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respectively. Two detector electrodes were placed at the posterior wrist between the styloid processes of the radius and ulna and at the anterior ankle between the tibial and fibular malleoli. The resistance and reactance measured at 50 kHz were used in the analysis, obtained by the program Hydra Data Acquisition Utility. With this technique, 2 body compartments, fat mass (FM)) and fat-free mass (FFM), can be determined.
- Dual Energy X-ray Absorptiometry
Subjects were scanned for 10 minutes in underwear while lying in the supine position with arms and legs abducted from the body. All measurements were whole body scans performed with a Hologic QDR-Delphi, S/N 45665. The DXA method measures 3 components of the body: bone mineral content (BMC), fat mass (FM) and lean tissue mass (LTM). These components were calculated based on the differential attenuations of the 2-photon beams, caused by the differences in density and chemical composition (22,23).
Energy expenditure
Resting oxygen consumption (VO2), and carbon dioxide production (VCO2) were measured by O2, CO2 flow with a ventilated hood system for 30 minutes with a metabolic monitor (Vmax Encore n29, Viasys Healthcare, Houten, the Netherlands) after an overnight fast. Before each test, the gas analysers were calibrated with 2 reference gas mixtures (16% O2, 4% CO2 and 26% O2 (Viasys)). The subjects were monitored during the measurements to prevent any movement or to sleep under the hood. The first 5 minutes were excluded to account for environment adjustment by the children and gas adaptation in the hood. Then resting energy expenditure (REE) was calculated from oxygen consumption and carbon dioxide production by using the equation of Weir (24).
Metabolic measurement
- Glucose tolerance and insulin resistance (Oral Glucose Tolerance Test)
After an overnight fast subjects were given glucose, in a dose of 1.75 g per kilogram of body weight (up to maximum of 75 g) orally, and blood samples are obtained after 0, 30 and 120 minutes for the measurement of plasma glucose and insulin levels. Impaired glucose tolerance was defined, according to the American Diabetes mellitus Association guidelines, as a fasting plasma glucose level between 5.6–6.9 mmol/l and a 2-hour plasma glucose level between 7.8-11.1 mmol/l. Type 2 diabetes mellitus was defined as a fasting glucose level of 7.0 mmol/l or higher or a 2-hour plasma glucose level of more than 11.1 mmol/l (25).
Questionnaires
After the Oral Glucose Tolerance Test (OGTT) participants complete the following questionnaires:
Study design
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