Normal total and high molecular weight adiponectin levels in adults with cystic fibrosis

Cystic fibrosis related diabetes (CFRD) is an important complication of CF that increases mortality. Adiponectin, an adipokine secreted from adipose tissue, plays an important role in fatty acid and glucose metabolism. Lower total adiponectin (TA) levels have been linked to the risk of developing type 2 diabetes. However, studies show that the high molecular weight isoform (HMW), thought to be more active than TA, might be a better indicator of insulin sensitivity. Our aim was to determine the association between HMW and insulin sensitivity in CF subjects and determine if other factors might modulate its levels. Thirteen control subjects and 47 CF adults (16 with normal glucose tolerance, 16 prediabetic and 15 with CFRD) underwent an oral glucose tolerance test. Blood samples were taken at time 0, 30, 60, 90 and 120 min. Body mass index, fibrinogen, glucose and insulin, TA and HMW were measured in every subject. Regression analysis was used to determine the association between TA, HMW and glucose (fasting glucose, 2h glucose and glucose AUC) as well as insulin (fasting insulin, insulin AUC, and Stumvoll insulin sensitivity index) parameters. TA and HMW levels were similar between CF patients and controls and were not associated to insulin sensitivity. TA was negatively associated to insulin AUC (p=0.0108) and 2h glucose (p=0.0116) in controls while these relationships were either weakly negative (p=0.0208) or weakly positive (p=0.0105) in CF patients. Also, HMW was negatively associated to insulin (p=0.00301) and glucose AUC (p=0.0546) in controls whereas these associations were positive in CF patients (p=0.0388, p=0.0232 respectively). In conclusion, our exploratory study on HMW adiponectin demonstrated similar levels of TA and HMW between CF patients and controls and different relationships between forms of adiponectin to glucose metabolism and insulin in CF.