Diabetes Mellitus

Diabetes mellitus (DM) is a chronic disorder of carbohydrate, protein, and fat metabolism in which there is a discrepancy between the amount of insulin required by the body and the amount of insulin available. The Centers for Disease Control and Prevention (CDC) state that more than 120 million people in the United States are living with DM or prediabetes. Almost 10% of the U.S. population has DM. The 88 million people who have prediabetes will likely have DM within 5 years if they are not treated, and more than half of the people with that condition are unaware that they are prediabetic. The health-related problems of DM are extensive in lives lost and money spent. It is the seventh leading cause of death in the United States. DM is classified into several categories (Table 1).

Table 1 Types of Diabetes Mellitus

TYPE		DESCRIPTION
1		Patients are dependent on insulin for prevention of hyperglycemia or ketosis Formerly referred to as insulin-dependent DM Estimates are that 1.6 million people in the United States have type 1 DM The most serious life-threatening problem is diabetic ketoacidosis Time of onset is usually under age 20 years but may occur in adults 30–40 years Beta cells of pancreas have insulitis (pancreatic inflammatory response) with beta cell destruction
2		Patients are not dependent on insulin but ultimately may require insulin therapy to manage blood glucose control Patients have insulin resistance, impaired insulin secretion, and/or inappropriate glucagon secretion Formerly referred to as non-insulin-dependent DM Most common type of DM: Approximately 80%–90% of patients with DM have this type Most serious problem is the development of hyperosmolar hyperglycemic nonketotic syndrome Time of onset is usually over age 40 years Beta cells have no insulitis; resistance to insulin occurs at the target cell receptor
Gestational DM (GDM)		Patients develop glucose intolerance during pregnancy
Other types of diabetes		Diabetes develops secondary to other conditions, including pancreatic, hormonal, or endocrine disease and insulin resistance, or it is drug induced
Malnutrition-related DM		Occurs in underdeveloped countries to individuals with a history of malnutrition

The beta cells of the pancreas produce insulin and a protein called C-peptide, which are stored in the secretory granules of the beta cells and are released into the bloodstream as blood glucose levels increase. Insulin transports glucose and amino acids across the membranes of many body cells, particularly muscle and fat cells. It also increases the liver storage of glycogen, the chief carbohydrate storage material, and aids in the metabolism of triglycerides, nucleic acids, and proteins. In type 1 DM, beta cells of the pancreas have been infiltrated by lymphocytes and destroyed by autoimmune processes, whereas in type 2 DM, relative insulin deficiency occurs accompanied by resistance to the actions of insulin in muscle, fat, and liver cells. Insulin resistance is associated with increased levels of free fatty acids in the blood, reduced glucose transport in muscle cells, elevated hepatic glucose production, and increased breakdown of fat. For type 2 DM to occur, both insulin resistance and inadequate insulin secretion must occur.

Long-term complications, such as disease of the large and small blood vessels, lead to cardiovascular disease (coronary artery disease, peripheral vascular disease, hypertension), retinopathy, renal failure, and premature death. Diabetic patients also have nerve damage (neuropathy) that can affect vision and the peripheral nerves, resulting in numbness and pain of the hands or feet. The novel coronavirus 2019 disease (COVID-19) was linked to poorer outcomes for diabetic patients than for other patients. Experts suggest that the reasons for a worse prognosis is related to comorbidities such as hypertension and cardiovascular disease, obesity, and a proinflammatory state.

Because diabetic patients are hyperglycemic, they are at higher risk for infection because an elevated glucose encourages bacterial growth. The combination of peripheral neuropathies with numbness of the extremities, peripheral vascular disease leading to poor tissue perfusion, and the risk for infection makes the diabetic patient prone to feet and leg ulcers.

