Diabetes mellitus
Diabetes mellitus: Excerpt from Handbook of Diseases
A chronic disease of absolute or relative insulin deficiency or resistance, diabetes mellitus is characterized by disturbances in carbohydrate, protein, and fat metabolism.
This condition occurs in two forms: type 1, characterized by absolute insulin insufficiency, and type 2, characterized by insulin resistance with varying degrees of insulin secretory defects.
Onset of type 1 usually occurs before age 30 (although it may occur at any age); the patient is usually thin and requires exogenous insulin and dietary management to achieve control. Conversely, type 2 usually occurs in obese adults after age 40, although it’s commonly seen in North American youths. It’s most commonly treated with diet and exercise (in combination with antidiabetic drugs), although treatment may include insulin therapy.
Diabetes mellitus is estimated to affect nearly 8% of the population of the United States (16 million people), about one-third of whom are undiagnosed. Incidence is equal in men and women and rises with age.
Nearly two-thirds of people with diabetes will die of cardiovascular disease. It’s also the leading cause of renal failure and new adult blindness.
Causes
The effects of diabetes mellitus result from insulin deficiency. Insulin transports glucose into the cell for use as energy and storage as glycogen. It also stimulates protein synthesis and free fatty acid storage. Insulin deficiency or resistance compromises the body tissues’access to essential nutrients for fuel and storage.
Type 1A results from autoimmune beta-cell destruction, resulting in insulin deficiency. Type 1B leaves these immunologic markers but results in insulin deficiency and kerosis.
Other risk factors include the following:
❑ Obesity contributes to the resistance to endogenous insulin.
❑ Physiologic or emotional stress can cause prolonged elevation of stress hormone levels (cortisol, epinephrine, glucagon, and growth hormone). This raises blood glucose levels, which, in turn, places increased demands on the pancreas.
❑ Pregnancy causes weight gain and increases levels of estrogen and placental hormones, which antagonize insulin.
❑ Some medications can antagonize the effects of insulin, including thiazide diuretics, adrenal corticosteroids, and hormonal contraceptives.
Signs and symptoms
Diabetes may begin dramatically with ketoacidosis in type 1 or insidiously. Its most common symptom is fatigue, from energy deficiency and a catabolic state. However, many patients with type 2 diabetes may be asymptomatic.
Insulin deficiency or resistance causes hyperglycemia, which pulls fluid from body tissues, causing osmotic diuresis, polyuria, dehydration, polydipsia, dry mucous membranes, and poor skin turgor. In ketoacidosis and hyperglycemic hyperosmolar nonketotic state, dehydration may cause hypovolemia and shock. Wasting of glucose in the urine usually produces weight loss and hunger in uncontrolled type 1 diabetes, even if the patient eats voraciously.
Long-term effects
In diabetes, long-term effects may include retinopathy, nephropathy, atherosclerosis, and peripheral and autonomic neuropathy.
Peripheral neuropathy usually affects the hands and feet and may cause numbness or pain. Autonomic neuropathy may manifest itself in several ways, including gastroparesis (leading to delayed gastric emptying and a feeling of nausea and fullness after meals), nocturnal diarrhea, impotence, and postural hypotension.
Because hyperglycemia impairs the patient’s resistance to infection, diabetes may result in skin and urinary tract infections and vaginitis. Glucose content of the epidermis and urine encourages bacterial growth.
Diagnosis
In nonpregnant adults, diabetes mellitus is diagnosed with:
❑ at least two occasions of a fasting plasma glucose level greater than or equal to 126 mg/dl
❑ typical symptoms of uncontrolled diabetes and a random blood glucose level greater than or equal to 200 mg/dl
❑ a blood glucose level greater than or equal to 200 mg/dl at 2 hours after ingestion of 75 grams of oral dextrose.
Two tests are required for diagnosis; they can be the same two tests or any combination and may be separated by more than 24 hours.
An ophthalmologic examination may show diabetic retinopathy. Other diagnostic and monitoring tests include urinalysis for acetone and blood testing for glycosylated hemoglobin, which reflects glucose control over the past 2 to 3 months.
Treatment
Effective treatment for both types of diabetes normalizes blood glucose and decreases complications.
Type 1 diabetes
Treatment includes insulin replacement, diet, and exercise. Current forms of insulin replacement include single-dose, mixed-dose, split-mixed dose, and multiple-dose regimens. The multiple-dose regimens may use an insulin pump.
Human insulin may be rapid-acting (Regular), intermediate-acting (NPH or Lente), long-acting (Ultralente, Lantus), or a combination of rapid-acting and intermediate-acting (70/30, 75/25, or 50/50 of NPH and Regular).
Clinical tip Insulin Lispro or Novalogue may be used in place of Regular insulin. It’s rapid in onset (15 minutes) and makes waiting to eat after injection unnecessary. It has a short duration of action (4 hours), which decreases between-meal and nocturnal hypoglycemia.
Islet cell or pancreas transplantation is available and requires chronic immunosuppression.
