Hyperglycemia is a complex metabolic condition characterized by abnormally high levels of blood sugar (blood glucose) in circulating blood, usually as a result of diabetes mellitus (types 1 and 2), although it can sometimes occur in cystic fibrosis and near-drowning (submersion injury).
Description
Hyperglycemia, also known as diabetic ketoacidosis, is a condition that develops over a period of a few days as the blood glucose levels of a type 1 or type 2 diabetic gradually rise. Ketoacidosis occurs when increasing glucose levels are met by a lack of sufficient or effective insulin production, starting a sequence of physiologic events as follows:
The combination of excess glucose production and low glucose utilization in the body raises levels of blood glucose, which leads to increased urinary output (diuresis) followed quickly by a loss of fluid and essential mineral salts (electrolytes) and, ultimately, dehydration. The loss of fluid may finally result in dehydration. If the entire process is severe enough over several hours (serum glucose levels over 800mg/dL), swelling can occur in the brain (cerebral edema), and coma can eventually result.
In a metabolic shift to a catabolic (breaking down) process, cells throughout the body empty their electrolytes (sodium, potassium, and phosphate) into the bloodstream. Electrolytes control the fluid balance of the body and are important in muscle contraction, energy generation, and almost all major biochemical reactions in the body. As a result of electrolyte imbalance, many functions can become impaired.
Free fatty acids from lipid stores are increased, encouraging the production of ketoacids in the liver, leading to an over-acidic condition (metabolic acidosis) that causes even more disruption in body processes.
Without effective treatment of the hyperglycemic episode, the child can lapse into a diabetic coma, which sometimes leads to death.
In diabetes type 2, which is characterized by insulin resistance, enhanced glucose production in the liver and decreased insulin secretion can be aggravated by low physical activity and/or a high-calorie, high-fat diet. Over time as glucose production accelerates, the child develops hyperglycemia or glucotoxicity and lipotoxicity (hyperlipidemia or high fat levels in the blood) as well. It is primarily thought to be a disease affecting sedentary, obese adults over age 40, but it is found in young people as well, most of them obese at the time of diagnosis. Pediatrictype 2 diabetes is increasing in the early 2000s among adolescents and has become the fastest growing form of diabetes. Therefore, hyperglycemic episodes are also noted to be increasing in frequency among young people admitted to hospitals for treatment of diabetes.
Demographics
The incidence of hyperglycemia approximately parallels the incidence of diabetes type 1 cases, which represents about 70 percent of all diabetes cases (17 million Americans diagnosed) in the United States. It occurs more in whites than blacks or Asians. About 30 percent of all new cases of diabetes are children with diabetes type 2. Diabetes type 2 occurs more often in African American youth but also in Native Americans, white Americans, and Hispanic youth between ages 10 and 19. Those with type 2 have fewer symptoms and are not treated as frequently for hyperglycemia.
Causes and symptoms
Diabetes is a chronic metabolic disorder with hyperglycemia, gradually rising levels of glucose, as its primary characteristic. As diabetes develops and symptoms increase, hyperglycemia becomes progressive but will occur only occasionally in the carefully managed
diabetic patient. Hyperglycemia can be triggered by irregular self-administration of insulin, by insulin resistance or defective insulin response in the body, by stress or infection, and by the activation of certain autoimmune processes characteristic of type 1 diabetes. It occurs in 20 to 40 percent of children newly diagnosed with diabetes and in children who are not yet successfully managed. Many young type 2 diabetics do not have symptoms because their hyperglycemia is moderate compared to type 1 diabetics, and they are not taking insulin.
The first signs of hyperglycemia or ketoacidosis are frequent urination and increased thirst. The child may then show any of the following symptoms:
The pediatrician or family doctor should be consulted about any sudden change in the child's urinary output, frequency of urination, or increased thirst, especially if accompanied by dry skin or mouth, flushed face, headache, abdominal pain, nausea or vomiting, unusual drowsiness and lack of movement, rapid heartbeat, or difficulty breathing. Parents should be aware of the last insulin injection if the child is on insulin therapy.
Diagnosis
Hyperglycemia can be diagnosed fairly quickly in known diabetic children. The non-fasting serum glucose will exceed 200mg/dL with classic symptoms such as increased urination, extreme thirst, dry skin or mouth, flushed face, headache, abdominal pain, nausea or vomiting, unusual drowsiness and lack of movement, rapid heartbeat, or difficulty breathing. If elevated glucose levels are present, the doctor will want to determine if ketoacidosis is also present by measuring levels of ketones in the blood serum and urine. Electrolyte levels will be measured along with carbon dioxide and pH and serum osmolality, which may indicate hypertonic dehydration. Routine screening of blood glucose levels and glucose tolerance tests is not recommended in children; symptoms are believed to help confirm hyperglycemia more readily. It is also not considered necessary to test non-obese children for autoimmune antibodies, which are more apt to be found in adult type 2 diabetics.
Treatment
Treatment for hyperglycemia must be delivered carefully and with close monitoring to avoid the risk of hypokalemia (higher than normal serum levels of potassium) and subsequent cerebral edema. Treatment will take place over a period of several days, including administration of insulin, usually in combination with administration of intravenous fluids and salts to restore fluid and electrolyte balance. Fluid intake and output is carefully monitored, and serum electrolytes are tested hourly or even more frequently to make sure balance is restored to support normal metabolic activity in the body. Children must be rehydrated very gradually; this can be done orally in mild hyperglycemia and over an extended period (30 to 36 hours) of intravenous administration with severe hyperglycemia. Administration of insulin helps move glucose back into cells, reduces glucose production by the liver, and stops the release of fatty acids. Insulin injections, while helping to normalize glucose production, also increase the risk of hypokalemia and abnormally low levels of glucose in the blood (hypoglycemia), the opposite of the hyperglycemic condition being corrected. Glucose is sometimes infused with the insulin to help avoid hypoglycemia. The insulin infusion will be slowed once hyperglycemia has been corrected (blood glucose levels less than 250mg/dL); in children with moderate hyperglycemia, this can often be accomplished within 24 hours. It may take several days, however, to restore normal cellular levels of potassium, sodium, and phosphate. The acidosis will be reversed, reflected in a gradual increase in pH.