Causes ⬆ ⬇

The cause of DM is not known, but genetic, autoimmune, viral, environmental, and socioeconomic factors have all been implicated in the development of the disease. Type 1 DM is most likely an autoimmune response in patients with genetic susceptibility. Following an environmental stimulus, such as a virus or bacteria, antibodies attack the beta cells of the pancreas and cause insulitis—inflammation and destruction of the beta cells. When 80% to 90% of the beta cells are destroyed, the patient develops hyperglycemia. It is thought that type 2 DM is caused by hereditary insulin resistance or abnormal insulin production. It is generally considered to involve complex interactions between heredity and environmental factors. If insulin resistance is acquired rather than inherited, it is usually the result of obesity. Experts note that approximately 90% of individuals with type 2 DM are overweight or have obesity. Other factors related to the development of type 2 DM include age older than 45 years, weight greater than 120% of desirable body weight, family history of type 2 diabetes, environmental pollutants, low birth weight, and an energy-dense diet.

Genetic Considerations ⬆ ⬇

DM is a complex disorder, with several genes and the environment working together. Type 1 DM is an autoimmune disease with approximately 30% to 50% twin concordance rate in monozygotic twins. Variants in the HLA allele (DR3, DR4) account for more than 50% of cases, but recent studies have found over 40 chromosomal regions that confer risk for type 1 diabetes. Type 2 DM is a heterogeneous disease with both a genetic and an environmental component (heritability estimates vary from 20% to 80%). Individuals with one affected parent have a 40% chance of developing type 2 DM, while those with two affected parents have a 70% chance. There is also varied genetic linkage in different populations (e.g., loci on chromosomes 2 and 11 are linked in Mexican Americans, whereas different loci on chromosomes 12 and 7 are implicated in Finns and Pima Indians, respectively). There are now over 100 loci associated with type 2 DM risk. The strongest and most consistent risk gene is TCF7L2, which encodes a signaling protein active in beta cells. Single-gene disorders of the beta cell can also cause familial DM. Maturity-onset diabetes of the young (MODY) is associated with autosomal dominant inheritance. MODY has the following characteristics: onset in at least one family member younger than 25 years old, the absence of autoantibodies and ketosis, and correction of fasting hyperglycemia without insulin for at least 2 years.

Sex and Life Span Considerations ⬆ ⬇

Approximately 1.6 million people have type 1 DM in the United States, where it is more common in males than females. Type 1 most commonly develops in childhood or before age 20 years but can occur at any age. Onset is often very abrupt. Because of the early age of onset, teenagers often deal with the long-term complications of the disease.

Type 2 DM usually occurs after age 40 years, particularly in individuals who are overweight or have hereditary factors, and occurs in males and females approximately equally. Type 2 DM is becoming increasingly common in all groups because DM prevalence increases with age and people are living longer than in past centuries. In addition, it is more frequent in younger people in accordance with the rising prevalence of childhood obesity. GDM, which is present during pregnancy, occurs in 3% to 10% of pregnant women, usually in those older than age 30 years.

Health Disparities and Sexual/Gender Minority Health ⬆ ⬇

The prevalence of type 2 DM in the United States varies by race and ethnicity. The American Diabetes Association reports the prevalence is 14.8% in Native American persons, 12.5% in Hispanic persons, 11.7% in Black persons, 7.4 in White persons, and 5.6% to 12.6% (depending on ancestry) in Asian persons. Asian persons are at risk for type 2 DM at lower weights than other persons. Non-Hispanic Black and Hispanic persons bear a disproportionate burden of type 2 DM when compared to non-Hispanic White persons. They also have higher rates of retinopathy, end-stage renal disease, and limb amputation than White persons. Experts suggest that these disparities occur for biological (genetic predisposition and fat distribution) as well as social factors such as income, language and literacy barriers, and limited access to and discrimination during healthcare. Several other factors lead to health disparities in persons with diabetes. Those with private insurance have been found to have better control of conditions such as blood pressure and visual disturbances related to DM as compared to persons who are uninsured, possibly because of improved diabetes management. Persons living in rural America have a higher prevalence of obesity and type 2 diabetes than urban populations and less access to behavioral programs to manage risks. Disparities in developing GDM also exist for foreign-born pregnant people. The relative risk for foreign-born versus U.S.-born pregnant people is higher across most ethnic groups.

