Type 2 diabetes and pre-diabetes are associated with obstructive sleep apnea in extremely obese subjects: a cross-sectional study

Abstract

Background: Obstructive sleep apnea (OSA) is a common yet underdiagnosed condition. The aim of our study is to test whether prediabetes and type 2 diabetes are associated with obstructive sleep apnea (OSA) in extremely obese (BMI ≥ 40 kg/m²) subjects.

Methods: One hundred and thirty seven consecutive extremely obese patients (99 females) from a controlled clinical trial [MOBIL-study (Morbid Obesity treatment, Bariatric surgery versus Intensive Lifestyle intervention Study) (ClinicalTrials.gov number NCT00273104)] underwent somnography with Embletta® and a 2-hour oral glucose tolerance test (OGTT). OSA was defined by an apnea-hypopnea index (AHI) ≥ 5 events/hour. Patients were categorized into three groups according to criteria from the American Diabetes Association: normal glucose tolerance, pre-diabetes and type 2 diabetes. Multiple logistic regression analysis was used to identify possible determinants of OSA.

Results: The patients had a mean (SD) age of 43 (11) years and a body mass index (BMI) of 46.9 (5.7) kg/m². Males had significantly higher AHI than females, 29 (25) vs 12 (17) events/hour, p < 0.001. OSA was observed in 81% of men and in 55% of women, p = 0.008. Twenty-nine percent of subjects had normal glucose tolerance, 42% had pre-diabetes and 29% had type 2 diabetes. Among the patients with normal glucose tolerance 33% had OSA, while 67% of the pre-diabetic patients and 78% of the type 2 diabetic patients had OSA, p < 0.001. After adjusting for age, gender, BMI, high sensitive CRP and HOMA-IR, both pre-diabetes and type 2 diabetes were still associated with OSA, odds ratios 3.18 (95% CI 1.00, 10.07), p = 0.049 and 4.17 (1.09, 15.88), p = 0.036, respectively. Mean serum leptin was significantly lower in the OSA than in the non-OSA group, while other measures of inflammation did not differ significantly between groups.

Conclusions: Type 2 diabetes and pre-diabetes are associated with OSA in extremely obese subjects.

Trial registration: MOBIL-study (Morbid Obesity treatment, Bariatric surgery versus Intensive Lifestyle intervention Study) (ClinicalTrials.gov number NCT00273104).

Figure 1

Flow chart of 181 patients screened for participation in the MOBIL-study. Initially three patients were excluded due to a BMI < 35 kg/m² and nine due to failed sleep registrations. Twenty nine of these patients had a BMI < 40 kg/m² and three had a missing OGTT, thereby leaving 137 extremely obese patients for inclusion in the present analysis.

Figure 2

Categories of morbidly obese subjects according to various levels of the apnea-hypopnea index (AHI). Dotted bars represent patients without OSA (AHI < 5 events/hour). Mild OSA is defined as AHI 5 - 15 events/hour, moderate OSA as 15 - 30 events/hour and severe OSA as > 30 events/hour.

Figure 3

Prevalence of OSA in 137 extremely obese subjects (101 females) according to various categories of glucose tolerance.

Figure 4

Prevalence of OSA in 137 extremely obese subjects (101 females) according to various categories of glucose tolerance. Females are subgrouped according to menopausal status. The mean (SD) ages of men, premenopausal- and postmenopausal women were 44 (11), 38 (8) and 57 (7) years, respectively.