In severe cases of hyperglycemia in which cerebral edema occurs, mannitol is administered at the first sign of edema, such as unconsciousness, difficulty breathing, severe headache, irregular heartbeat, or seizures. Changes can occur very rapidly. Children with moderate to severe hyperglycemia may be treated in an intensive care unit for continuous monitoring and rapid response capabilities.
In rare instances, a child may have a hyperglycemic episode that is triggered by a stressful situation or a physically challenging situation such as another illness. Transient hyperglycemia can be triggered by any type of stress that overtaxes the child's mental and physical resources. Stress hyperglycemia may be reversed completely
when the stressors are removed or relieved. Temporary hyperglycemia of this type will still require careful monitoring for symptoms and testing and treatment as above if any symptoms occur.
Nutrition, of course, is important in the treatment of diabetes and accordingly can play a role in preventing hyperglycemic episodes. Diabetic children must avoid sweetened and high-carbohydrate foods such as white flour and white sugar products and generally eat a high-fiber, low-fat diet consisting of whole grains, high quality protein (lean meat, eggs, low-fat dairy), fresh vegetables, and fresh fruits.
Prognosis
The prognosis for children with mild to moderate hyperglycemia is good; the condition can usually be corrected within 24 hours. Severe hyperglycemia (serum glucose levels in the range of 800mg/dL) may lead to cerebral edema, coma, and death if not treated immediately. Hyperglycemia in children during severe illness is a risk factor for poor outcomes in the underlying illness and has been reported as a cause of increased mortality in pediatric intensive care units. Morbidity (the incidence of other diseases) and mortality are higher in adults than in children because of long-term complications that include vascular conditions, circulatory problems, nervous system disorders, liver problems, and heart disease.
Prevention
Occurrences of hyperglycemia can be prevented by careful monitoring of blood glucose levels and insulin injections while balancing exercise and diet. Diabetic adolescents are especially susceptible to hyperglycemia, since hormone levels are in flux and many adolescents exhibit erratic eating and sleeping patterns. Athletic activities can be beneficial, since exercise makes use of surplus blood glucose. Obese children must be encouraged to eat properly and to avoid the fats and sugary sweets that can lead to increased weight, decreased mobility, and hyperglycemia.
Parental concerns
Parents of a diabetic child may live with the uncertainty of possible hyperglycemic episodes but can be reassured by knowing that continuous glucose monitoring, a proper diet as advised by the pediatrician, insulin therapy if prescribed, and appropriate exercise can control the disease and help avoid extremes that lead to hyperglycemia. It is important to maintain close contact with the child's diabetes team of professionals and to learn as much as possible about the disease and the symptoms to watch for in the child that may signal hyperglycemia. The parents of school-age children should make sure that teachers also understand the warning signs of hyperglycemia so that immediate medical attention can be given when needed.
American Diabetes Association Complete Guide to Diabetes: The Ultimate Home Reference from the Diabetes Experts, 3rd ed. New York: McGraw-Hill, 2002.
Becker, Gretchen. The First Year Type 2 Diabetes. New York: Marlowe, 2001.
Children's Hospital of Philadelphia Guide to Diabetes. New York: John Wiley & Sons, 2004.
ORGANIZATIONS
National Diabetes Education Program. One Diabetes Way, Bethesda, MD 20814–9692. Web site: <www.ndep.nih.gov>.
National Institute of Diabetes & Digestive & Kidney Diseases (NIDDK). NIH Building 31, Room 9A, 4 Center Drive,
MSC 2560, Bethesda, MD 20892–2560. Web site: <www.niddk.nih.gov>.
KEY TERMS
Antibody—A special protein made by the body's immune system as a defense against foreign material (bacteria, viruses, etc.) that enters the body. It is uniquely designed to attack and neutralize the specific antigen that triggered the immune response.
Autoimmune—Pertaining to an immune response by the body against its own tissues or types of cells.
Cerebral—Pertaining to the brain.
Coma—A condition of deep unconsciousness from which the person cannot be aroused
Diabetes—A disease characterized by an inability to process sugars in the diet, due to a decrease in or total absence of insulin production.
Edema—The presence of abnormally large amounts of fluid in the intercellular tissue spaces of the body.
Electrolytes—Salts and minerals that produce electrically charged particles (ions) in body fluids. Common human electrolytes are sodium chloride, potassium, calcium, and sodium bicarbonate. Electrolytes control the fluid balance of the body and are important in muscle contraction, energy generation, and almost all major biochemical reactions in the body.
Hypertonic saline solution—Fluid that contains salt in a concentration higher than that of healthy blood.
Ketones—Poisonous acidic chemicals produced by the body when fat instead of glucose is burned for energy. Breakdown of fat occurs when not enough insulin is present to channel glucose into body cells.
Metabolic—Refers to the chemical reactions in living organisms.
Osmolality—The concentration of osmolar particles in the blood (or other solutions) that can help determine if the body is dehydrated.
Physiologic—Refers to physiology, particularly normal, healthy, physical functioning.
WEB SITES
National Diabetes Information Clearing House (NDIC). Available online at <www.niddk.nih.gov> (accessed October 18, 2004).
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