Background
Low baroreflex sensitivity is an indicator of early cardiovascular autonomic neuropathy. We explored the association between baroreflex sensivity and blood oxygen saturation (SpO2) in type 1 diabetes and various degrees of microvascular disease.

Methods
In this Danish-Finnish cross-sectional multicentre study, baroreflex sensivity and SpO2 (pulse oximetry) were examined in persons with type 1 diabetes and normoalbuminuria (n = 98), microalbuminuria (n = 28), or macroalbuminuria (n = 43), and in non-diabetic controls (n = 54). Associations and differences between groups were analysed using regression models and adjustment included age, sex, smoking, HbA1c, blood haemoglobin, urine albumin creatinine ratio, body mass index, and estimated glomerular filtration rate.

Results
In type 1 diabetes, higher baroreflex sensitivity was associated with higher SpO2 before adjustment (% increase per one % increase in SpO2 = 20 % (95%CI: 11–30); p < 0.001) and the association remained significant after adjustment (p = 0.02). Baroreflex sensitivity was not different between non-diabetic controls and persons with type 1 diabetes and normoalbuminuria (p = 0.052). Compared with type 1 diabetes and normoalbuminuria, baroreflex sensitivity was lower in micro- (p < 0.001) and macroalbuminuria (p < 0.001). SpO2 was lower in persons with type 1 diabetes and normoalbuminuria compared with non-diabetic controls (p < 0.01). Within the participants with type 1 diabetes, SpO2 was not different in micro- or macroalbuminuria compared with normoalbuminuria (p-values > 0.05), but lower in macro-compared with microalbuminuria (p < 0.01).

Conclusions
Lower baroreflex sensitivity was associated with lower SpO2 in type 1 diabetes. The present study support the hypothesis that hypoxia could be a therapeutic target in persons with type 1 diabetes.