Transgender is a term used to describe persons whose gender identity is different from their sex assigned at birth. Approximately 1% of the U.S. population identify themselves as transgender. Sexual and gender minority persons have higher odds for multiple chronic conditions, cancer, and poor quality of life, and are more apt to have disabilities than cisgender males and females (cisgender is a term used to describe persons whose gender identity and gender expression are aligned with their assigned sex listed on their birth certificate). Gender-affirming hormone therapy is the use of hormone therapy for gender transition or gender affirmation and can be masculinizing or feminizing. It may also affect cardiovascular health in transgender females. In a large sample, researchers have found that transgender men and women are more likely to be overweight than cisgender women. Compared to cisgender women, transgender women reported higher rates of diabetes, ischemic stroke, angina/coronary disease, and myocardial infarction. Gender-nonconforming persons reported higher odds of myocardial infarction than cisgender women. Transgender women also had higher rates of any cardiovascular disease than cisgender men (Cacerese, Jackman, et al., 2020; Connelly et al., 2019). Transgender persons are more prone to DM as they age than other groups (Gooren & T'Sjoen, 2018).

Global Health Considerations ⬆ ⬇

DM is a global epidemic, with the number of people with DM exceeding 422 million. The International Diabetes Federation states that by 2045, the number will exceed 700 million, and the countries with the most cases include the most populous countries of the world as well as Western Europe. Some experts note that type 1 DM is increasing by up to 5% each year in the Middle East, Western Europe, and Australia. Scandinavian countries have the highest prevalence rates for type 1 DM, while China and Japan have the lowest prevalence.

Type 2 DM is more common in developed countries than in developing countries. Experts suggest that in developing countries, and particularly in Africa, people ingest fewer calories and have higher levels of activity (less sedentary) than in North America and Western Europe. As countries become more developed, however, the prevalence of weight gain and type 2 DM increases dramatically. Africa will likely be the location for the largest increase in people with type 2 DM in the next decade. Screening for GDM occurs less often in developing countries than developed countries, decreasing the opportunity for early management.

Assessment ⬆ ⬇

ASSESSMENT

History

The timing of symptom appearance is important in DM. Type 1 DM often occurs suddenly, and patients may report symptoms of only days in duration. Establish a history of the patient's usual weight gains and losses; weight loss is common in type 1 DM. Determine if the patient has been under stress, had an infection, feels fatigued, had muscle cramping, or had nausea or blurred vision. Ask if the patient has experienced excessive thirst (polydipsia), excessive urination (polyuria), or excessive hunger (polyphagia). The most common symptom of DM is fatigue; determine if the patient has experienced fatigue out of the ordinary. Ask females of childbearing age if they are pregnant. Establish a history of using medications that antagonize the effects of insulin.

Patients with type 2 DM may not report these symptoms. However, ask whether the patient has experienced any recent itching or blurred vision or frequent infections, which are common complaints with type 2 DM. Question if the patient has experienced any visual difficulties, kidney problems, or changes in circulation and sensation to the extremities, such as numbness or tingling (paresthesia) or pruritus.

Physical Examination

The most common symptoms are polydipsia, polyuria, and polyphagia. Appearance may be entirely normal, or the patient with type 1 DM may have weight loss, muscle wasting, muscle cramping, and loss of subcutaneous fat. They may experience nausea, abdominal pain, and changes in bowel patterns. The patient with type 2 DM, by contrast, may have thin limbs with fatty deposits around the face, neck, and abdomen. Observe the color of the skin and note any changes in sensation of temperature, touch, and pain. Examine both feet closely, including the spaces between the toes, for signs of skin ulcers or infection. Assess the legs and feet to identify any unhealed wounds or ulcers. Check the temperature of the skin, which often feels cool, and the skin turgor, which is often poor.

When assessing vital signs, you may note hypertension, a common complication in diabetic patients. Palpate the peripheral pulses to determine their strength, regularity, and symmetry. During the neurological examination, use an ophthalmoscope to evaluate the patient for retinopathy or cataracts. Assess the patient for any signs and symptoms of hypoglycemia or hyperglycemia (Table 2).

