Evaluation of immunoassays for the measurement of insulin and C-peptide as indirect biomarkers of insulin misuse in sport: Values in selected population of athletes

Expanded test method for peptides >2 kDa employing immunoaffinity purification and LC‐HRMS/MS

“…The internal standard 1 (ISTD 1) [[ 2 H 10 ] Leu B6,B11,B15,B17 ]-Insulin (human) was purchased from PeptaNova (Sandhausen, Germany). Synacthen Depot 1 mg was from Novartis Pharma (Bern, Switzerland) and the labelled analogue [[ 2 H 8 ] Val 13,20,22 ]-synacthen (ISTD 2) was obtained from BMFZ (Düsseldorf, Germany). CJC-1295 and CJC-1293 were a custom synthesis from Centic Biotec (Jena, Germany).…”

“…were also available for each of these target peptides. Unfortunately, these assays were unable to multiplex peptides and potentially suffer from cross‐reactivities to the synthetic analogues or metabolites . Noteworthy, these methods represent highly sensitive assays with the ability to screen for a large number of samples in a short time.…”

Annual banned‐substance review: analytical approaches in human sports drug testing

“…Following an intra-and interlaboratory validation of corresponding immunoassays, a comprehensive study concerning different groups of elite athletes (swimming, synchronized swimming, taekwondo, rhythmic gymnastics, triathlon, and weightlifting) as well as recreational sportsmen and sedentary www.drugtestinganalysis.com individuals was conduced. [66] The results demonstrated significantly elevated IGF-2 levels in elite and recreational athletes compared to the sedentary control group, and high-profile sportsmen showed decreased IGFBP-2 and increased IGFBP-3 compared to all other tested volunteers. Moreover, IGFBP-3 and ICTP values were found to be sport-dependent, and IGFBP-2 and -3 further varied seasonally.…”

Association between physical activity and serum C‐peptide levels among the elderly

“…Age‐related elevated serum C‐peptide levels are possibly a result of decreased total insulin clearance, and age‐related decreases in β‐cell mass and insulin resistance have been widely reported . However, experience has shown that regular physical activity can improve insulin sensitivity and increase insulin clearance . The Zutphen elderly study reported a negative association between the current physical activity level and serum insulin level, but no association with the serum C‐peptide level .…”

“…24,25 However, experience has shown that regular physical activity can improve insulin sensitivity and increase insulin clearance. 26,27 The Zutphen elderly study reported a negative association between the current physical activity level and serum insulin level, but no association with the serum C-peptide level. 28 Some studies have also shown that serum C-peptide might increase blood and renal flow during exercise.…”