Double Diabetes: A growing diagnosis

October 10, 2005

Pharmacists may already have seen this: A child or adolescent with a diagnosis of Type 1 diabetes is suddenly getting prescriptions filled for metformin or rosaglitazone. No longer do all diabetes patients simply have either Type 1 or Type 2 diabetes. Instead, patients with established Type 1 can also incur insulin resistance and other markers of Type 2 disease, especially if risk factors like obesity are in place.

Several studies published in the October 2005 issue of Diabetes Care address this ominous overlap. In one study, investigators concluded that both autoimmunity and insulin resistance might coexist in obese children. The confluence of the pathophysiologies underlying Type 1 and Type 2 diabetes, respectively, has been dubbed "double diabetes." Why is double diabetes occurring, and what can pharmacists do to support families coping with it?

Although the reasons aren't completely understood, the lifestyle culprits that are making Type 2 diabetes more prevalent in the general population are also affecting people with Type 1 disease: excessive weight due to overeating and a sedentary life.

Because more children are obese and therefore more have insulin resistance, beta cells are failing in childhood rather than in adulthood, so that insulin resistance appears to cause diabetes of either Type 1 or Type 2 earlier, or both at once. Type 1 and Type 2 diabetes may even be the same disorder of insulin resistance but with different manifestations against different genetic backgrounds, according to the authors. "As pharmacists, we should be trying to attack the problem through behavioral changes in diet and exercise and I think ultimately through taking part in the research," said Rita Jew, Pharm.D., executive director of pharmacy services at Children's Hospital of Orange County, Calif.

Diagnosis of one may lead to diagnosis of the other

"We look at double diabetes from both angles-those with previously diagnosed Type 1 disease and those who have a diagnosis of Type 2," said Francine Kaufman, M.D., in an interview. Kaufman is the head of the Center for Diabetes and Endocrinology at Children's Hospital, Los Angeles, where she is a professor of pediatrics at the Keck School of Medicine at the University of Southern California.

For example, there is the scenario of the child who clearly has Type 1 diabetes, whose disease was diagnosed in the typical way. "As that child goes through the years and goes into puberty, he or she may end up gaining an excessive amount of weight, due to the typical regular U.S. lifestyle as well as genes," she said. In her practice, 25% of the children with Type 1 have either a first- or second-degree relative with Type 2 diabetes, she said. She noted that her practice serves a heavily Hispanic population, a group that has an increased risk of Type 2 diabetes, as do children of African descent. "When a child with Type 1 diabetes gains weight, he or she will require a larger amount of insulin in order to get a therapeutic dose." Therefore, the child is at risk of insulin resistance, she said. In addition, because of the pre-existing Type 1 diabetes, such a patient with excess weight is even more vulnerable to dyslipidemia, hypertension, and qualities of the metabolic syndrome.