Original Article

Prevalence and Impact of Initial Misclassification of Pediatric Type 1 Diabetes Mellitus

Authors: Avnish Tripathi, MD, MPH, Ali A. Rizvi, MD, Lisa M. Knight, MD, Jeanette M. Jerrell, PhD

Abstract

Purpose: To characterize rates of initial misclassification of type 1 diabetes mellitus as type 2/unspecified diabetes mellitus in a cohort of children/adolescents and to examine the impact of misclassification on the risk of diabetes-related complications.


Methods: An 11-year dataset (1996–2006) was analyzed. Inclusion criteria included age 17 years and younger, enrollees in South Carolina State Medicaid, and diagnosis of type 2/unspecified or type 1 diabetes mellitus for at least two visits, 15 days apart. Survival analysis was used to assess the association of “misclassification” with the incidence of diabetic ketoacidosis (DKA), and the cumulative incidence of neuropathy, nephropathy, and cardiovascular complications, after controlling for individual risk factors and comorbid conditions.


Results: A total of 1130 individuals meeting the inclusion criteria were studied for a median of 7 years. Of the 1130 individuals, 669 (59.2%) maintained a diagnosis of type 2/unspecified diabetes mellitus, 205 (18.1%) were consistently diagnosed as type 1 diabetes mellitus, and the remaining 256 individuals (22.7%) were misclassified. Insulin treatment was used in 100% of the type 1 diabetes mellitus group and 73% of the misclassified group. Compared with the type 2 diabetes mellitus group, being misclassified was associated with earlier development of DKA (adjusted hazard ratio [aHR] 5.08, 95% confidence interval [CI] 3.09–8.37), neuropathy (aHR 1.94, CI 1.31–2.88), and nephropathy (aHR 1.72, CI 1.19–2.50), whereas being consistently classified with type 1 diabetes mellitus was associated only with earlier development of DKA (aHR 4.96, CI 2.56–9.61).


Conclusions: Proper categorization of pediatric diabetes can be challenging, especially with comorbid obesity. Failure to ascertain type 1 diabetes mellitus in a timely manner in a pediatric population may increase the risk of substandard care and diabetes-related complications.

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