Association between Self-Reported Habitual Snoring and Diabetes Mellitus: A Systemic Review and Meta-Analysis

Table 1

Characteristics of included studies in this meta-analysis.

(a)

First author; Year	Country	Source and study type	Sample size	Female (%)	Age range	OR or RR (95% CI)	Adjusted variables
Sabanayagam; 2012 [17]	America	Population-based; Cross-sectional	6522	48.8	20–85	1.44 (1.16–1.79)	Age, sex, ethnicity, education, smoking, alcohol, physical activity, BMI, depression, SBP, CRP, and TC
Valham; 2009 [18]	Sweden	Population-based; Cross-sectional	7905	51.2	25–79	Female: 1.58 (1.02–2.44); Male: 0.92 (0.64–1.33)	Smoking, age, BMI, and waist circumference
Renko; 2005 [19]	Finland	Population-based; Cross-sectional	593	58.7	61–63	1.93 (1.04–3.57)	Age, weight gain, smoking, alcohol dependence, and physical inactivity
Marchesini; 2004 [20]	Italy	Population-based; Cross-sectional	1890	78	20–65	1.31 (0.95–1.81); Female: 1.62 (1.11–2.36); Male: 0.81 (0.45–1.50)	Age, sex, and BMI
Lindberg; 2007 [21]	Sweden	Population-based; Cross-sectional	6779	100%	20–99	No EDS: 1.36 (0.87–2.13); EDS: 1.82 (0.97–3.43)	Age, BMI, smoking, physical activity, and alcohol dependency
Enright; 1996 [22]	America	Population-based; Cross-sectional	5201	57%	≥65	Women: 1.34 (0.10–1.65)	Age and being married
Al-Delaimy; 2002 [23]	America	Population-based; Prospective cohort	69852	100%	40–65	1.63 (1.29–2.07)	Age, high TC, high BP, smoking, BMI, physical activity, alcohol use, postmenopausal hormone use, family history of diabetes, sleeping position, sleep time, years of shift-work, and WHR
Elmasry; 2000 [1]	Sweden	Population-based; Prospective cohort	2504	0%	30–69	Nonobese: 1.06 (0.36–3.1); Obese: 7.0 (2.9–16.9)	Age, weight gain, smoking, alcohol dependence, and physical inactivity

(b)

Definition of snoring	Assessment/definition of DM	Presence of comorbidities	NOS score
Questionnaire answer: never or rare, occasionally as nonhabitual snorers; frequently as habitual snorers	Serum glucose ≥ 126 mg/dL after fasting for a minimum of 8 hours, a plasma glucose ≥ 200 mg/dL for those who fasted <8 hours or HbA1c ≥ 6.5%, a self-reported DM or current use of oral hypoglycemic medication or insulin	(—)	7
Questionnaire answer: always or often as habitual snorers; sometimes, never, or almost never as nonhabitual snorers	Questionnaire answer: ‘‘Do you suffer from DM?”	(—)	8
Questionnaire answer: those who reported snoring every or almost every night were classified as habitual snorers	Previously diagnosed DM, OGTT according to WHO criteria in 1998	(—)	7
Questionnaire answer: occasional or habitual as habitual snorers	Previously diagnosed DM, OGTT according to WHO criteria in 1998	Hypertension, hyperlipidemia	7
Questionnaire answer: how often they snored using a five-point scale; snoring was defined as a score of 3–5	Questionnaire answer: ‘‘Do you have diabetes?’’ and/or attended regular medical examinations for diabetes	Hypertension	7
Questionnaire answer: yes or no or don’t know; yes as habitual snorers	History of DM, current use of insulin or oral hypoglycemic medication, fasting glucose ≥ 140 mg/dL, or 2-hour postload glucose ≥ 200 mg/dL.	Hypertension, carotid disease, and arthritis	7
Questionnaire answer: regularly as habitual snorers; occasionally or never	Classic symptoms associated with an elevated plasma glucose level or no symptoms, but at least two elevated plasma glucose values on different occasions; or treatment with hypoglycemic medication	(—)	8
Questionnaire answer: a five-point scale: ≥4 was defined as habitual snorers; ≦3 was defined as nonhabitual snorers	Questionnaire: self-report DM or confirmed by medical records	(—)	8

OR, odds ratio; RR, risk ratio; BMI, body mass index; SBP, systolic blood pressure; CRP, C reactive protein; TC, cholesterol; BP, blood pressure; DM, diabetes mellitus; HbA1c, glycosylated hemoglobin; OGTT, oral glucose tolerance test; WHO, World Health Organization; NOS: Newcastle-Ottawa scale. Note: a means studies report OR, while b means study reports RR.