Type 2 Diabetes Caused by Low Vitamin D Disputed

Associations of SNPs with risk of type 2 diabetes were based on 28,144 cases of type 2 diabetes and 76,344 non-cases from a case-cohort study. Apart from a few studies, all studies ascertained type 2 diabetes cases through biochemical testing, such as concentrations of fasting glucose, two-hour glucose, or HbA1c.

SNPs were assayed by the Illumina 660 quad-chip or the Metabochip (Illumina; Little Chesterford, UK). The assays used 10 ng of genomic DNA in a 2.5 μL reaction volume, 384-well plate with a G-Storm GS4 Thermal Cycler (Genetic Research Instrumentation (GRI); Rayne, UK). Endpoint detection and allele calling were done with an ABI PRISM 7900HT Sequence Detection System (Applied Biosystems; Paisley, UK). The authors also used circulating 25(OH)D levels, considered the best indicator of vitamin D status, as the measure for vitamin D. Insufficiency was defined as having blood levels of 25(OH)D under 50 nmol/L.

The scientists found no evidence of a link between the risk of developing type 2 diabetes and the different gene variants that control blood levels of vitamin D. They also found no links between varying levels of vitamin D and several features of type 2 diabetes, such as glucose and glycated hemoglobin, and neither did they find evidence that low vitamin D causes the disease. The authors concluded that their findings suggest that interventions to reduce the risk of type 2 diabetes by increasing concentrations of 25(OH)D are not currently justified. The study was published on October 1, 2014, in the journal the Lancet Diabetes & Endocrinology.

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