GLYCOSA Study:Effect of PAP Treatment on Glycemic Control in Patients With Type 2 Diabetes

Obstructive Sleep Apnea (OSA) and type 2 diabetes mellitus are two prevalent medical conditions with significant associated cardiovascular and cerebrovascular morbidity and mortality. Research indicates that the prevalence of OSA is increased in diabetic patients when compared with normoglycemic patients and that OSA is independently associated with type 2 diabetes. Further research suggests that effective treatment of the OSA with continuous positive airway pressure (CPAP) improves insulin responsiveness in both non-diabetic OSA patients and diabetic-OSA patients. We are proposing a clinical trial to evaluate the impact of 6 months of CPAP therapy on glycemic control in type 2 diabetic patients with OSA.

The primary objective of this study is to assess the effectiveness of CPAP in improving glycemic control (HbA1c) in type 2 diabetic patients with newly diagnosed OSA. Secondary objectives of this study include: assessment of fasting and post prandial glucose, determination as to whether there are any biochemical markers for OSA in the type 2 diabetic population; assessment of any improvements in cardiovascular outcomes; evaluation of any improvement in quality of life. Patients with OSA will be randomized into one of two groups: either a CPAP treatment group or a non-treatment group. Patients will be followed at 3 months and 6 months with collection of various lab tests to assess glycemic control.

Patients attending clinical sites involved with the trial will be asked to participate in the study. Patients will undergo a sleep test and if positive for Obstructive Sleep Apnea (OSA) will continue in the study.

At the time of enrolment baseline history and physical examination will be assessed. Baseline lab samples will also be obtained to measure levels of fasting blood glucose, insulin, HbA1c, lipids, biochemical markers and creatinine/albumin ratio. Post-prandial glucose levels and 24-hour ambulatory blood pressure will be evaluated. Participants will also be asked to complete Quality of Life (QoL) questionnaires.

Participants will be randomised into either continuous positive airway pressure CPAP treatment or no treatment. All subjects will be counselled regarding adopting a healthy lifestyle and advised on the Heart Foundation, National Health and Medical Research Council, and American Diabetes Association nutrition and exercise recommendations. Follow-up on adoption of the healthy lifestyle approach will be done for all study participants for the duration of the trial period. Total duration of a patient's participation is 6 months.

Eligibility Criteria:
Inclusion Criteria:

1. 18 years of age or older,
2. Known diagnosis of type 2 diabetes for at least 3 months
3. HbA1c \>6.5% and \</= 8.5%
4. BMI \</= 40 kg/m2

Exclusion Criteria:

1. Requires oxygen therapy
2. OSA is severe (AHI\>70 or SaO2\<70%)
3. Work in transport related industries
4. Previous diagnosis of OSA
5. Known MVA due to sleepiness in the previous 5 years
6. Insulin-requiring
7. Use of GLP-1 mimetic (e.g. Byetta) for \< 6 months or \> 6 months but weight not stable
8. Unstable angina