Nocturnal autonomic dysfunction associated with obstructive sleep apnea in type 1 diabetes
Aims: This single-center, cross-sectional study aimed to investigate whether moderate-to-severe obstructive sleep apnea (OSA) is associated with impaired autonomic nervous system function in adults with type 1 diabetes (T1D). Specifically, the authors examined whether OSA severity is associated with differences in diurnal and nocturnal markers of cardiovascular autonomic regulation.
Methods: Adults with type 1 diabetes (aged 18–60 years, disease duration ≥5 years) underwent polysomnography and were stratified into two groups based on apnea–hypopnea index (AHI <15 vs ≥15 events/h). Autonomic assessment included heart rate variability (HRV) analysis during wakefulness and sleep, cardiovascular autonomic reflex tests (CARTs), Sudoscan® and urinary catecholamine measurement.
Results: Patients with moderate-to-severe OSA (AHI ≥15/h, n=6) showed reduced parasympathetic modulation during REM sleep compared with those with AHI <15/h (n=14), reflected by lower HFnu (p=0.045) and higher REM heart rate (p=0.036), together with an increased urinary norepinephrine/epinephrine ratio (p=0.03), suggesting enhanced sympathetic activation.
Confirmed CAN was observed in 3 of 6 patients with AHI ≥15/h and in 2 of 14 patients with AHI <15/h. No significant differences were observed in the prevalence of CAN, daytime HRV parameters, CARTs or sudomotor function between groups. Furthermore, AHI was positively correlated with orthostatic systolic blood pressure changes (r=0.58; p=0.01), suggesting a potential association between OSA severity and autonomic regulation.
Conclusions: The findings suggest that OSA in T1D is primarily associated with subtle nocturnal autonomic disturbances, particularly during REM sleep, rather than with overt cardiovascular autonomic neuropathy. These observations support the hypothesis that sleep-disordered breathing may contribute to nocturnal autonomic imbalance in T1D.
Comments: The study addresses an important and relatively underexplored aspect of type 1 diabetes by investigating the relationship between OSA and autonomic function. The multimodal approach, integrating polysomnography with physiological and biochemical markers of autonomic regulation, provides a comprehensive evaluation of potential OSA-related autonomic alterations, particularly during REM sleep.
However, several limitations should be considered when interpreting the findings. First, the study included a relatively small sample size, which may have limited the statistical power to detect differences in some autonomic parameters. Second, the presence of confirmed CAN in 3 of 6 patients with moderate-to-severe OSA represents a potential confounding factor and makes it difficult to determine the temporal relationship between OSA and autonomic dysfunction. Specifically, it remains unclear whether OSA contributes to autonomic impairment or whether pre-existing autonomic dysfunction may influence susceptibility to sleep-disordered breathing. Third, the interpretation of CARTs should be approached with caution, as fixed reference thresholds were applied for normative values. Finally, the inclusion of the sustained handgrip test in the assessment battery should be acknowledged, as this manoeuvre is less commonly incorporated into contemporary standardized protocols for CAN evaluation. Thus, while highlighting the relevance of OSA on autonomic function, these findings should be considered hypothesis-generating and warrant confirmation in larger, prospective studies with longitudinal follow-up.
Simona Zaccaria
Reference. Faivre M, Gouzi F, Ayoub B, Myzia J, Villard O, Suc A, Hayot M, Roubille F, Dauvilliers Y, Thireau J, Bughin F. Deleterious impact of obstructive sleep apnea on autonomic nervous system control during rapid-eye-movement sleep in adult type 1 diabetes. Physiol Rep. 2026 Jun;14(12):e70951. doi: 10.14814/phy2.70951. PMID: 42304818; PMCID: PMC13273019.
