Are vitamin D and B deficiency relevant to the pathogenesis and treatment of diabetic neuropathy?

An update on vitamin D and B deficiency in the pathogenesis and treatment of diabetic neuropathy: a narrative review

Diabetic peripheral neuropathy (DPN) is highly prevalent and affects up to 50% of patients with diabetes. Painful neuropathic symptoms may occur in a third of patients with diabetes and is a major cause of sleep disturbance, morbidity and poor quality of life. Effective treatment of DPN remains a major challenge as current therapeutic options have a number of undesirable side effects and only provide a partial response to neuropathic pain. Furthermore, there are a lack of treatments that modulate the natural history of DPN. A growing body of evidence suggests that vitamin B and vitamin D may have analgesic effects and neuroprotective benefits in DPN. This narrative review explores the role of these vitamins in DPN. Given their limited side effects, further mechanistic studies and good quality randomized controlled trials of their putative analgesic ability are required to define the role of vitamin B and D in DPN.

Vitamin D and Diabetic Complications: True or False Prophet?

Vitamin D deficiency is now recognized as a condition of increasing prevalence worldwide. Vitamin D has an established role in calcium and bone metabolism; however, more recently associations with vitamin D deficiency and risk of developing diabetes, diabetes complications, and cardiovascular disease have all been acknowledged. The vitamin D receptor is ubiquitously expressed, and experimental, in vitro, and in vivo studies strongly suggest a role in regulating the transcription of multiple genes beyond calcium homeostasis. These include antiproliferative, immunomodulatory, angiogenic, inhibition of the renin-angiotensin-aldosterone system, and neurotrophic factor expression. Observational studies report a strong association between vitamin D deficiency and cardiovascular and metabolic disorders; however, there remains a paucity of large long-term randomized clinical trials showing a benefit with treatment. An increasing body of literature suggests a possible pathogenetic role of vitamin D in the long-term complications of diabetes and vitamin D deficiency may also exacerbate symptoms of painful diabetic peripheral neuropathy. It remains unknown if supplementation of vitamin D to normal or non-deficient levels alters pathogenetic processes related to diabetic microvascular complications. With the high prevalence of vitamin D deficiency in patients with diabetes and putative mechanisms linking vitamin D deficiency to diabetic complications, there is a compelling argument for undertaking large well-designed randomized controlled trials of vitamin D supplementation.