Effect of Metformin on Sleep Architecture in Patients with Comorbid Diabetes and Sleep Apnea

Background/Objectives: Patients with poor sleep are at high risk of developing type II diabetes mellitus (T2DM). Since T2DM is linked to increased risk of obstructive sleep apnea (OSA), and Metformin is commonly used to treat T2DM, we examined how Metformin affects sleep stages in patients with concurrent T2DM and OSA-related symptoms of snoring and fatigue. Patients with T2DM on Metformin progressively develop increased insulin resistance associated with sleep disturbances and poor glycemic control. We therefore explored sleep pattern changes in patients with OSA symptoms and T2DM on Metformin, with a special focus on whether Metformin affects sleep architecture. Methods: Polysomnogram (PSG) data from patients with T2DM on Metformin was evaluated along with data on age, body-mass index (BMI), and biological sex. Data analysis included mean ± standard deviation, t-test with p < 0.05 taken as significant, and linear regression. Results: Patients with a BMI of less than 30 (non-obese) and taking Metformin exhibited a significantly shorter rapid eye movement sleep stage (REM) duration than patients on alternative therapies (p = 0.036). No such difference in REM was found for patients with a BMI of 30 or greater (obese) taking Metformin. While there was also no significant difference in slow-wave sleep stage (N3) duration with Metformin use, linear regression identified a moderate negative correlation between N3 and age in patients taking non-Metformin therapies (R2 = 0.4555). No significant correlations between sleep stage duration and patient sex, smoking status, or BMI greater than 30 were identified. Conclusions: Overall, patients with OSA and T2DM on Metformin had lower mean quantities of N3, and REM sleep compared to those not on Metformin. Non-obese patients with T2DM and OSA being treated with Metformin were observed to have less REM sleep, regardless of sex or smoking history. N3 and REM sleep are needed for the timely secretion of growth hormone and memory consolidation. Since Metformin is correlated with differences in N3 and REM sleep, it may contribute to the development of insulin resistance. Future studies are needed to explore potential causes for this relationship and how it may affect the treatment of T2DM.