Int J Diabetes Dev Ctries DOI 10.1007/s13410-014-0281-0
ORIGINAL ARTICLE
Obstructive sleep apnea and excessive daytime sleepiness among patients with type 2 diabetes mellitus: a single-center study from Iran Khosro Sadeghniiat-Haghighi & Mohammad Reza Mohajeri-Tehrani & Ahmad Khajeh-Mehrizi & Farhad Fathi & Farzad Saremi-Rasouli & Mahsa Ghajarzadeh & Bagher Larijani
Received: 1 July 2013 / Accepted: 30 December 2014 # Research Society for Study of Diabetes in India 2015
Abstract Obstructive sleep apnea (OSA) and excessive daytime sleepiness (EDS) are common in patients with type 2 diabetes mellitus (T2DM). This study was aimed to evaluate the prevalence and risk factors of the OSA and EDS among Iranian patients with T2DM. We conducted a cross-sectional study on randomly selected 173 patients with T2DM aged 30 to 65. We assessed daytime sleepiness using the Epworth sleepiness scale and risk of OSA using the STOP-BANG questionnaire. Further information was demographic and anthropometric characteristics plus metabolic profile. Of all, 122 (74 %) patients were at high risk for OSA and 78 (45 %) patients suffered from EDS. Patients at high risk for OSA were older and had higher BMI, waist circumference, neck circumference, systolic, and diastolic blood pressure. In addition, men were significantly at a higher risk for OSA than women. Logistic regression revealed that age, male sex, and neck circumference were independent predictors of risk for OSA. The K. Sadeghniiat-Haghighi : A. Khajeh-Mehrizi (*) : F. Fathi Occupational Sleep Research Center, Tehran University of Medical Sciences, Tehran, Iran e-mail:
[email protected] K. Sadeghniiat-Haghighi Center for Research on Occupational Diseases, Tehran University of Medical Sciences, Tehran, Iran M. R. Mohajeri-Tehrani : B. Larijani Endocrinology and Metabolism Research Center, Tehran University of Medical Sciences, Tehran, Iran F. Saremi-Rasouli School of Nursing and Midwifery, Tehran University of Medical Sciences, Tehran, Iran M. Ghajarzadeh Brain and Spinal Injury Repair (BASIR) Research Center, Tehran University of Medical Sciences, Tehran, Iran
only independent predictor of EDS was age. Patients with T2DM are at high risk for OSA; also, daytime sleepiness is highly prevalent in this population. Our results indicated that the evaluation of OSA, EDS, and their risk factors should be included in the clinical management of patients with T2DM. Keywords Type 2 diabetes mellitus . Obstructive sleep apnea . Excessive daytime sleepiness . Iran
Introduction Obstructive sleep apnea (OSA) is a common treatable chronic sleep disorder which may affect up to 17 % of the middle-aged population [1]. It is characterized by frequent episodes of partial or complete obstruction of the upper airway during sleep, resulting in recurrent hypoxia, sleep fragmentation, and daytime symptoms including excessive daytime sleepiness (EDS), fatigue, morning headaches, impaired concentration and attention, dry mouth, personality changes, and depression [2]. It is related to substantial economic and health burdens which cost billions of dollars per year [3]. There has been recent realization about OSA’s affiliation with major complications including cardiovascular disorders, neurocognitive sequelae, and mood disorders [4]. Obesity is common among OSA patients. Moreover, adult obesity is associated with augmented incidence of type 2 diabetes mellitus (T2DM) [5]. Related metabolic disorders include impaired glucose tolerance, insulin resistance, dyslipidemia, central obesity, and hypertension; it has been taken into consideration that these metabolic conditions are associated with OSA and its complications [6]. It is predicted that the number
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of adults with diabetes will increase to 300 million in 2025 worldwide [7]. Cross-sectional studies have shown the high prevalence of OSA in patients with T2DM [8]. In a Japanese study, sleep apnea was detected among 75.5 % of hospitalized patients with T2DM [9]. The high prevalence of OSA in patients with T2DM reveals the importance of evaluation of the risk factors in the patients who suffer from it. In addition, diabetes mellitus is known to be the risk factor for EDS as an important component of sleep disorders in the general population [10]. It had been shown that the treatment of OSA with continuous positive airway pressure (CPAP) improves insulin resistance in the patients [11]. Studies on the relationship between T2DM and OSA and its accurate mechanism are yielded conflicting results. This study was aimed to evaluate the prevalence and risk factors of OSA and EDS in patients with T2DM referred to a diabetes clinic in Iran.
