Ysi 2300 stat plus glucose analyzer

Individuals completed two screening visits (Figure 1) to evaluate whether all inclusion criteria were met. During the initial screening visit, participants completed a fasting blood draw and anthropometric measures. They were also given instructions to record habitual dietary intake with 4‐day food intake records (3 weekdays and 1 weekend day). During the second visit, participants reviewed their 4‐day food intake records with a registered dietitian. Body weight was measured with a digital scale and height was measured using a stadiometer (Model 5002, Scale‐Tronix, Inc.). Brachial arterial pressure was measured in a seated position using automated sphygmomanometry (Press‐Mate BP 8800, Colin Medical Instruments Corp, San Antonio, TX, USA). Body composition was assessed via dual x‐ray absorptiometry (DXA, Lunar iDXA with enCORE version 17 software, GE Healthcare). Maximal oxygen consumption (VO_2max) was measured during incremental treadmill exercise to volitional fatigue using indirect calorimetry (ParvoMedics TrueOne 2400, Sandy, UT). Plasma glucose was measured via a YSI 2300 Stat Plus glucose analyzer (Yellow Springs Instruments, Yellow Springs, OH). Lipid and lipoprotein concentrations were measured in a certified commercial laboratory (Solstas Lab Partners, Roanoke, VA).

Serum and plasma were stored at −80°C until being assayed. Serum glucose was measured by glucose oxidative method (YSI 2300 Stat Plus Glucose Analyzer; Yellow Springs Instruments). Serum insulin levels were measured by enzyme-linked immunosorbent assay (ELISA) (Alpco Diagnostics, Salem NH). Serum testosterone and sex hormone binding globulin (SHBG) were measured via ELISA (Alpco Diagnostics). Free testosterone was calculated using the method of Södergard et al. [16 (link)]. DCI-IPG bioactivity was measured using an in-house bioactivity assay developed by the laboratory of JEN, as previously described [7 (link)].