In Most With OSA and Diabetes, PAP Therapy Does Not Improve Glycemic Control

In patients with type 2 diabetes and moderate-to-severe obstructive sleep apnea (OSA), glycemic control or variability was not improved by positive airway pressure (PAP) therapy, according to study findings published in CHEST.

Increased risk for cardiovascular disease in patients with type 2 diabetes has been associated with glycemic variability independent of glycosylated hemoglobin (HbA1c) levels. The effect of OSA PAP therapy on HbA1c is uncertain. Researchers therefore sought to investigate whether glycemic variability was improved in patients with type 2 diabetes and moderate-to-severe OSA with the use of PAP therapy. Change in the standard deviation (SD) on continuous glucose monitoring (CGM) from baseline to 3 months was the primary outcome. Changes in CGM-derived average glucose, pre- and post-meal glucose, bedtime glucose, and HbA1c levels were secondary outcomes.

This open label, single-center, controlled trial (ClinicalTrials.gov Identifier: NCT02454153) conducted from December 2014 to December 2019 included 184 adult patients (aged 21 to 75 years) from the Baltimore-Washington DC area with type 2 diabetes and moderate-to-severe OSA who were randomly assigned to receive either PAP therapy with lifestyle counseling (n=92 intervention) or lifestyle counseling alone (n=92 control). Participants (mean [SD]age, 59.6 [9.1] years; 49.0% female) received lifestyle counseling information on exercise, nutrition, and good sleep hygiene practices.

The PAP device was set to the 95^th percentile of pressure for eliminating airflow limitation, hypopneas, and apneas. Average PAP therapy use was 5.4 (1.6) hours/night. Notably, glucose lowering medications used by study participants in both groups did not change over the 3-month study period.

Age, race, body mass index, and HbA1c were comparable between intervention and control groups, as was statin and oral hypoglycemic use. Severity of OSA was comparable between groups; however, 11% of the control group vs 1% of the intervention group had prevalent cardiovascular disease. Overall, 11 of the participants were lost to follow-up. Additionally, baseline CGM measurements were carried forward to the 3-month visit for 9 participants missing follow-up CGM data. PAP adherence (at least 4 hours/night for at least 70% of the nights) was 77%.

The researchers found no differences in any outcomes, primary or secondary, in either group. There were no differences in the amounts of daily fat, protein, or carbohydrates or daily average calories consumed in either group.

Notably, among women studied, PAP therapy was associated with improvement in the SD of glucose levels (mean difference of change between intervention and control groups, 3.5 mg/dL; P = .02) in exploratory analyses. In the intervention group, mean glucose decreased by 0.5 mg/dL for women but increased by 14.0 mg/dL in the control group. Additionally, these analyses showed PAP therapy in women was associated with lower bedtime glucose levels (34.6 mg/dL; P <.01) and lower post-dinner glucose levels (20.1 mg/dL; P <.01). However, there were no significant changes in any of the self-monitoring of blood glucose levels in men.

Study limitations include the single-center design and the narrow population of PAP adherent patients.

“The results of this randomized clinical trial demonstrate that PAP therapy for moderate to severe OSA does not improve glycemic variability as assessed by continuous glucose monitoring in patients with type 2 diabetes,” the study authors concluded. However, they noted that PAP therapy may improve glucose variability in women, not men, as suggested by exploratory analyses, and that “Post-dinner and bedtime glucose levels were higher in those that did not receive PAP therapy.”

This article originally appeared on Pulmonology Advisor