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Benefits of vitamin D in patients with type 2 diabetes remain unverified
Evidence for beneficial effects of vitamin D supplementation on hyperglycemia, beta cell secretion or insulin sensitivity in patients with type 2 diabetes is lacking, according to findings published in the Journal of Diabetes & Metabolic Disorders.
In a review of 17 randomized controlled trials and seven longitudinal studies, Nisha Nigil Haroon, MD, PhD, DM, and colleagues from other institutions found no real support for claims of improvements with supplements and called for more investigation.
“The pathogenetic and therapeutic role of vitamin D in glucose metabolism is still unclear,” the researchers wrote. “Experimental studies as well as large scale randomized controlled trials with good study design, optimal vitamin D supplementation and long-term follow up are needed on this topic.”
The investigators identified the trials, all with a minimum follow-up of one month, through a keyword search in Medline and PubMed.
Vitamin D supplementation appeared to positively affect glycemic control and metabolic parameters, including insulin resistance and beta cell dysfunction, in short-term studies, following patients for up to 3 months; however, low methodological quality rendered the evidence weak.
In long-term studies, following patients for more than 3 months, no significant effect was observed on HbA1c, beta cell function or insulin resistance; the methodologies, inclusion criteria, modes of vitamin D supplementation and follow-up period of the studies varied.
“Our systematic review underscores the need for future studies given that both vitamin D deficiency and diabetes are conditions with huge public health concern worldwide,” the researchers wrote. – by Allegra Tiver
Disclosure: The researchers report no relevant financial disclosures.