Table 2 Signs, Symptoms, and Treatment of Hypoglycemia and Hyperglycemia

HYPOGLYCEMIA
Cause: Usually secondary to excess insulin, exercise, or not enough food		Signs and Symptoms Nervousness Diaphoresis (heavy sweating) Weakness Fatigue Palpitations Tremors or shaking Blurred or double vision Headache Confusion
Irritability Hunger Tachycardia Hypotension Tachypnea Pallor Incoherent speech Numbness of tongue and lips Coma		Treatment Provide rapidly absorbed source of glucose: Fruit juice Graham crackers Sugar cubes, sugar packets Hard candy As symptoms improve: Provide a meal or source of complex protein or carbohydrates Provide emotional support
		HYPERGLYCEMIA
		Cause: Usually secondary to insufficient insulin, illness, or excess food
Signs and Symptoms Nausea Vomiting Anorexia Abdominal cramping Thirst Lethargy Kussmaul breathing Increased temperature Flushed or dry skin Poor skin turgor Dry mucous membranes		Confusion Irritability Fatigue Weakness Numbness Tachycardia Hypotension Decreased level of consciousness Coma Fruity breath
Treatment (requires hospitalization) Restore fluid balance Replace electrolytes Lower blood glucose with regular insulin Monitor level of consciousness, vital signs, intake and output, and electrolytes Provide emotional support

Psychosocial

Management of DM is a lifelong endeavor with multiple consequences related to mental and physical health. The need for daily management with medications, diet, and exercise repeatedly reminds the individual of the illness. In addition, the reality of a long-term illness may affect individuals' view of themselves, resulting in lower self-esteem. Young people with type 1 DM may have trouble managing developmental tasks and a chronic disease simultaneously. Parents may become overprotective, and children may have delayed emotional maturation.

Diagnostic Highlights

Test	Normal Result	Abnormality With Condition	Explanation
Fasting (no food for at least 8 hr before measurement) plasma glucose (FPG)	70–100 mg/dL	>126 mg/dL	Insufficient insulin is available to transport insulin into body cells
Glucose tolerance test (2 hr after oral ingestion of 75 g of glucose; glucose is given after an overnight fast)	<140 mg/dL	>200 mg/dL; levels from 140 to 200 mg/dL indicate impaired glucose tolerance	Insufficient insulin is available to transport insulin into body cells
Hemoglobin A_1c	4%–6%	>8% poorly controlled diabetics; < 7% well-controlled diabetics; initial diagnosis is made when level reaches 6.5%	Integrated measure of blood glucose profile over the preceding 2–3 mo; A_1c is formed when glucose in the blood binds irreversibly to hemoglobin; since normal life span of red blood cells is 90–120 days, A_1c is eliminated only when the red cells are replaced

Other Tests: Urinalysis (glycosuria). Note: The diagnosis of DM is made when FPG is greater than or equal to 126 mg/dL on two occasions or random glucose is greater than or equal to 200 mg/dL along with the classic symptoms of DM (polyuria, polydipsia, polyphagia, weight loss). The goal of treatment is to lower and maintain blood glucose levels into the following range: preprandial blood glucose levels of 90 to 130 mg/dL and HbA_1c levels of less than 7%.

Primary Nursing Diagnosis ⬆ ⬇

Diagnosis

DiagnosisImbalanced nutrition: less than body requirements related to decreased oral intake, nausea, vomiting, and/or insulin deficiency as evidenced by weight loss

Outcomes

OutcomesNutritional status: Food and fluid intake; Nutritional status; Biochemical measures; Fluid balance; Knowledge: Diabetes management; Medication response

Interventions

InterventionsNutrition management; Nutrition therapy; Nutritional counseling and monitoring; Fluid/electrolyte management; Medication management

Planning and Implementation ⬆ ⬇

PLANNING AND IMPLEMENTATION

Collaborative

There is no known cure for DM, although pancreatic transplantation is available in some medical centers and is usually accomplished when patients also require a kidney transplant for end-stage renal disease. Continuous glucose monitoring (CGM) checks glucose levels regularly, and standard blood glucose meters use a drop of blood to check glucose levels. Management of the disease focuses on lifelong control of the serum glucose level to prevent or delay the development of complications. Individuals with type 1 DM require subcutaneous insulin administration. Insulin may be rapid, intermediate, or slow acting and may be delivered by multiple daily injections, or continuous subcutaneous insulin infusion with a battery pump. Technology is rapidly changing to better serve patients' needs for glucose monitoring and insulin pumps. The diabetes team assists patients to select the best systems for themselves. Ideally, blood glucose should be maintained at near normal levels and hemoglobin A_1c at levels under 7%. Patients learn to self-monitor to adjust their insulin dose as indicated. They also need to test for urine ketones when they have high or fluctuating levels of blood glucose or develop symptoms of a cold or other illnesses.

