I have been on service at Children's National Medical Center this past week. This means I am the physician that admits children and adolescents with new onset diabetes. As we are a tertiary children's hospital, many of our children are referred from great distances to both confirm the diagnosis and then treat accordingly. It is extremely important to be sure that the diagnosis of diabetes is appropriate before telling the family that their child/adolescent now has a chronic and incurable (as of now) illness. After this busy week where we had many children with both new onset type 1 and type 2 diabetes as well as children with high blood sugars that did not have diabetes, I wanted to take the opportunity to review the diagnosis of diabetes. In other words, how to distinguish between hyperglycemia caused by other reasons versus new onset diabetes.
Currently, there are four ways to diagnose diabetes (both type 1 and type 2):
1. Symptoms of increased urination, increased drinking, increased appetite and weight loss in association with a random blood sugar greater than 200 mg/dl.
2. Fasting blood sugars greater than 126 mg/dl on 2 separate occasions.
3. Oral glucose tolerance test (75 grams of carbohydrates) with resulting 2-hour post-prandial blood sugar greater than 200 mg/dl. (Note: different carb amounts are utilized for diagnosis of "gestational diabetes.")
4. Hb A1c greater than 6.5 percent (note that the hb A1c may not always be accurate in adolescents).
Pediatric healthcare teams usually see children/adolescents who present with the first cluster of symptoms and random blood sugars greater than 200 mg/dl. This is because the overwhelming majority of children are diagnosed with type 1 diabetes (Children's National statistics: 89 percent type 1 diabetes and 11 percent type 2 diabetes). Children and adolescents that present with either fasting blood sugars greater than 126 mg/dl or abnormal glucose tolerance tests often have type 2 diabetes although it is important to remember that children with type 2 diabetes can have symptoms identical to those with type 1. In our practice, the hb A1c is a useful adjunct to the diagnosis of diabetes but we do not totally rely on it as the definitive answer. The hb A1c is often very useful to distinguish between new onset diabetes and hyperglycemia from other reasons.
What are the situations in which hyperglycemia might occur in children and adolescents who do not have new onset diabetes?
1. Stress-induced hyperglycemia: These children are often very ill with an underlying condition. Examples include infections that cause a high fever, and those situations in which the body produces a burst of counter-regulatory hormones including adrenalin, cortisol, growth hormone and glucagon to "raise" blood glucose to fight the offending intruder. These children are often quite sick with concomitant high blood sugars. If we ask about the symptoms associated with diabetes, such as increased urination, families are often uncertain.