Obstructive Sleep Apnea and Diabetic Microvascular Complications

Microvascular complications (neuropathy, nephropathy, and retinopathy) are very common in patients with type 2 diabetes (T2D) and contribute significantly to the morbidity and mortality of this condition. Hence, preventing the development or slowing the progression of these complications is a major aim of treatment in patients with T2D. However, despite the beneficial impact of intensive metabolic control, these complications remain very common. Obstructive sleep apnea (OSA) and T2D share a major risk factor, which is obesity; therefore, it is not surprising that these two conditions often co-exist. OSA and hyperglycemia share common molecular consequences, such as increased oxidative and nitrosative stress, protein kinase C activation, increased advance glycation end-product, and increased inflammation-all of which can result in vascular disease. Hence, it is plausible that OSA might contribute to the development and progression of microvascular complications in patients with T2D. Several cross-sectional studies have shown that diabetic nephropathy, neuropathy, and sight-threatening retinopathy are more common in patients with T2D and OSA than T2D only. More importantly, early longitudinal studies are suggestive that OSA results in the development of nephropathy and retinopathy in patients with T2D and that continuous positive airway pressure treatment might slow the development and progression of these complications. This area of research is still in its infancy, so more longitudinal and interventional studies are needed to determine the role of OSA and the impact of its treatment on the development and progression of microvascular complications in patients with T2D. Interestingly, early data from cross-sectional studies in patients with type 1 diabetes suggest a similar relationship between OSA and microvascular complications as that observed in patients with T2D.