Nocturnal intermittent hypoxia and the development of type 2 diabetes: the Circulatory Risk in Communities Study (CIRCS)

Although the associations between obstructive sleep apnoea and type 2 diabetes mellitus have been reported in cross-sectional design studies, findings on the prospective association between the two conditions are limited. We examined prospectively the association between nocturnal intermittent hypoxia as a surrogate marker of obstructive sleep apnoea and risk of type 2 diabetes. A total of 4,398 community residents aged 40 to 69 years who had participated in sleep investigation studies between 2001 and 2005 were enrolled. Nocturnal intermittent hypoxia was assessed by pulse-oximetry and defined by the number of oxygen desaturation measurements a parts per thousand currency sign3% per h, with five to < 15 per h corresponding to mild and 15 events or more per h corresponding to moderate-to-severe nocturnal intermittent hypoxia, respectively. The development of type 2 diabetes was defined by: (1) fasting serum glucose a parts per thousand yen7.00 mmol/l (126 mg/dl); (2) non-fasting serum glucose a parts per thousand yen11.1 mmol/l (200 mg/dl); and/or (3) initiation of glucose-lowering medication or insulin therapy. Multivariable model accounted for age, sex, BMI, smoking status, current alcohol intake, community, borderline type 2 diabetes, habitual snoring, excessive daytime sleepiness, sleep duration and (for women) menopausal status. By the end of 2007, 92.2% of participants had been followed up (median follow-up duration [interquartile range] 3.0 [2.9-4.0] years) and 210 persons identified as having developed diabetes. The multivariable-adjusted hazard ratio (95% CI) for developing type 2 diabetes was 1.26 (0.91-1.76) among those with mild nocturnal intermittent hypoxia and 1.69 (1.04-2.76) among those with moderate-to-severe nocturnal intermittent hypoxia (p = 0.03 for trend). Nocturnal intermittent hypoxia was associated with increased risk of developing type 2 diabetes among middle-aged Japanese.