LEARNING OUTCOME AND OBJECTIVES:  Upon completion of this continuing education course, you will demonstrate increased knowledge of evidence-based guidelines for caring for persons with type 2 diabetes. Learning objectives to address potential knowledge gaps include:

• Review the underlying causes of diabetes.
• Describe the incidence, prevalence, costs, and groups at risk of developing type 2 diabetes.
• Discuss prevention strategies for persons at risk of developing type 2 diabetes.
• Describe the assessment and screening criteria used to diagnose and monitor patients.
• Review current recommendations for treating persons with type 2 diabetes.
• Describe the components of a long-term plan of care for persons with diabetes.
• Explain the necessary lifestyle modifications for these individuals.
• Discuss the most serious complications associated with type 2 diabetes and their effective treatment interventions.

WHAT IS DIABETES?

Diabetes mellitus—or, simply, diabetes—is a chronic illness in which the body is exposed to continual high levels of blood glucose, a condition known as hyperglycemia. In the short term, extreme hyperglycemia can lead to life-threatening dehydration and coma. Over the long term, hyperglycemia damages capillaries and larger blood vessels by thickening their walls and narrowing their inner diameters. This reduces the blood flow to many areas of the body and causes permanent tissue damage, notably to the retinas and the kidneys. Long-term high blood glucose levels also damage nerve endings.

• An estimated 34.2 million people, or 10.5% of the U.S. population, has diabetes.
• Around 7.3 million people have undiagnosed diabetes.
• Nearly half of American adults have diabetes or prediabetes.
• Diabetes kills more Americans annually than AIDS and breast cancer combined.
• People with diabetes have higher rates of death due to cardiovascular disease and higher rates of hospitalization for heart attacks and stroke.
• Diabetes is a leading cause of kidney failure, retinopathy, and nontraumatic lower limb amputations.
• An estimated 6 million Americans use insulin.
  (CDC, 2020; ADA, 2020a)

Almost all forms of diabetes stem from problems in the body’s production and use of insulin, the hormone that is responsible for keeping blood glucose levels in check. One cause of diabetes is the inability to produce enough insulin; for this problem, treatments include oral medications, non-insulin injectable medications, and insulin injections.

Another cause of diabetes is the inability of body tissues to respond sufficiently to normal amounts of insulin, or insulin resistance; here, the treatments include exercise, weight loss, and when needed, oral medications that increase tissue responsiveness to insulin.

Of the various forms of diabetes, the two most common are (ADA, 2020a):

• Type 1 diabetes, which is characterized by destruction of the insulin-secreting cells (beta cells) of the pancreas
• Type 2 diabetes, which is characterized by insulin resistance and progressively reduced secretion of insulin by beta cells

About 90% to 95% of people with diabetes have the type 2 form; 5% have type 1; and 1% to 5% have other rare types (CDC, 2020; ADA, 2020a). The typical patient with type 2 diabetes is an adult who has had the disease for many years before it worsens sufficiently to cause symptoms prompting healthcare intervention.

People who do not have especially high levels of blood glucose but who do have inefficient (“impaired”) mechanisms for handling blood glucose have a condition called prediabetes, which is diagnosed when fasting glucose levels are elevated in the range of 101–125 mg/dL on more than one occasion (CDC, 2020).

Currently, diabetes is incurable, and it takes daily management to prevent or delay further damage to the body. Consuming a healthy diet, participating in regular physical activity, maintaining a normal body weight, and avoiding tobacco use are ways to prevent or delay the onset of type 2 diabetes.

Diabetes can be treated and its consequences can also be avoided or delayed with regular screening for and treatment of complications (WHO, 2020). The most successful model for managing diabetes is a team approach. The patient is the daily healthcare manager, and a group of professionals—including physicians, nutritionists, nurses, and other allied health professionals—act as guides, advisors, monitors, and counselors.

History of Diabetes

Type 2 diabetes is one of the two main forms of diabetes mellitus, a disease that has been a problem during all of recorded human history. Diabetes is a Greek word that means “to pass through.” Diabetes was the name given to diseases in which a person continually drinks great quantities of fluid, which then pass through the body and are excreted as great quantities of urine. Diabetes is thus characterized by polydipsia (prodigious drinking) and polyuria (prodigious urinating).

Even in early times, two different diabetes diseases were distinguished: diabetes insipidus and diabetes mellitus. People with diabetes insipidus have symptoms of dilute, watery urine. This disease is now known to be caused most often by the insufficient secretion of ADH (antidiuretic hormone) by the pituitary gland. In contrast, people with diabetes mellitus produce urine that is denser than normal and that leaves crystals of sugar when the water in the urine is evaporated. Diabetes insipidus is rare, and even before the physiologic bases of the diseases were understood, when someone spoke simply of “diabetes,” they were usually referring to diabetes mellitus.

