|Without sun exposure even a D-rich diet won't contain enough vitamin D (photo from WebMD Slideshow)|
Next to the often-heard claim that the corresponding studies simply weren't using enough vitamin D3, another, actually more reasonable hypothesis why the trials fail is that the provision of a substance that may protect you from developing type II diabetes when you've already messed yourself up is nonsensical.
Against that background studies like the one researchers from the Sher-I-Kashmir Institute of Medical Sciences in Kashmir conducted recently are particularly interesting, because in contrast to the subects in the average US study, Kushay's et al.'s subjects were 137 men and women that were diagnosed as with "prediabetes". All of them had to make standard lifestyle changes, but only 68 received 60,000 IU weekly for 4 weeks and then 60,000 IU monthly over the 12 months study.
Fasting plasma glucose (FPG), 2‑h plasma glucose and A1C levels were estimated at 0, 6 and 12 months. Changes in FPG, 2‑h plasma glucose, A1C level and the proportion of subjects developing diabetes were assessed among 129 subjects.
|Figure 1: Rel. changes in BMI, fasting blood glucose (FPG), 2h post-prandial glucose and A1C (left) as well as relative incidence of type II diabetes development in subjects over the 12-months study period (Kuchay. 2015).|
Don't forget to take your vitamin D with fat: While vitamin D does not take as much fat for optimal absorption as other fat soluble vitamins, having your supplements with a fatty meal may still improve their effects on your 25OHD levels | Learn more.
|Figure 2: Subgroup analysis of the effects of D-supplementation on subjects with baseline low vs. high 25OHD (Kuchay. 2015)|
FPG, 2‑h plasma glucose and A1C levels at 12 months.
This change was, however, less pronounced in those subjects who had baseline Vitamin D levels above 30 ng/mL" (Kuchay. 2015).
- Kuchay, M. S., et al. "Effect of Vitamin D supplementation on glycemic parameters and progression of prediabetes to diabetes: A 1-year, open-label randomized study." Indian Journal of Endocrinology and Metabolism 19.3 (2015): 387.