730-P: Effects of Obstructive Sleep Apnea Treatment on Whole-Body and Adipose Tissue Insulin Sensitivity—Role of Senescence and Mitigation by Adjuvant Metformin Therapy

Introduction: Obstructive sleep apnea (OSA) is a prevalent sleep disorder linked to high type 2 diabetes risk. Positive airway pressure (PAP) therapy is the standard of care for OSA, but it inconsistently improves glucose homeostasis. Senescent cells are common in adipose tissue (AT) of patients with OSA and may impair insulin signaling. However, the effects of PAP therapy on AT senescence are not known. Addition of metformin, an insulin-sensitizer with anti-senescent effects, may be a good adjuvant therapeutic strategy to improve glycemic control in patients with OSA. Methods: We randomly assigned 16 nondiabetic participants with OSA (Mean± SD; age: 50.9 ± 6.7 y, BMI: 36.5 ± 2.9 kg/m2) in a 1:1 ratio to receive either 2g metformin or placebo daily along with PAP therapy for 3 months in a double-blind pilot study. Whole body and AT insulin sensitivity was determined by 2h oral glucose tolerance test (OGTT). AT biopsy was obtained to estimate tissue insulin signaling and senescence. Results: The metformin and placebo groups had comparable age, BMI and OSA severity at baseline. PAP compliance was 38% and 75% in the metformin and placebo groups, respectively. Matsuda Index, glucose area under the curve (2h AUC), and free-fatty acid suppression at baseline and follow-up were not different in metformin or placebo treated groups. Compared to baseline, insulin AUC and insulin to glucose AUC ratio during OGTT was unchanged in the metformin but increased in the placebo group. Metformin, but not placebo, was associated with increased insulin mediated AKT phosphorylation and decreased senescence biomarkers (p21 and MCP1) in AT during the follow-up visit. Conclusion: Metformin, as adjunct to PAP therapy, attenuated insulin rises during OGTT, improved AT insulin signaling, and lowered senescence biomarkers in OSA patients. Larger trials of longer treatment duration are needed to determine if metformin can prevent diabetes in OSA patients.