Patients with mild DM and those with type 2 DM or GDM may be able to control the disease by diet management alone. A diabetic diet attempts to distribute nutrition and calories throughout the 24-hour period. Daily calories consist of approximately 50% carbohydrates and 30% fat, with the remaining calories consisting of protein. The total calories allowed for an individual within the 24-hour period are based on age, weight, activity level, and medications.

In addition to strict dietary adherence to control blood glucose, obese patients with type 2 DM also need weight reduction. The dietitian selects an appropriate calorie allotment depending on the patient's age, body size, and activity level. A useful adjunct to the management of DM is exercise. Physical activity increases the cellular sensitivity to insulin, improves tolerance to glucose, and encourages weight loss. Exercise also increases patients' sense of well-being concerning their health.

Pharmacologic Highlights

Medication or Drug Class	Dosage	Description	Rationale
Insulin	Varies with severity to maintain premeal blood glucose of 80–130 mg/dL and HbA_1c< 7%	Hormone; hypoglycemic	Hormonal supplement to replace deficient or absent levels of insulin; can be rapid acting (genetically engineered preparations: lispro, glulisine, and aspart), short acting (regular insulin: zinc insulin crystals in solution), intermediate acting (NPH [neutral protamine Hagedorn]: crystalline suspension of human insulin with protamine and zinc), long acting (glargine, insulin detemir)
Antidiabetics	Varies with drug	Several groups of medications besides insulin are available in the treatment of DM: sulfonylureas, alpha-glucosidase inhibitors, biguanides, meglitinide derivatives, thiazolidinediones	Varies by drug; sulfonylureas stimulate release of insulin from beta cells of pancreas; alpha-glucosidase inhibitors slow carbohydrate breakdown in small intestine; biguanides decrease hepatic glucose output, enhance peripheral glucose uptake; meglitinide derivatives are short-acting insulin secretagogues; thiazolidinediones are insulin sensitizers
Exenatide (Byetta)	5 mcg SC bid within 1 hr before meals in the morning and evening	Incretin mimetic agent	Mimics glucose-dependent insulin secretion, suppresses elevated glucagon secretion, delays gastric emptying; used to improve glycemic control for type 2 diabetics

Other Drugs: Insulin pumps for type 1 DM: Continuous subcutaneous insulin infusion by battery-operated pump allows for a continuous subcutaneous infusion of rapid-acting insulin. The pump provides a programmed dose of insulin that also can be administered as a bolus dose before a meal. The patient self-monitors glucose levels and adjusts the bolus dose. The pump method provides better glucose control than multiple injections. Other therapies for type 2 DM: dipeptidyl peptidase IV inhibitors, glucagonlike peptide. Rapid-acting insulin aspart (Fiasp) is a human insulin analog formulated with niacin to speed absorption and can be used to treat adults.

Independent

If the patient has recently been diagnosed with DM, explain the disease process, the goals of management, and strategies to limit complications. Use simple explanations for clarity, answer questions, and provide written information for the patient to refer to between teaching sessions. In addition to general information on the disease process and reinforcement of collaborative teaching about medications and nutrition, the patient needs specific information about foot and vision care.

Explain that all cuts and blisters need to be cleaned and treated with an antiseptic preparation. If a cut or blister begins to appear infected (warmth, pain, swelling) or has drainage, encourage the patient to notify the primary healthcare provider immediately. Teach the patient to avoid constricting clothing such as constricting stockings, garters, girdles, or elastic slippers. If the patient needs to be on bedrest, encourage the patient to keep bed linens loose over the feet and legs. Instruct the patient to avoid very hot baths if peripheral neuropathy causes decreased temperature sensation.

