Does serum vitamin-D predict insulin resistance in individuals with prediabetes?

Sir,

Apropos of article on the association between serum vitamin-D and insulin resistance in individuals with prediabetes1, the authors need to be complimented for their effort in establishing vitamin-D deficiency as a predictor for insulin resistance. As pointed out by the authors the study showed that vitamin-D insufficiency/deficiency was common among individuals with prediabetes. However, there are some basic concerns with this finding. To establish this statement, the study should have reflected on the fact that this condition (vitamin-D deficiency in this case) is common in one population (pre-diabetics in this case) in comparison to some other population or the general population. Given the fact that vitamin-D deficiency is being widely reported not just from India but across the other populations of the world, we need to re-look at this statement. Studies estimate that 1 billion people worldwide have vitamin-D deficiency or insufficiency2. There is widespread prevalence of varying degrees (50-90%) of vitamin-D deficiency with low dietary calcium intake in Indian population3. Now, the prediabetes group included in this study1 has been selected automatically from this vitamin-D deficient population. Therefore, the fact that this study reporting on vitamin-D deficiency/insufficiency in 73.25 per cent individuals with prediabetes may just be a reflection of deficiency prevalent in general population and not specific to prediabetics.