DIABETES IN THE PAST

Before the twentieth century, diabetes mellitus was usually fatal. Most often, diabetes occurred in people who were older than 50 years of age and obese. The disease came on gradually, with increasing thirst and correspondingly voluminous urination. The individual’s mouth and skin were always dry, and the breath often had a sweetish odor.

The disease progressed inexorably, bringing with it a host of problems. Eyesight failed from cataracts and nerve problems. Muscles weakened, skin infections and pneumonias were common, and people developed gangrene of the lower limbs. Diabetes led to digestive troubles, kidney disease, and heart failure. Death was usually from what was then called diabetic coma (now called diabetic ketoacidosis), which came on suddenly and was always fatal within a few days.

In the less-common cases in which children, teenagers, or young adults developed diabetes, the disease worsened much more rapidly. There were no good treatments for diabetes, although a low-carbohydrate diet slowed the progression of the disease in some individuals with obesity who developed the disease later in life.

THE DISCOVERY OF INSULIN

By the early 1800s, pancreatic damage was recognized in autopsies of people who died of diabetes, and late in that century German scientists showed that removing the pancreas from a dog would cause diabetes in the animal. However, diabetes could be prevented in these dogs if a piece of pancreas was sewn under the dog’s skin, and this suggested that the pancreas made a substance that prevented diabetes.

Attempts to extract this substance failed because the pancreas also makes a number of destructive enzymes, the presence of which in the extracts would destroy the key antidiabetes substance. In the early 1920s, the Canadian surgeon Frederick Banting and his assistant Charles Best, a medical student, devised a way to rid the pancreas of most of its destructive enzymes. From the remaining pancreatic tissue they extracted a hormone that would decrease the amount of sugar in the bloodstream and in the urine of diabetic dogs. They named this antidiabetes hormone insulin. Before the discovery and purification of insulin, diabetes was a fatal disease; after Banting and Best’s work, diabetes became a chronic illness (ADA, 2019).

Identifying the Two Types of Diabetes

At the beginning of the twentieth century, diabetes mellitus was considered one disease, although young people who developed the disease died much more quickly than people who first became ill in middle or old age. The new treatment with insulin, however, began to highlight a number of other differences. As early as the 1930s, clinicians found that people with diabetes could be divided into two classes according to the way they reacted to an injection of insulin.

People with insulin-sensitive diabetes (who tended to be young and prone to developing ketosis, a build-up of ketone bodies in body tissues and fluids, leading to nausea, vomiting, and stomach pain) easily disposed of an oral dose of glucose after receiving an injection of insulin. In contrast, people with insulin-insensitive diabetes (who were usually middle-aged and did not have ketotic episodes) did not significantly reduce their blood glucose levels after receiving the same amount of insulin.

TYPE 1 DIABETES

Today, insulin-sensitive diabetes is usually categorized as type 1 diabetes. In type 1 diabetes, the pancreas produces little or no insulin because the beta cells (the insulin-making endocrine cells in the islets of Langerhans of the pancreas) are not functioning. This is thought to be due to an autoimmune process that occurs in the beta cells. Type 1 diabetes occurs most commonly in young people, although it can occur in any age group (ADA, 2020b).

TYPE 2 DIABETES

Insulin-insensitive diabetes, on the other hand, is generally categorized as type 2 diabetes. Type 2 diabetes occurs most often in older adults, although it can occur at any age. Type 2 diabetes develops when the tissues in the body become resistant to insulin that is made by the pancreas or when the pancreas is unable to produce enough insulin. This is called insulin resistance (ADA, 2020b).

More than 90% of people with diabetes have the type 2 form, previously called insulin-insensitive diabetes, non-insulin-dependent diabetes, or adult-onset diabetes. In type 2 diabetes, the pancreas often produces enough insulin to prevent ketone (a chemical produced in the liver when fat is used for energy) formation but, because of insulin resistance, not enough to prevent hyperglycemia.

Although there is a hereditary (i.e., genetic) predisposition for the disease, type 2 diabetes does not appear to have a single cause. Aging, a sedentary lifestyle, or excess intra-abdominal fat can activate or enhance a person’s predisposition to develop type 2 diabetes (ADA, 2020b).

Type 2 diabetes worsens quickly if it is not treated. Both hyperglycemia and higher-than-normal circulating insulin levels (hyperinsulinemia) increase the existing insulin resistance. Hyperglycemia also injures the beta cells (the insulin-manufacturing cells) in the pancreas, and this makes it increasingly difficult for the pancreas to lower high levels of blood glucose. As these processes continue and interact with each other, the individual (or person with diabetes) has more frequent and higher episodes of hyperglycemia, which over time damage the eyes, kidneys, nerves, and blood vessels (ADA, 2020b).

