title: The relation of serum 25-hydroxyvitamin-D levels with severity of obstructive sleep apnea and glucose metabolism abnormalities.
abstract: Obstructive sleep apnea (OSA) and 25-hydroxyvitamin-D₃ (25-OH-D) deficiency are two separate disorders associating with obesity, inflammation, and impaired glucose metabolism. We aimed to investigate the vitamin D status of OSA patients regarding to potential links between lower vitamin D levels and abnormal glucose metabolism, which is one of the main adverse outcomes of OSA. Study group is composed of 190 non-diabetic subjects who were suspected of having OSA. Subjects undergone polysomnography and were grouped due to apnea-hypopnea indices (AHI) as controls (AHI < 5, n = 47), mild OSA (5 ≤ AHI < 15, n = 46), moderate OSA (15 ≤ AHI < 30, n = 47), and severe OSA (AHI ≥ 30, n = 50). Serum 25-OH-D, HbA₁c, insulin levels were measured and 75-g oral glucose tolerance test was performed. Serum 25-OH-D level (ng/ml) of OSA patients were lower than control subjects (17.4 ± 6.9 vs. 19.9 ± 7.8), and decrement was parallel to severity of OSA; as 18.2 ± 6.4 (5 ≤ AHI < 15), 17.5 ± 7.4 (15 ≤ AHI < 30), and 16.3 ± 6.9 (AHI > 30), respectively (P = 0.097, r = -0.13). However, severe female OSA patients had significantly lower 25-OH-D levels (11.55 ng/ml), while control males had the highest mean value (21.7 ng/ml) (P < 0.001). Frequency of insulin resistance (IR) was 48%, prediabetes 41%, diabetes 16% in OSA patients. Mean 25-OH-D level of insulin resistant subjects (HOMA-IR ≥ 2.7, n = 77, AHI = 35.5) was lower than non-insulin resistant subjects (HOMA-IR < 2.7, n = 113, AHI = 19.8) as 16.18 ± 7.81 versus 19.2 ± 6.6, respectively (P = 0.004). 25-OH-D level of 91 non-diabetic subjects (n = 91, AHI = 19.7) was 19.5 ± 7.4, prediabetics (n = 75, AHI = 28.7) was 17.45 ± 6.9, and diabetics (n = 24, AHI = 46.3) was 13.8 ± 5.3 (P = 0.02). We showed that subjects with more severe OSA indices (AHI ≥ 15) tended to present lower vitamin D levels correlated to increased prevalence of IR, prediabetes, and diabetes. Vitamin D deficiency may play a role and/or worsen OSA's adverse outcomes on glucose metabolism. OSA patients may be considered for supplementation treatment which was shown to ameliorate abnormal glucose metabolism and inflammation.
authors.affiliation: Department of Endocrinology and Metabolism, Ankara Diskapi Yildirim Beyazit Training and Research Hospital, 06115 Altindag, Ankara, Turkey. nujencolak@yahoo.com
authors.forename: N Colak
authors.initials: NC
authors.lastname: Bozkurt
authors.forename: E
authors.initials: E
authors.lastname: Cakal
authors.forename: M
authors.initials: M
authors.lastname: Sahin
authors.forename: E Cakir
authors.initials: EC
authors.lastname: Ozkaya
authors.forename: H
authors.initials: H
authors.lastname: Firat
authors.forename: T
authors.initials: T
authors.lastname: Delibasi
mesh_terms: D015652:25-Hydroxyvitamin D 2 / Q000097:blood*; D000328:Adult; D002112:Calcifediol / Q000097:blood*; D003430:Cross-Sectional Studies; D003924:Diabetes Mellitus, Type 2 / Q000150:complications / Q000453:epidemiology; D005260:Female; D044882:Glucose Metabolism Disorders / Q000150:complications* / Q000453:epidemiology; D006442:Glycated Hemoglobin / Q000032:analysis; D006801:Humans; D007328:Insulin / Q000097:blood; D007333:Insulin Resistance; D008297:Male; D008875:Middle Aged; D011236:Prediabetic State / Q000150:complications / Q000453:epidemiology; D015995:Prevalence; D012720:Severity of Illness Index; D012727:Sex Characteristics; D020181:Sleep Apnea, Obstructive / Q000097:blood* / Q000150:complications* / Q000378:metabolism / Q000503:physiopathology; D014421:Turkey / Q000453:epidemiology; D014808:Vitamin D Deficiency / Q000150:complications* / Q000453:epidemiology
chemical_list: D015652:25-Hydroxyvitamin D 2; D002112:Calcifediol; D006442:Glycated Hemoglobin; D007328:Insulin; C517652:hemoglobin A1c protein, human