(Beckman Model Glucose Analyzer 2, brea, ca, USA) immediately after blood sampling. HbA1c levels were determined by a D-10 hemoglobin testing system (Bio-Rad Laboratories, Inc.). All other blood sample parameters were measured by enzymatic methods using a Hitachi 902 autoanalyzer (Hitachi, Tokyo, Japan). Low-density lipoprotein (LDL) was calculated as follows: TC–HDL–TG/5. Survey assessments The STOP-BANG questionnaire
Method
The STOP-BANG questionnaire consists of four yes/no questions evaluating snoring, tiredness, observed stop breathing during sleep, and high blood pressure plus four items about BMI, age, neck circumference, and gender. BMI more than 35 kg/m2, age more than 50 years, neck circumference more than 40 cm, and gender of male was considered as positive score. Patients with a score of 3 or more in STOP-BANG were identified to be high risk for OSA [13, 14].
Patients
The Epworth sleepiness scale
This cross-sectional study was carried out in the diabetes clinic of Shariati University Hospital in Tehran, Iran from March 2011 to September 2012. We consecutively recruited 173 patients with T2DM ranged between 30 to 65 years. T2DM was defined according to the recommendation of American Diabetes Association 2011 [12] and/or treatment of diabetes mellitus. Each patient signed an informed consent document after the study had been explained in detail. Patients with thyroid dysfunction, Cushing syndrome, steroid therapy as well as patients who did not want to participate in this study were excluded. The study was conducted with the approval of the Institutional Review Board of Diabetes Research Center, Tehran University of Medical Sciences, Iran.
In the Epworth sleepiness scale (ESS), patients rate the level of their sleepiness in 8 daily situations from 0 (would never doze) to 3 (high chance of dozing) [15]. The ESS total score can be obtained by summing item scores giving a total score ranging from 0 to 24. Patients with the ESS total score of equal or greater than 10 were considered to have excessive daytime sleepiness (EDS). Validity and reliability of the ESS had been assessed and approved in several studies, including the Iranian version [16].
Demographic, anthropometric, and laboratory data For each patient, age, gender, duration of diabetes, insulin therapy, or oral diabetes medications and exercise per week were obtained via questionnaire. Weight, height, waist circumference, hip circumference, neck circumference, systolic blood pressure (SBP), and diastolic blood pressure (DBP) were measured by technicians. Body mass index (BMI) was calculated as weight divided by the square of height. After a 12-h overnight fast, baseline blood samples were drawn to determine the fasting blood glucose (FBG), glycosylated hemoglobin (HbA1c), total cholesterol (TC), highdensity lipoprotein (HDL), and triglycerides (TG) from each patient. All the samples were sent to the laboratory of the diabetes clinic at Shariati University Hospital for analysis. FBG levels were determined by the glucose-oxidase method
Statistical analysis All measurements are expressed as mean ± standard deviation (SD). Normality of data was analyzed using the KolmogorovSmirnov test. Mann–Whitney U test was used for comparing continuous variables, and the χ2 test was used to assess differences in the sex and drug between high-risk and low-risk patients for OSA as well as between those with EDS and those not. Logistic regression analysis was performed to determine which variables predicted high risk for OSA and EDS. All P values were two-tailed, and P value greater than 0.05 was considered statistically significant. Predictive Analytics Software (PASW) version 18 was used for the statistical analysis.
Result The study enrolled 173 patients with T2DM. Twenty-seven patients (15.6 %) were treated with insulin, and others took
Int J Diabetes Dev Ctries
oral anti-diabetes agents. Table 1 lists the demographic, clinical characteristics, and biochemical characteristics of all participants. The mean STOP-BANG score was 3.4 (SD=1.4). STOPBANG revealed that 122 patients (74 %) were at high risk for OSA. Patients at high risk for OSA were older and had higher BMI, waist circumference, neck circumference, SBP, and DBP. In addition, men were significantly at higher risk for OSA than women (Table 2). The mean ESS score was 9.6 (SD=5.7). ESS showed that 78 patients (45 %) suffered from excessive daytime sleepiness (EDS). Patients with EDS were older and had higher SBP and DBP (Table 3). Logistic regression revealed that age, male sex, and neck circumference were independent predictors of risk for OSA and age was only independent predictor of EDS (Table 4).
Discussion In this study, using the STOP-BANG questionnaire, we showed that there was a high prevalence of patients at high risk for OSA; and using the Epworth sleepiness, we indicated that EDS was highly prevalent among Iranian patients with T2DM. Sleep performs like a metabolic regulator and sleep disorders, either effect quality or duration of sleep, harm the metabolism of substances such as carbohydrates [17]. Different studies focused on the association of OSA and diabetes mellitus (DM), revealed that OSA deteriorates the management of DM. On the other hand, OSA treatment improves
Table 2 Comparison of the patients according to the risk of OSA in STOP-BANG Characteristics
STOP-BANG
