Diabetes
Stuart A. Weinzimer
INTRODUCTION
Diabetes mellitus is a disorder of glucose metabolism characterized by hyperglycemia caused by insulin deficiency. Diabetes encompasses several clinical syndromes including, but not limited to, type 1 diabetes mellitus (T1D), characterized by rapid onset, a tendency toward ketoacidosis, and absolute insulin deficiency; and type 2 diabetes (T2D), associated with obesity, insulin resistance, a lesser likelihood of ketoacidosis, and nonabsolute dependence on insulin for survival. Both types of diabetes are associated with similar long-term complications. T1D affects ˜1 in 350 children by the age of 18 and is more common in children of European background. T2D is more commonly seen in African American, Native American, and Latino children, but its prevalence is increasing in all ethnic groups.
DIFFERENTIAL DIAGNOSIS LISTInfectious Disorders
Urinary tract infection (UTI)
Gastroenteritis
Pneumonia
Sepsis
Toxic Disorders
Salicylate ingestion
Steroid use
Diuretic use
Endocrine and Metabolic Disorders
Hypercalcemia
Diabetes insipidus
Inborn error of metabolism
Miscellaneous Disorders
Renal glucosuria
Stress hyperglycemia
Psychosocial Disorders
Psychogenic polydipsia
Enuresis
EVALUATION OF DIABETES
Patient History
Polyuria, polydipsia, and polyphagia are classic symptoms:
Physical Examination
Physical examination is usually normal early in the course of disease. Later findings can include the following:
Signs of dehydration (e.g., tachycardia, poor skin perfusion, hypotension)
Hyperpnea (Kussmaul respirations), a sign of metabolic acidosis
Fruity odor to the breath, a sign of ketosis
Laboratory Studies
The diagnosis of diabetes may be made in one of four ways:
Fasting blood glucose (BG) level ≥ 126 mg/dL
Random BG level≥200 mg/dL in the setting of symptoms of diabetes
Two-hour BG level ≥200 mg/dL during an oral glucose tolerance test
Hemoglobin A1c level≥ 6.5%
The presence of glucose in the urine is suggestive but NOT diagnostic for diabetes.
Other biochemical parameters may be normal until the development of DKA, at which time:
Serum electrolyte panel may reveal hyponatremia (sodium level <136 mEq/L) from hyperglycemia and hypertriglyceridemia; hypokalemia or hyperkalemia (potassium level <4.0 mEq/L or >6.0 mEq/L, respectively), or a metabolic acidosis (bicarbonate level <15 mEq/L).
Arterial or venous blood gases may reveal a metabolic acidosis (pH <7.3, partial pressure of carbon dioxide [Pco2]<35 mm Hg).
Complete blood cell count may reveal elevated white blood cell count even in the absence of infection.
DIFFERENTIAL DIAGNOSIS
UTI and nocturnal enuresis. The early signs of diabetes (i.e., polyuria, nocturia) may be mistaken for UTI or nocturnal enuresis. Urinalysis, however, demonstrates the presence of glucose and ketones and the absence of markers of infection.
Renal glucosuria (a condition in which glucose is excreted in the urine at normal BG levels) may be mistaken for diabetes. Diabetes should never be diagnosed by the presence of glucosuria alone: An elevated BG or hemoglobin A1c level is required for the diagnosis of diabetes.
Other metabolic disorders may present with acidosis and dehydration, but a history of polyuria, polyphagia, and weight loss with an elevated BG is characteristic of diabetes.
Gastroenteritis and surgical abdomen. The abdominal pain and vomiting of DKA may be mistaken for gastroenteritis or a surgical abdomen, but DKA may be
differentiated not only from these disorders but also from other metabolic diseases by the distinct history of polyuria, polydipsia, and a characteristic fruity odor to the breath.
differentiated not only from these disorders but also from other metabolic diseases by the distinct history of polyuria, polydipsia, and a characteristic fruity odor to the breath.
Intercurrent febrile illnesses or the administration of glucocorticoids for inflammatory conditions may cause an insulin-resistant state and precipitate hyperglycemia, glucosuria, and even small amounts of ketonuria (known as “stress hyperglycemia”). These conditions must be differentiated from true diabetes. In patients who do not have diabetes, resolution of the fever and acute illness or discontinuation of the medications should result in normalization of the blood sugar. It is important to go back and determine whether the typical symptoms of polydipsia and polyuria are present. In the absence of these symptoms, the diagnosis of diabetes is less likely. Occasionally, however, a latent case of true diabetes may be discovered. In these cases, the presence of anti-islet cell antibodies or an elevated hemoglobin A1c value may be useful in establishing the proper diagnosis.
Asthma or pneumonia. The Kussmaul respirations that occur with progressive acidosis may resemble asthma or pneumonia, but auscultation and radiography reveal clear lung fields.
TREATMENT OF DIABETES
Optimal care requires the efforts of the child, the family, and a team of physicians, nurses, dietitians, and counselors specializing in the treatment of children with diabetes. The physician’s primary responsibilities are the prompt recognition of symptoms leading to a definitive diagnosis, referral to a pediatric diabetes center, and continued supervision of the child’s medical care. Children with diabetes should attend a multidisciplinary pediatric diabetes center at least every 3 months or more frequently if treatment goals are not being met.
Treatment goals are the maintenance of BG and hemoglobin A1c levels as close to normal as possible, avoidance of severe hypoglycemia, and optimization of the child’s normal physical and psychosocial growth and development. To accomplish these goals, the child must not only take insulin or oral antidiabetic medications but also monitor the blood sugar several times during the day, exercise, and adhere to the prescribed meal plan. Family members should be trained to monitor blood sugars, give insulin, recognize and treat low blood sugar reactions, and provide support. Psychosocial factors are critical in the management of children with diabetes, and potential problems should be addressed by experienced behavioral or family therapists.
Insulin
The goal of diabetes therapy is to maintain the BG levels as close to normal as possible. For the child with T1D, this means reliance on multiple doses of insulin daily. These may be administered either by subcutaneous injections via syringe or via continuous subcutaneous insulin infusion using a portable wearable pump (insulin pump therapy). In both cases, insulin dosages are customized to mimic the body’s pattern of basal insulin delivery between meals and overnight, with spikes in insulin release (boluses) for meal-related carbohydrates. Insulin doses
must be individually titrated, and even in one individual, insulin needs typically change from day to day because of variations in meals, physical activity, illness, and other factors. Table 26-1 shows the most commonly used insulin preparations. Table 26-2 gives recommended insulin adjustments.
must be individually titrated, and even in one individual, insulin needs typically change from day to day because of variations in meals, physical activity, illness, and other factors. Table 26-1 shows the most commonly used insulin preparations. Table 26-2 gives recommended insulin adjustments.
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