Incidence and Prevalence of Type 2 Diabetes

Type 2 diabetes is now considered a worldwide epidemic. The U.S. Centers for Disease Control and Prevention estimates that over 34 million Americans have diabetes. The disease affects 10.5% of all Americans. Among people aged 18 years or older, 88 million (34.5% of the U.S. adult population) also have prediabetes. The National Diabetes Statistics Report for 2020 reveals higher rates of diabetes among several racial and ethnic minorities compared to the general population (CDC, 2020).

Worldwide, the number of people with diabetes has risen from 108 million in 1980 to 422 million in 2014 (WHO, 2020). Additional statistics published by the WHO offer an alarming picture of diabetes throughout the world. These data include:

• The global prevalence of diabetes among adults over 18 years of age has risen from 4.7% in 1980 to 8.5% in 2014.
• Diabetes prevalence has been rising more rapidly in middle- and low-income countries.
• Diabetes is a major cause of blindness, kidney failure, heart attacks, stroke, and lower limb amputation.
• In 2016, an estimated 1.6 million deaths were directly caused by diabetes and another 2.2 million deaths were attributable to high blood glucose.
• Almost half of all deaths attributable to high blood glucose occur before the age of 70 years. WHO projects that diabetes will be the seventh leading cause of death globally in 2030.

DIABETES BY AGE AND RACE

Diabetes is more common in older people. According to the CDC (2020), 11.5 million people aged 65 years or older have diabetes.

The rate of diabetes varies by race. In the United States, diabetes is more common among non-Whites than Whites. After adjusting for population age differences, 2017–2018 national survey data for people aged 18 years or older reveal the following prevalence rates for diagnosed diabetes:

• 14.7% of American Indians/Alaska Natives
• 11.7% of non-Hispanic Blacks
• 12.5% of Hispanics
• 9.2% of Asian Americans
• 7.5% of non-Hispanic Whites
  (CDC, 2020)

The CDC continues to gather data and update information regarding the incidence and prevalence of diabetes and prediabetes in the United States. Additional data from 2017–2018 include the following (the race groups include people of both Hispanic and non-Hispanic origin):

• 1.5 million new cases of diabetes were diagnosed.
• Compared to adults age 18 to 44 years, incidence rates of diagnosed diabetes were higher among adults age 45 to 64 years and in adults age 65 years and older.
• Non-Hispanic Blacks (8.2 per 1,000 persons) and people of Hispanic origin (9.7 per 1,000 persons) had a higher incidence compared to non-Hispanic Whites (5.0 per 1,000 persons).
  (CDC, 2020)

CHILDREN AND ADOLESCENTS

In the past two decades, type 2 diabetes has been reported among children and adolescents in the United States with an increasing frequency. The epidemic of obesity, the low level of physical activity among young people, and exposure to diabetes in utero may be contributing factors.

Children diagnosed with type 2 diabetes are usually between 10 and 19 years old, obese, and have a strong family history for type 2 diabetes. The prevalence of type 2 diabetes is increasing in children of all ethnic groups, however it has significantly increased in non-Hispanic Black children (CDC, 2020).

Obesity and sedentary lifestyle are key factors driving the dramatic increase of type 2 diabetes in our society. Type 2 diabetes is associated with increased associated comorbid conditions and early mortality (CDC, 2020).

The increase in prevalence of type 2 diabetes among children and adolescents is a new challenge for healthcare providers and the health system to monitor and manage. New strategies for prevention, early detection, and treatment must be developed and implemented as this new generation of people with type 2 diabetes matures. As these individuals enter the adult years, they may have unique health challenges and may be at risk for developing early complications because of the early onset of disease (CDC, 2020). This group may also have an increase in frequency of diabetes during the reproductive years, which may further increase diabetes in the next generation (ADA, 2020b).

Costs of Diabetes

The impact of diabetes is significant in monetary terms. Costs related to care and complications of the disease are dramatic and include the following factors:

• In 2017 the total economic burden in the United States of diagnosed diabetes was $327 billion, including $237 billion in direct costs and $90 billion in indirect costs (e.g. disability, early death, lost work time).
• People with diagnosed diabetes have healthcare costs over two times higher than what expenditures would be in the absence of diabetes.
• The cost of diabetes medications (notably insulin) is an ongoing barrier to treatment. Up to 25% of patients who are prescribed insulin report not using it because of cost barriers.
• Hospitalization rates for stroke were 1.5 times higher among adults with diabetes compared to those without diabetes.
• Diabetes is the leading cause of kidney failure, accounting for over 40% of all new cases of kidney failure.
• About 60% to 70% of people with diabetes have mild to severe forms of neuropathy.
• Hearing loss is about twice as common in adults with diabetes as those who do not have the disease.
• More than 60% of nontraumatic lower limb amputations occur in people with diabetes.
  (ADA, 2020c)