If the patient is a child or teenager, recognize that a diagnosis of DM changes a family permanently. Parents usually expect their child to be healthy and often react with shock and disbelief. The impact on the child depends on the child's age. School-age children may be impressed with the new “condition” and may be challenged by the new skills it involves. Adolescents, in comparison, may feel unfairly victimized and respond by becoming depressed, resistant, uncooperative, or insecure. Work with the entire family to support their adaptation to the illness. Introduce the family to other families with the same problem. If the problems are abnormal, make a referral to a counselor.

Evidence-Based Practice and Health Policy

Rosenstock, J., Bajaj, H., Janež, A., Silver, R., Begtrup, K., Hansen, M., Jia, T., & Goldenberg, R. (2020). Once-weekly insulin for type 2 diabetes without previous insulin treatment. New England Journal of Medicine, 383, 2107–2116.

The authors explored whether reducing the frequency of basal insulin injections by using insulin icodec (a basal insulin analogue designed for once-weekly administration) would encourage treatment acceptance and adherence among patients with type 2 diabetes. The authors conducted a 26-week, randomized trial to investigate the efficacy and safety of once-weekly insulin icodec as compared with once-daily insulin glargine U100 in patients who had not previously received long-term insulin treatment. Patients whose type 2 diabetes was inadequately controlled (glycated hemoglobin level, 7.0%–9.5%) were selected. The primary endpoint was the change in glycated hemoglobin level from baseline to 26 weeks. The authors enrolled 247 patients.
A total of 247 participants were randomly assigned to two groups with similar characteristics, one of which received icodec and the other received glargine insulin. There were no differences in the groups in the change from baseline in glycated hemoglobin level and at 26 weeks. There were no differences in adverse events between the groups. The authors concluded that once-weekly treatment with insulin icodec had glucose-lowering efficacy and a safety profile similar to once-a-day glargine insulin.

Documentation Guidelines ⬆ ⬇

Results of urine and blood tests for glucose
Physical findings: Visual problems, skin problems or lesions, changes in sensation or circulation to the extremities
Patient teaching, return demonstrations, patient's understanding of teaching
Response to insulin

Discharge and Home Healthcare Guidelines ⬆

Medications

Patients need to understand the purpose, dosage, route, and possible side effects of all prescribed medications. If the patient is to self-administer insulin, have the patient demonstrate the appropriate preparation and administration techniques.

Prevention

The patient and family require instruction in the following areas to minimize or prevent complications of DM.

Diet.

Explain how to calculate the American Diabetic Association exchange list to develop a satisfactory diet within the prescribed calories. Emphasize the importance of adjusting diet during illness, growth periods, stress, and pregnancy. Encourage patients to avoid alcohol and refined sugars and to distribute nutrients to maintain a balanced blood sugar throughout the 24-hour period.

Insulin.

Patients need to understand the type of insulin prescribed. Instructions should include onset, peak, and duration of action. Stress proper timing of meals and planning snacks for the time when insulin is at its peak and recommend an evening snack for those on long-acting insulins. Reinforce that patients cannot miss a dosage, and there may be a need for increasing dosages during times of stress or illness. Teaching regarding the proper preparation of insulin, how to administer, and the importance of rotating sites is necessary.

Urine and Blood Testing.

Teach patients the appropriate technique for testing blood and urine and how to interpret the results. Patients need to know when to notify the physician and increase testing during times of illness.

Skin Care.

Stress the importance of close attention to even minor skin injuries. Emphasize foot care, including the importance of properly fitting shoes with clean, nonconstricting socks; daily washing and thorough drying of the feet; and inspection of the toes, with special attention paid to the areas between the toes. Encourage the patient to contact a podiatrist as needed. Because of sensory loss in the lower extremities, teach the patient to test the bath water to prevent skin trauma from water that is too hot and to avoid using heating pads.

Circulation.

Because of the atherosclerotic changes that occur with DM, encourage patients to stop smoking. In addition, teach patients to avoid crossing their legs when sitting and to begin a regular exercise program.

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DRG Information ⬇

Introduction ⬆ ⬇