Effect of hypoxia on glucose metabolism in nondiabetic patients with obstructive sleep apnea syndrome.

AIM: Obstructive sleep apnea syndrome (OSAS) may promote hyperglycemia and insulin resistance. Our aim is to investigate the effect of OSAS on the fasting plasma glucose, glycosylated hemoglobin (HbA1c), and C reactive protein (CRP) in nondiabetic patients.

MATERIAL AND METHODS: Blood parameters of consecutive 90 non diabetic patients whom polysomnografic evaluations were done in our sleep laboratory was evaluated. Among these 61 patients with normal fasting blood glucose were classified due to their apne-hipopnea index (AHI) as mild (n=16, 26.2%), moderate (n=18, 29.5%) and severe (n=27, 44.2%) OSAS. The fasting plasma glucose, HbA1c and CRP were measured.

RESULTS: Mean age of the patients was 47.7±11.2 years, 72% male. HbA1c, fasting glucose levels show positive correlation with BMI (r=.503, P=.00; r=.258, P=.045). No relation of HbA1c to apnea index nor AHI was detected while positive corelation of fasting glucose and CRP was detected (r=.262, P=.042; r=.258, P=.045). HbA1c, fasting glucose and CRP levels show negative correlation with minimum SpO2 levels (by order of r=-.302, P=.018; r=-.368, P=.004; r=-.365, P=.004). HbA1c, fasting glucose levels and CRP levels show positive correlation with mean desaturation index (time duration in which SpO2<90% by pulse oxymeter) (r=.263, P=.041; r=.311, P=.015; r=.283, P=.027).

CONCLUSIONS: Although no relation in between increased HbA1c or glucose levels and severity of OSAS was detected in nondiabetic OSAS patients, the correlation with the night hypoxia was detected. This could also show the effect of night time hypoxia on glucose metabolism in OSAS patients.