Hypertension, metabolic syndrome, prediabetes, and diabetes associated with obstructive sleep apnea syndrome

Associations between hypertension, metabolic syndrome, prediabetes, diabetes, and obstructive sleep apnea syndrome (OSAS) were assessed in a prospective single center clinical study including patients from an outpatient sleep clinic and an inpatient sleep lab.

The Görlitz Metabolic Study is a prospective trial assessing the relationship between current definitions of the metabolic syndrome (Adult Treatment Pannel III, ATP 3; International Diabetes Federation, IDF; metabolic vascular syndrome, MVS), its constituting parameters, and OSAS in different patient cohorts in Upper Lusatia, Germany. In addition, the diagnostic relevance of a newly developed scoring system, the Carolus Sleep Score (CSS), was compared to the Epworth Sleepiness Scale (ESS). A total of 2,362 patients were consecutively included in the study. The statistics were done exploratively.

Outpatients with OSAS who had not yet been treated had a mean blood pressure of 157/94 mmHg with a hypertension prevalence of 71%, while the mean blood pressure of those already treated was 153/89 mmHg with a hypertension prevalence of 68%. In 42% of the obstructive sleep apnea (OSA) and in 27% of the non-OSA patients, the criteria of all three definitions of the metabolic syndrome were fulfilled. The coefficients of correlation were 0.22 for the respiratory disturbance index (RDI) vs. body mass index (BMI), 0.26 for RDI vs. abdominal circumference, 0.19 for CPAP vs. BMI, and 0.25 for CPAP vs. abdominal circumference. There was a diabetes prevalence of 27% in the OSA patients and 16% in the non-OSA patients. In addition, when evaluating a subgroup of OSA patients with the same mean abdominal circumference as the non-OSA patients, the prevalences of hypertension, metabolic syndrome, and diabetes were still higher in those who suffered from OSA. The CSS clearly proved to be more suitable for primary OSA screening than the ESS. In addition, the CSS correlated considerably better with the RDI (r=0.36) than the ESS (r=0.21).

Despite the uncontrolled real-life clinical setting, the previously reported relevance of OSA for cardiovascular and metabolic disturbances was clearly verified. The data unequivocally show that the recommendations in the different hypertension and diabetes guidelines to look for hypertension and diabetes, respectively, in OSA patients and vice versa for OSAS in hypertensive and diabetic patients should be regarded seriously. The CSS seems to be superior for screening patients compared to the ESS.