Correlation Analysis Of Vitamin D And Parathyroid Hormone With Insulin Resistance In OSAHS

BackgroundVitamin D insufficiency and/or high levels of parathyroid hormone(PTH)seem to be associated with abnormal glucose metabolism,which is frequent in obstructive sleep apnea hypopnea syndrome(OSAHS).The purpose of this study was to investigate vitamin D and PTH concentrations in OSAHS,and to explore potential associations between vitamin D,PTH and insulin resistance(IR).MethodsOne hundred and sixty-nine subjects who with sleep snoring were recruited consecutively,and evaluated by polysomnography(PSG)to determine the number of apnea and hypopnea episodes per hour of sleep(apnea/hypopnea index:AHI).OSAHS was diagnosed for AHI>5.Average(A-SPO2)and minimum pulse oxygen saturation(M-SPO2)were assessed during PSG as indices of nocturnal hypoxemia.After overnight fasting,a standard 75 g oral glucose tolerance test was performed.Serum 25-hydroxyvitamin D,PTH,fasting glucose and fasting insulin were also measured.Homeostasis model assessment(HOMA)was used to evaluate IR:HOMA-IR=fasting plasma insulin×fasting plasma glucose/22.5,with "insulin resistance" defined as HOMA-IR>2.7.ResultsPatients were classified into 4 groups according to AHI:control group(AHI<5,n=21),mild OSAHS(5?AHI<15,n=21),moderate OSAHS(15?AAHI<30,n=44),and severe OSAHS(AHI?30,n=83).They were also classified,according to HOMA-IR,as insulin-resistant(HOMA-IR>2.7,n=96)or non-insulin-resistant(HOMA-IR?2.7,n=73).There was significant difference in vitamin D levels between AHI groups(p=0.028),but no significant difference was found in PTH.HOMA-IR was significantly higher in severe OSAHS than in controls(P=0.001).Vitamin D concentration correlated negatively with AHI(r=-0.222,P=0.004)and with HOMA-IR(r=-0.358,P<0.001).PTH concentration correlated negatively with vitamin D concentration(r=-0.323,P<0.001)and correlated positively with AHI(r=0.247,P=0.001),HOMA-IR(r=0.229,P=0.003).HOMA-IR correlated positively with AHI(r=0.365,P<0.001).Finally,Logistic regression showed that vitamin D concentration(?=-0.184,P<0.001)and BMI(?=0.230,P=0.002)were independently associated with HOMA-IR.ConclusionSubjects with severe OSAHS may have a low vitamin D level associated with increased risk of IR.Vitamin D was independently associated with IR in OSAHS.Vitamin D insufficiency may play a role in the pathogenesis of IR in OSAHS.