Beyond body mass index: Body composition in children and adolescents with type 1 diabetes, clinical implications and perspectives

Table 1 Body-composition assessment methods in paediatric type 1 diabetes

Method	Accuracy	Reproducibility	Radiation	Cost/resources	Availability	Paediatric T1D validation	Regional fat	Serial monitoring
Anthropometry (BMI, WC, skinfolds)	Indirect assessment	High for height and weight, operator-dependent for WC and skinfolds	None	Minimal equipment	Widespread	Not applicable for direct body composition	Indirect central adiposity	Suitable for growth and weight trends only
BIA	Equation- and hydration-dependent estimates	Acceptable under standardized conditions with the same device	None	Dedicated device, lower resource requirements than imaging	Variable	Limited	Device-dependent indirect estimates, not interchangeable with MRI- or CT-measured VAT	Conditional on standardized protocol
DXA	Precise for total and regional tissues, not universal for all compartments	High within the same device and software	Low-dose	Specialized equipment and personnel	Selected centres	Limited	Trunk fat, VAT estimation with selected systems	Limited mainly by resources and access
MRI	Direct assessment of specific tissue compartments	High with standardized protocols	None	Specialized equipment and personnel	Specialized centres	Limited	Direct VAT, SAT and ectopic fat assessment	Limited mainly by resources and access
CT	High spatial resolution	High with standardized protocols	Ionizing radiation	Specialized equipment and personnel	Specialized centres	Not established	Direct VAT, SAT and muscle assessment	Unsuitable for routine serial monitoring
ADP	Model-based total FM and FFM assessment	Good under standardized conditions	None	Dedicated specialized equipment	Mainly research centres	Not established	None	Feasible but access-limited

Accuracy and reproducibility depend on the measured compartment, device, prediction algorithm and acquisition protocol. Cost and availability are described in relative terms because they vary across healthcare settings. T1D: Type 1 diabetes; BMI: Body mass index; WC: Waist circumference; BIA: Bioelectrical impedance analysis; MRI: Magnetic resonance imaging; CT: Computed tomography; VAT: Visceral adipose tissue; DXA: Dual-energy X-ray absorptiometry; SAT: Subcutaneous adipose tissue; ADP: Air displacement plethysmography; FFM: Fat-free mass; FM: Fat mass.