Introduction: Obstructive sleep apnoea (OSA) is reported to have effects on a number of hormone systems including glycaemic control, catecholamines, and the HPA axis. In this study we aimed to determine the impact of OSA on IGF-I levels.
Patients & Methods: This is a prospective cohort study performed at Leeds Teaching Hospitals. Patients were recruited from the Sleep Apnoea Clinic between November 2014 and May 2017, following diagnosis of OSA. Serum samples were taken for measurement of IGF-I, and data collected on BMI, apnoea-hypoapnoea index (AHI) as a severity of OSA.
Results: 448 participants were recruited (68% male, 32% female) with a mean age of 53.3±12.6 years and a mean BMI of 36.0±7.8 kg/m2. T2DM was present in 77(17.2%), and pre-diabetes in 25(5.6%). The severity of OSA as assessed at the time of the study was as follows: 9 patients (2%) without current evidence of OSA; 122 (17.2%) with mild OSA; 117 (26.1%) with moderate OSA and 200 (44.7%) with severe OSA.
A positive correlation was demonstrated between OSA severity and both BMI r=0.177 (P=0.0005) and age; r=0.106 (P=0.0245), and a negative correlation between OSA severity and female gender; r=−0.155 (P<0.001). Although IGF-I levels were dependent on BMI; r=−0.153 (P=0.002), no association could be shown with OSA severity; r=−0.02 (P=0.57).
In a multiple linear regression analysis IGF-1 was predicted by age (coefficient 0.459, P<0.001) and BMI (coefficient −0.461, P=0.027), but not by OSA severity, gender, or presence of diabetes. OSA severity was predicted by BMI (coefficient 0.027, P<0.001), gender (coefficient −0.45, P<0.001) and age (coefficient 0.01, P=0.005), but not by IGF-1 or presence of diabetes.
Conclusion: Serum levels of IGF-I are dependent not only on age, but also BMI, with IGF-I being lower with increasing BMI. No significant effect of OSA on IGF-I levels could however be determined.