Major Finding: Some 61% of children and adolescents initially diagnosed with type 2 diabetes maintained a diagnosis of type 2 diabetes over a median of 7 years, while 39% were reclassified as having type 1 diabetes.
Data Source: A study of 4,070 subjects aged 17 years and younger enrolled in the South Carolina State Medicaid Program who had at least two initial service encounters with an ICD-9 diagnosis of type 2 diabetes in 1996-2006.
Disclosures: Dr. Tripathi said that he had no relevant financial disclosures.
SAN DIEGO – More than a third of type 1 diabetes cases in a large pediatric Medicaid population were misdiagnosed as having type 2 early in management, results from a 10-year analysis showed.
Such misclassification “may be associated with significantly increased risk of life-threatening, but potentially preventable, acute complications such as diabetic ketoacidosis,” Dr. Avnish Tripathi said at the meeting. “These findings have implications for primary health care of diabetes and reiterate the importance of performing laboratory tests such as autoantibody titers and C-peptide levels for establishing type 1 diabetes pathology earlier in the clinical management process,” said Dr. Tripathi, a doctoral candidate in public health at the University of South Carolina, Columbia.
Misclassification can occur both ways, he added. Pediatric diabetes is usually assumed to be type 1, so “it may be diagnosed as such even if characteristics point to type 2 diabetes.” But increased awareness of type 2 diabetes in the pediatric population means that “type 1 diabetes in overweight or obese patients may be diagnosed as type 2 diabetes.”
The researchers analyzed data from 4,070 subjects aged 17 years and younger enrolled in the South Carolina State Medicaid Program who had at least two initial service encounters with an ICD-9 diagnosis of type 2 diabetes in 1996-2006. They also evaluated ICD-9 codes for comorbid medical complications such as obesity and dyslipidemia, and for vascular and other complications such as diabetic ketoacidosis.
Of the 4,070 children and adolescents, more than half (57%) were female, 56% were non-Hispanic black, their median age was 8 years, and they were followed for a median of 7 years. Dr. Tripathi reported that 2,489 of the subjects (61%) maintained a diagnosis of type 2 diabetes over time, whereas 39% were later reclassified as having type 1. After adjustment for variables, older age at diagnosis increased the risk of misclassification (odds ratio, 1.66), while being obese or overweight decreased the risk of being in the misclassification group (OR, 0.79).
Compared with those who maintained a type 2 diagnosis, a significantly higher proportion of misclassified youth were treated with insulin (82% vs. 2%, respectively), and went on to develop dyslipidemia (P less than .001) and hypertension (P = .0001). Misclassified youth also had a 50-fold increased risk of at least one incidence of diabetic ketoacidosis (OR, 49.5), nearly a 4-fold increased risk of developing cumulative diabetic neuropathy (OR, 3.75), a higher risk of cumulative renal complications (OR, 1.27), and a lower risk of developing cardiac conditions (OR, 0.81).
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New Criteria Needed for Type 2 Dx
This concept is not new, and there have been a number of publications over the past decade regarding the difficulty in clinically separating type 1 and type 2 diabetes, as at least one-third of type 1 patients in our series are overweight or obese at diagnosis (Pediatr. Diabetes 2003;4:110-3; Diabetes Care 2003;26:2876-82; Diabetes Care 2003;26:2871-5). These findings have since been confirmed by the TODAY (Treatment Options for Type 2 Diabetes in Adolescents and Youth) study and the SEARCH for Diabetes in Youth study. In the current study, I found it difficult to evaluate what the criteria for the reclassification were.
The message to pediatricians, general practitioners, and diabetologists should be that being obese does not protect the patient from type 1 diabetes, and thus, there need to be other criteria to make the diagnosis of type 2 in children.
DOROTHY BECKER, M.D., is professor of pediatrics and director of endocrinology and diabetes at Children's Hospital of Pittsburgh and the University of Pittsburgh, who was asked to comment on Dr. Tripathi's findings. Dr. Becker said she had no relevant financial disclosures. Her 2003 series of diabetes studies was funded by the National Institutes of Health.