Diabetes

By Afshan Chaudhry, MD, and Ivan Zador, MD
Pediatric Endocrinology Department, Marshfield Clinic

The incidence of childhood type I diabetes is rising worldwide. The rise appears to be primarily in younger children. In the United States, the incidence of type I diabetes is rising in most age and ethnic groups especially in children younger than 5. Younger children are more vulnerable compared to older children because they are not able to compensate for pathologic processes by obtaining fluids and increasing fluid intake to replace ongoing urinary losses. Consequently, children younger than 6 are more likely to present with DKA because health care personnel and families are less likely to suspect diabetes in this age group, leading to a prolonged duration of illness and more severe metabolic decompensation before diagnosis.

It is often difficult to recognize the symptoms of hyperglycemia in younger children, especially those younger than 2. Polyuria and polydipsia are difficult to detect in diaper-clad children who are unable to communicate their thirst. History or presence of prolonged or recurrent candidal infection (usually in the diaper area) is an important clue that should raise suspicion about the possibility of diabetes mellitus. Candidal infection was present at diagnosis in a significant proportion of children, especially those younger than 2. In this vulnerable age group, a high index of suspicion is required for early diagnosis. When a young child presents for evaluation of dehydration, abdominal pain, or fatigue, the clinician should include diabetes in the differential diagnosis and consider measuring serum glucose and testing for glycosuria.

The classic symptoms are caused by hyperglycemia and include polyuria, polydipsia, weight loss despite increased appetite initially (polyphagia), and lethargy. As ketoacidosis sets in, they can develop anorexia, nausea, vomiting, and abdominal pain, which at times can mimic appendicitis or gastroenteritis. Hyperventilation and deep (Kussmaul) respirations represent the respiratory compensation for metabolic acidosis. Neurologic findings, ranging from drowsiness, lethargy, and obtundation, to coma, are related to the severity of hyperosmolality and/or to the degree of acidosis. Cerebral edema occurs in 0.5 to 1 percent of cases of DKA in children, and is the leading cause of mortality.

The diagnosis of diabetes mellitus is based upon:

1. Fasting plasma glucose ≥126 mg/dL. Fasting is defined as no caloric intake for at least eight hours.
2. Symptoms of hyperglycemia and a random venous plasma glucose ≥200 mg/dL.
3. Abnormal oral glucose tolerance test (OGTT) defined as a plasma glucose ≥200 mg/dL measured two hours after a glucose load of 1.75 g/kg (maximum dose of 75 g).Most children and adolescents are symptomatic and have plasma glucose concentrations well above ≥200 mg/dL; thus, OGTT is seldom necessary to diagnose type 1 diabetes. If patient is asymptomatic, then we need 2 abnormal oral glucose tolerance tests to diagnose diabetes.
4. Glycated hemoglobin (A1C) ≥ 6.5 percent (using an assay that is certified by the National Glycohemoglobin Standardization Program).

If a patient is asymptomatic and has abnormal fasting glucose or oral glucose tolerance test, then we have to repeat testing.