Type 2 diabetes
Patients may require oral antidiabetic drugs to stimulate endogenous insulin production, increase insulin sensitivity at the cellular level, suppress hepatic gluconeogenesis, and delay GI absorption of carbohydrates.
UNDER STUDY: Studies have shown that treatment with a lipase inhibitor (such as orlistat) combined with a low-calorie diet significantly decreases the weight of overweight patients with type 2 diabetes. Patients following this therapy also displayed improvements in glycemic control and cardiovascular risk profile; levels of glycosylated hemoglobin, fasting glucose, and postprandial glucose improved significantly.
Both types
Treatment of both types of diabetes requires a diet planned to meet nutritional needs, to control blood glucose levels, and to reach and maintain appropriate body weight.
For the obese patient with type 2 diabetes, weight reduction is a goal. In type 1, the calorie allotment may be high, depending on growth stage and activity level. For success, the diet must be followed consistently and meals eaten at regular times.
UNDER STUDY: Vitamin E is under investigation for its cellular effects that can possibly reduce the risk of macrovascular disease in patients with type 2 diabetes mellitus. The antioxidant effects of vitamin E were supported, and it was found that, in high doses, vitamin E acts as an anti-inflammatory. It’s postulated that heart disease and stroke risk can be decreased because vitamin E reduces plaque formation at the endothelial level. Vitamin E may also have an effect on the metabolic syndrome that causes diabetes mellitus and may prevent the disease from occurring.
Complications
Treatment of long-term diabetic complications may include transplantation or dialysis for renal failure, photocoagulation for retinopathy, and vascular surgery for large-vessel disease. Meticulous blood glucose control is essential.
The Diabetes Control and Complications Trial has proved that intensive insulin therapy that focuses on keeping glucose at near-normal levels for 5 years or more reduces both the onset and progression of retinopathy (up to 63%), nephropathy (up to 54%), and neuropathy (up to 60%).
Special considerations
❑ Stress that compliance with the prescribed program is essential. Emphasize the effect of blood glucose control on long-term health. (See Controlling diabetes mellitus.)
❑ Watch for acute complications of diabetic therapy, especially hypoglycemia (vagueness, slow cerebration, dizziness, weakness, pallor, tachycardia, diaphoresis, seizures, and coma). Immediately give carbohydrates in the form of fruit juice, hard candy, or honey; if the patient is unconscious, subcutaneous, I.M. or I.V. glucagon or I.V. dextrose may be given.
❑ Be alert for signs and symptoms of ketoacidosis (acetone breath, dehydration, weak and rapid pulse, Kussmaul’s respirations) and hyperosmolar coma (polyuria, thirst, neurologic abnormalities, stupor). These hyperglycemic crises require I.V. fluids, insulin and, usually, potassium replacement.
❑ Monitor diabetic control by obtaining blood glucose levels.
❑ Watch for diabetic effects on the cardiovascular system, such as cerebrovascular, coronary artery, and peripheral vascular impairment, and on the peripheral and autonomic nervous systems.
❑ Treat all injuries, cuts, and blisters (particularly on the legs or feet) meticulously.
❑ Be alert for signs of urinary tract infection and renal disease.
❑ Urge regular ophthalmologic examinations to detect diabetic retinopathy.
❑ Assess for signs of diabetic neuropathy (numbness or pain in the hands and feet, footdrop, neurogenic bladder). Stress the need for personal safety precautions; explain that decreased sensation can mask injuries. Minimize complications by maintaining strict blood glucose control.
Clinical tip Screening should be done for diabetes mellitus on those with risk factors, including family history of the disease, obesity, ethnicity (Hispanics, Native Americans, Asian Americans, and Blacks are at higher risk), age 45 and older, history of impaired glucose tolerance or impaired fasting glucose, hypertension, hyperlipidemia, history of gestational diabetes mellitus, or women giving birth to a neonate weighing more than 9 lb (4 kg).
❑ Teach the patient to care for his feet by washing them daily, drying carefully between the toes, and inspecting for corns, calluses, redness, swelling, bruises, and breaks in the skin. Urge him to report any changes. Advise him to wear nonconstricting shoes and to avoid walking barefoot.
❑ Teach the patient how to manage his diabetes when he has a minor illness such as a cold, flu, or upset stomach.
❑ To delay the clinical onset of diabetes, teach persons at high risk to have good weight control, exercise regularly, increase the whole grains, fruits, and vegetables in their diet, and employ stress management techniques. Advise genetic counseling for young adult diabetics who are planning families.
❑ For further information, consult the Juvenile Diabetes Foundation, the American Diabetes Association, and the American Association of Diabetes Educators.
Pictures
Book Source Details
- Book Title: Handbook of Diseases
- Author(s): Springhouse
- Year of Publication: 2003
- Copyright Details: Handbook of Diseases, Copyright © 2003 Lippincott Williams & Wilkins.
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Copyright notice for book excerpts: Copyright © 2008 Lippincott Williams & Wilkins. All rights reserved.
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More About This Book:
Title: Handbook of Diseases
Authors: Springhouse
Publisher: Lippincott Williams & Wilkins
Copyright: 2003
ISBN: 1-58255-266-5
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