The relationship between obstructive sleep apnea and insulin resistance in patients with type 2 diabetes mellitus: a cross-sectional observational study.

BACKGROUND

Increasing evidence suggests obstructive sleep apnea (OSA) is an independent risk factor for type 2 diabetes. Insulin resistance is the primary mechanism in the early stage of type 2 diabetes. The aim of this study was to assess the prevalence of OSA among patients with type 2 diabetes mellitus and to examine the association between OSA severity and insulin resistance.

METHODS

This study adopted a cross-sectional observational design. We enrolled patients hospitalized for poorly controlled type 2 diabetes mellitus from the Endocrine Department of Beijing Chao-Yang Hospital and recorded their demographic and clinical data in an electronic case report form. Polysomnography (PSG) monitoring was performed for all the subjects. According to the apnea hypopnea index (AHI), the subjects were classified into the following three groups: the control group, AHI <5 events per hour; the mild-OSA group, 5 events per hour ≤ AHI <15 events per hour; and the moderate-to-severe-OSA group, AHI ≥15 events per hour.

RESULTS

A total of 96 patients with type 2 diabetes were enrolled in this study, among whom 78 (81.28%) were diagnosed with OSA. The participants were categorized into three groups: a control group of 18 patients without OSA, a mild-OSA group of 54 patients, and a moderate-to-severe OSA group of 24 patients. Analysis revealed that the C-peptide area under the curve (AUCcp) was significantly greater in the moderate-to-severe OSA group compared to the control group. Additionally, the homeostasis model assessment of insulin resistance (HOMA-IR) was significantly higher in both the moderate-to-severe OSA and mild OSA groups relative to the control group. Multiple stepwise regression analysis revealed that the AHI and AUCcp were positively correlated (r=0.323, P=0.001). Both the AHI and body mass index (BMI) were positively correlated with the HOMA-IR index (P=0.007 and 0.02, respectively).

CONCLUSIONS

A high prevalence of OSA was observed among patients hospitalized for poorly controlled type 2 diabetes; further, its severity was positively correlated with insulin resistance.