Effects of diabetes on learning in children.

OBJECTIVE Subtle neuropsychological deficits have been found in some children with type 1 diabetes. However, these data have been inconsistent, and it is not clear what the impact of these deficits might be on the learning of children with diabetes over time. The purpose of this study was to determine whether type 1 diabetes significantly interferes with the development of functional academic skills. It was hypothesized that 1) children with type 1 diabetes would demonstrate deficits in academic performance and behavior when compared with sibling or classmate control subjects and 2) that academic performance in children with type 1 diabetes would decline slightly but significantly over time whereas the performance of siblings or classmates would not. METHODS Three groups of children from 5 pediatric diabetes clinics in a primarily rural Midwestern state participated in this study: children with type 1 diabetes (n = 244), a sibling control group (n = 110), and an anonymous matched classmate control group (n = 209). The mean age of the children with diabetes was 14.8 years (standard deviation: 3.2) and of the siblings was 14.6 years (3.2); the mean grades were 8.1 (2.9) for the children with diabetes and 7.9 (3.1) for the siblings. The Hollingshead 2-factor index revealed that the children were from primarily middle- to upper-middle-class families. The mean age of onset of diabetes for the children with diabetes was 8.3 years (3.7) with a mean disease duration of 7.1 years (3.9). Because the matched classmate data were obtained anonymously, demographic information was not available on this group. Academic achievement was measured using both standardized tests and data on classroom performance. The standardized test data included scores from the Iowa Tests of Basic Skills (ITBS) for grades 3 through 8 and the Iowa Tests of Educational Development (ITED) for grades 9 through 12. Scores in 3 broad academic areas that are obtained on children of all ages were examined: math, reading, and core total (a composite score of reading, language, and math). ITBS/ITED data were obtained on all participants. School data including the number of days absent, school years repeated, and grade point averages for math and reading were obtained on the children with diabetes and their siblings. A short, 50-item screening scale (PBS-50d), adapted from the longer 165 item Pediatric Behavior Scale (PBS), was completed by the parents to obtain information on the behavioral characteristics of the children with diabetes and their siblings. Diabetes variables measured included metabolic control (HbA1c), age at onset, and disease duration. This study looked at both the current academic performance of children with diabetes and their performance over time in relation to 2 control groups: siblings and matched classmates. A cross-sectional approach was used to evaluate current performance. Statistical differences between groups were evaluated using matched t tests or McNemar's test for differences between related samples as appropriate. Differences across time were evaluated using hierarchical linear modeling. Comparisons of ITBS/ITED test scores across grades used national percentile ranks that were converted to standard scores (SS) with a mean of 100 and a standard deviation of 15. Students in this study performed above the national average, which is typical of students in the state where this study was conducted. Data from participating clinics were compared, and no differences in current achievement scores, grade point averages, or socioeconomic status were noted for either children with diabetes or their siblings. Therefore, all subsequent analyses used data combined from all sites. RESULTS Current academic performance on the ITBS/ITED did not show lower performance by children with diabetes compared with either control group; in fact, children with diabetes performed better than their siblings on math (mean SS: 115.0 vs 111.1) and core total scores (mean SS: 113.9 vs 110.5) and better than their matched classmates on reading (mean SS: 108.9 vs 106.8). When subgroup comparisons based on diabetes metabolic control were made among children with diabetes, poorer academic performance tended to occur in children with poorer diabetic control. However, this pattern was also noted in sibling scores when the siblings were grouped on the basis of the level of diabetic control of their brother or sister with diabetes. Children with diabetes had significantly more school absences (Mean = 7.3 per year) than their siblings (M = 5.3) and more behavioral problems. Behaviorally, the 2 groups did not differ on the 4 general factors of Aggression/Opposition, Hyperactivity/Inattention, Depression/Anxiety, and Physical Complaints. However, children with diabetes did differ significantly from their siblings on items that reflected compliance, mood variability, and fatigue, but not learning. These were 4 areas included in the PBS-50d to reflect potential concerns for children with diabetes. Academic achievement growth curves for the ITBS/ITED for each group revealed no statistically significant differences between groups when tested using hierarchical linear modeling. Individual differences in the growth trajectories were too small and inconsistent to be detected. CONCLUSIONS For most children, type 1 diabetes is not associated with lower academic performance compared with either siblings or classmates, although increased behavioral concerns are reported by parents. The results of this study suggest that the subtle cognitive deficits often documented in children with type 1 diabetes may not significantly limit the functional academic abilities of these children over time. However, careful monitoring is still needed to ensure that episodes of hypoglycemia associated with seizures are not adversely affecting learning.