Have you had your vitamin D level checked recently? This is the time of year when levels tend to hit the bottom. That’s because you probably have not been exposing much skin to the sun’s rays. That could spell trouble ahead.
Q. My doctor just told me I am borderline diabetic with a blood sugar reading of 115. He also said I have very low vitamin D levels. He recommended 5,000 IUs of vitamin D3 daily for several months. Then he wants to measure my fasting blood sugar and vitamin D levels again. Why would vitamin D have anything to do with diabetes?
A. Vitamin D affects genes that direct a surprising number of activities in the body (PLOS One, March 20, 2013). Swedish researchers have found that people with prediabetes are less likely to develop full-blown diabetes if they have high vitamin D levels (Diabetologia, June, 2012).
Another study from Sweden (Acta Paediatrica, online, Feb. 12, 2016) revealed that roughly one third of overweight teenagers had low vitamin D levels and this was associated with pre-diabetes.
Disappointing Results with Weekly Dosing:
For reasons that mystify us, researchers like to give subjects once weekly doses of vitamin D instead of daily doses. Our gut opinion is that moderate daily dosing might produce more interesting results than large weekly or monthly doses.
A Norwegian study published in Diabetes Care (Aug. 2014) found that 20,000 IUs of vitamin D3 given once a week in capsules did not improve blood sugar control in people with prediabetes.
A Swedish study also found no improvement when subjects were given 30,000 IU once a week for eight weeks (Diabetes Care, online, Jan. 19, 2016).
We haven’t seen any studies that show taking daily vitamin D supplements can normalize blood sugar, but it is certainly worth a try. We hope you’ll let us know the results of your one-person experiment.
We discuss many approaches to preventing type 2 diabetes in our Guide to Managing Diabetes. Those concerned about low vitamin D levels may also find our Guide to Vitamin D Deficiency of interest.
Revised: February 18, 2016
