COPENHAGEN — Type 1 diabetes, traditionally considered a disease of wasting, is now frequently diagnosed in children who are overweight, according to a new study. That means determining which pediatric patient has type 1 diabetes and which has type 2 is getting harder, according to Dr. Ingrid M. Libman, of the department of pediatric endocrinology at the University of Pittsburgh.
“The problem now is that the lines are blurred between what we thought was clearly defined as type 1 and 2 diabetes,” said Dr. Libman in an interview. “The distinction can no longer be made based on phenotype.”
Data she presented at the annual meeting of the European Association for the Study of Diabetes showed that over 23 years of observation (1979–2002), the overall prevalence of overweight and obesity in children with newly diagnosed insulin-treated diabetes (traditionally considered type 1 disease) has more than tripled—doubling in African American children (from 30% to 62%) and quadrupling in white children (from 6% to 26%).
“In some cases we now have no clear way of distinguishing what kind of diabetes someone has based on how they look,” she said, adding that acanthosis nigricans, traditionally associated with type 2 diabetes, is now commonly found in overweight patients with type 1 disease as well.
Subjects diagnosed in period I (1979–1989) and period II (1990–98) were tested for beta-cell autoimmunity. In those with autoimmune positivity (known as diabetes type 1a), there was a similar increase in the prevalence of obesity between periods I and II: 6% to 21% among whites and 22% to 43% among African Americans. For period III (1999–2002), autoimmune antibodies are still being measured, she said. Autoimmune-negative subjects in the study may have had type 2 diabetes or type 1b—an insulin-dependent, nonautoimmune form of the disorder.
Dr. Libman said physicians might frequently face a new presentation of diabetes in which patients may actually have a confusing combination of characteristics.
“What we argue is that some kids may have characteristics of both type 1 and type 2 disease processes going on. If they are autoimmune positive, they have type 1a diabetes; however, if they are also overweight and have acanthosis nigricans, you could argue that they may also be insulin resistant.”
While establishing a clear diagnosis may often seem essential to physicians, Dr. Libman said that in the end, it might not be so important.
“If the child is really sick, does it matter if they have type 1 or 2? You will need to treat them with insulin. If they are overweight, not sick, and diagnosed randomly, you can likely control their blood sugars with lifestyle and metformin. If their antibodies come back positive, it doesn't mean you should start insulin—but you may need to monitor them more carefully and you may have a lower threshold for starting it.”
Overweight in children may not only make them more susceptible to developing type 2 disease, but in those who are genetically susceptible, it may also increase their risk or accelerate the development of type 1 disease—the concept of “double diabetes,” she said.