Session: SAT 677-696-Obesity Physiology & Epidemiology
Poster Board SAT-689
To assess the classification of youth with T1D as overweight and obese using BMI %iles (≥85 to <95th %ile and ≥95th %ile, respectively), we compared against adiposity measured by Dual-energy X-ray Absorptiometry (DXA, Hologic Delphi™ A) in 126 youth, ages 8-17, with T1D. Youth (49% male, 89% white) were 12.9±2.5 (mean±SD) years old and had T1D for 5.9±3.2 years; mean A1c was 8.1±1.1% and 72% received insulin pump therapy. CDC standards from 2000 provided BMI %iles based on youth height and weight. Body composition, reported as percent body fat (%BF), was measured by DXA using standardized protocols. We calculated age- and sex-based cut-points for overweight and obesity by %BF derived from Taylor et al, 2002. Statistical analyses included Pearson correlations and chi-square.
Mean BMI %ile was 71±23 (range 5-99.5); mean %BF was 27.7±8.0% (range 11.5-47.5%). BMI %ile and %BF were moderately correlated (r=0.52, p<.0001), with strongest correlations in pre-pubertal youth (n=40, r=0.72, p<.0001) and weakest in post-pubertal youth (n=32, r=0.30, p=.09). According to BMI %iles, 67% of T1D youth were normal weight, 20% were overweight, and 13% were obese. According to %BF, 48% of T1D youth were normal weight, 43% were overweight, and 9% were obese. The weight status of 38% of T1D youth was differentially classified by BMI %ile Vs DXA measurements of %BF, with 2/3 of discordant classifications resulting from an insensitivity of BMI %ile to detect overweight/obesity; BMI %ile classified fewer youth as overweight/obese Vs %BF. While rates of discordant classification were similar by sex and across pubertal stages, differential classification differed by pubertal status (p<.02). In pre-pubertal youth, discordant classification was mainly due to insensitivity of BMI %ile to detect overweight/obesity (89%); in post-pubertal youth, discordant classification was mainly due to overestimation of adiposity by BMI %ile compared with %BF (58%).
Overall, 49% of overweight/obese T1D youth determined by DXA were classified as normal weight by BMI %ile, potentially resulting in missed opportunities to intervene with diet and exercise to manage weight and reduce cardiovascular risk in the already vulnerable population of T1D youth.
Disclosure: LML: Advisory Group Member, Bristol-Myers Squibb, Advisory Group Member, Sanofi, Consultant, Johnson &Johnson, Consultant, LifeScan/Animas, Consultant, Eli Lilly & Company, Consultant, Menarini. Nothing to Disclose: CB, MLH, TRN, LML, LKV, SNM
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