Vitamin D and Diabetes, A Randomized Placebo Controlled Trial Shows the IOM was too Cautious

July 07, 2011

Vitamin D and Diabetes, A Randomized Placebo-Controlled Trial Shows the IOM was too Cautious 

Reference: Endo Meta Clin N A, AJCN July 2011 Author Joanna Mitri from Harvard School of Public Health Competency:  Vitamin D 

Yeah!  A Randomized placebo-controlled trial that unequivocally shows that Vitamin D works with diabetes in improving pancreatic function.  Dr. Mitri and her team had to work hard to get this study done. They had to screen over 911 subjects to get 44 perfectly matched folks with diabetes that were split into 22 and 22 subjects.  They had 45 in a parallel control group who got a bit of calcium as their treatment option.  The study only ran for 12 weeks but that was enough to show meaningful changes. 

What did they look at?  The ability of the pancreas to secrete insulin and control blood sugar is the whole story of diabetes.   This study looked at a composite index of pancreatic function and showed that the Vitamin D group improved their function by a score of 300 while the control group dropped 126 points.  That was statistically significant to a very high degree. As we get heavier and put on weight (these folks were an average BMI of 31) we soak up more vitamin D into our fat tissues.  It’s hard to raise your D level when you are overweight.   In this study they only raised their Vitamin D levels from 24 to 30 ng with the 2000 IU dose they gave.  So, that was cautious to say the least.   But the study only ran 12 weeks.   

Readers of this column will know that 2000 IU will raise your blood level by about 20 ng if you stick with it for a year.   And from our Antarctic study, we know that 2000 IU will never get you much higher than 30 ng, which is about what this study accomplished with folks living in Boston where they had sunshine, some of the time. What’s the meaning of this study?  It’s huge.  We ALL have diabetes risk as we get a little chubby.  Much of it is subclinical.  If you have a blood sugar of just 102, your doctor will tell you to lose a bit of weight and exercise more.  

Now, the script changes.  Lose weight, exercise more, and make sure you are on at least 2000 IU.  We know from the American College of Cardiology meetings last year that Vitamin D levels of 45 and above correlate with a reduction in cardiac risk of some 70%, so a level of 30 is cautious, but in the right direction. This is the first good RCT (randomized placebo-controlled trial) of 2000 IU on diabetes that I’ve seen.  This is good science. We now can unequivocally state that any recommendation of Vit D less than 2000 IU for someone at risk for diabetes is not enough. 

 WWW.  What will work for me?  Well, I want a D level of 60-80 by my read of the literature.  But I’m projecting from physiology studies that show continuing improvement in function.  This is a study showing outcomes to match.  We now need the same study giving 5000 iu a day, and just aiming for blood levels of 60. ng  It’ll come.  And I’ll try not to gloat.  (And my two minutes are now up.)

The column was written by Dr John E. Whitcomb, MD, Brookfield Longevity, Brookfield, WI.