Cross-sectional and longitudinal relationships of body mass index with glycemic control in children and adolescents with type 1 diabetes mellitus

Abstract

Aims: Weight gain is an oft-cited outcome of improved glycemic control in adults with type 1 diabetes, though few studies have investigated this in youth. The purpose of this paper was to examine cross-sectional and longitudinal associations of body mass index (BMI, kg/m(2)) with glycemic control in youth with type 1 diabetes (n=340, 12.5 ± 1.7 year, 49% female, duration ≥ 1 year) participating in a 2-year multi-center intervention study targeting family diabetes management.

Methods: BMI was calculated from height and weight measured at clinic visits. Glycohemoglobin (HbA1c) at each visit was assayed centrally. Cross-sectional associations of baseline BMI with glycemic control, and of change in BMI and HbA1c with baseline values, were examined. Longitudinal associations of time-varying BMI and HbA1c were examined using a multilevel linear mixed effects model controlling for time-varying time (months), insulin dose (units/kg/day), regimen, Tanner stage, and time invariant baseline diabetes duration, BMI, treatment group and sociodemographic characteristics.

Results: Baseline HbA1c was unrelated to baseline BMI, but was related positively to subsequent BMI change (p=0.04) and inversely to HbA1c change (p=0.002). Baseline BMI was inversely related to BMI change (p=0.01) and unrelated to HbA1c change. In multilevel regression, BMI was related inversely to HbA1c (%) (β ± SE=-0.11 ± 0.02, p<0.001) and positively to insulin dose (0.23 ± 0.07, p=0.001). In the treatment group only, BMI was positively related to pump regimen (0.18 ± 0.08, p=0.02).

Conclusions: Increased insulin administered to improve glycemic control may contribute to increased BMI in youth with type 1 diabetes, indicating the importance of determining ways to minimize weight gain while optimizing glycemic control.

Trial registration: ClinicalTrials.gov NCT00273286.

Published by Elsevier Ireland Ltd.

Figures

Figure 1. Change in BMI and glycemic control by baseline values

(A) Change in BMI (kg/m2) (p=0.04) and HbA1c (mmol, %) (p=0.002) by baseline HbA1c category (≤8.0%, 64 mmol/mol, versus >8.0%, 64 mmol/mol) and (B) change in BMI (p=0.01) and HbA1c (p=0.59) by baseline weight category (low=BMI%ile<85; overweight=BMI%ile ≥85, <95; obese=BMI%ile≥95). Same subscripts indicate significantly different (p<0.05) pairwise differences adjusted for multiple comparisons (B only).