 189 million people have the disease; in the United States, the estimate is 21 million, or 7 percent of the population. The average age of onset of the most common form of diabetes is 60 years of age, and the prevalence among people over age 65 years is 15-20 percent, with the higher rates among people over age 75. Because the disease may be asymptomatic for many years, it is estimated that one-third of older adults with diabetes mellitus are unaware of their condition. The prevalence of this disease varies with race and ethnicity. Non-Hispanic blacks and Hispanic whites are about 1.8 times as likely to develop diabetes as non-Hispanic whites. Alaska Natives and American Indians are 2.2 times as likely as non-Hispanic whites to have diabetes (Centers for Disease Control and Prevention, 2005).
Despite a sometimes prolonged asymptomatic period, diabetes mellitus is a serious condition associated with significant morbidity and shortened life expectancy. The type of diabetes commonly affecting older people is associated with a ten-year reduction in life expectancy and a mortality rate nearly twice that of people without this disease. Poorly controlled diabetes can be the cause of insidious decline in an older patient and is characterized by fatigue, weight loss, muscle weakness, and functional impairments. Longer-term complications of this disease include loss of vision, chronic kidney disease, atherosclerosis, and neuropathies. The rates of myocardial infarction, stroke, and kidney failure are increased approximately twofold, and the risk of blindness is increased approximately 40 percent in older persons with diabetes.
THE MANY FACES OF DIABETES
In 2006, the American Diabetes Association (20063) published the following diagnostic criteria. To establish the diagnosis of diabetes mellitus one or more of the following conditions must be met:
* Symptoms of polyuria (excessive urination), polydipsia (excessive thirst), and unexplained weight loss plus a casual plasma glucose concentration greater than 200 mg/dl. …