Vitamin D and Diabetes

vitamin d logoVitamin D is one of the more fascinating substances I have researched in the diabetes arena. It provides a number of important functions, regardless of whether you have diabetes or not. I will discuss these issues more fully below, but the good stuff really comes when you start looking at the impact of the substance on diabetes.

Multiple studies suggest that the impact on both type 1 and type 2 diabetes is startling. While I caution that research is ongoing, initial results suggest that vitamin D deficiency may be a significant cause of diabetes, which means there may be hope to stop people from getting it. Additionally, vitamin d may play a role in slowing the progression of diabetes if you already have it.

So, what exactly is Vitamin D? Vitamin D is actually not a vitamin at all. It is a hormone. Initially discovered in the 1930’s, vitamin D was originally “famous” for helping children avoid contracting rickets. Rickets is a disease where the bones don’t develop or harden properly.

If you have ever watched the Lil Rascals television show, you may remember the funny scenes where the kids were required to consume cod liver oil. Back then, scientists didn’t know that cod liver oil (and other fish sources) was a good source of vitamin D. They only knew that the oil helped the kids avoid rickets!

Upon vitamin D’s discovery, you now see one of the main reasons it was added to milk. The other reason is that vitamin D is needed to process calcium to help your bones stay strong. Among other reasons, calcium is also important to help your nervous system and muscles work properly. Calcium wouldn’t work without vitamin D helping it out.

As we will touch on more below, vitamin D may also help the following:

  • Avoid Cancer (colon, prostate, breast, ovarian)
  • Reduce Heart Disease
  • Avoid or Minimize Type 1 and Type 2 Diabetes
  • Reduce Risk of Developing MS, Alzheimer’s, Parkinson’s
  • Avoid or Improve Certain Mental Health Conditions (e.g., depression)

Diabetes Connection

I would first note that the following research is very compelling. However, there is still some debate amongst scientists. Probably, the best summation of the diabetes and vitamin D connection was done by Dan Hurley in his book Diabetes Rising. I review his excellent book Here. I encourage everyone to read Dan’s excellent book on this topic.

For both type 1 and type 2 diabetes, the increased prevalence during the last 20-30 years has been nothing short of breathtaking. What was once a fairly uncommon disease has risen to the level of an epidemic. One explanation, or contributing factor, for this rise is that people are spending more and more time indoors and/or lathered in sunscreen. These two factors directly contribute to a reduction in vitamin D.

Think about, how much time do you spend watching TV? How much time do you, your kids or grand kids spend playing video games? If we are honest, too much!

Type 1

In one 30 year study of children in Scandinavia (think long winters with little sunlight), it found that children were almost 80 percent less likely to develop type 1 diabetes if given a daily vitamin D supplement of 2,000 IU. This is a remarkable difference. Conversely, other studies have found that children living in sunnier climates are far less likely to develop type 1 diabetes than their counterparts living in gloomier northern climates.

But, it may not just help you avoid diabetes, it may also help you slow the progression. Vitamin D may help slow the destruction of beta cells in people with type 1 diabetes. Of course, if you have had type 1 for years this probably isn’t going to do you any good. However, if you are newly diagnosed with type 1, you may still have some insulin producing beta cells remaining. A sharp increase in vitamin D supplementation may help sustain these cells, thus reducing your long term needs for larger doses of insulin.

This last assertion is open to some speculation. However, if you or a loved one is recently diagnosed with type 1, talk to your doctor immediately. As discussed below, there typically is no toxicity with increasing vitamin D intake (to a certain point), so there should be no harm in supplementing. Get to your doctor to discuss!!

Type 2

Here is where it gets even more interesting, if this is possible. There have been several European studies that suggest that decreased vitamin D levels in people reduce insulin production and increases insulin resistance.

This is bad right? Basically your body produces less insulin and doesn’t use the insulin it does produce well. This is the very problem facing people with type 2 diabetes. Here are some other studies that look into the relationship between Vitamin D and diabetes.

Reduced Risk of Developing Type 2 Diabetes: A large United States based study theorized that increased vitamin D intake in women significantly lowered their risk of developing type 2 diabetes. While I would note that this study was not looking specifically at this issue, there was, however, a very strong correlation (33 percent) in its overall conclusion.

Poor Glucose Control: A 2010 John’s Hopkins study of 124 people with type 2 diabetes found that 91 percent of them had a vitamin D deficiency. Interestingly enough, the greater the deficiency the worse the subjects A1C levels were. The study noted that racial minorities tended to be more vitamin D deficient. While the study stopped short of concluding that vitamin D deficiency is the cause of poor glucose control, it did advocate that all people with diabetes be screened for the deficiency.

Increased Insulin Sensitivity: A small study released in 2011 by the Albert Einstein College of medicine looked at 8 vitamin D deficient patients. The subjects received large daily doses of vitamin d for two months to get them to normal levels. At the end of the two months, insulin receptivity (the ability of your cells to use insulin) increased by 37 percent. This is a remarkable increase.

There are many more studies, but you get the point. Vitamin D may help prevent diabetes and may help with glucose control if you already have the condition. I would note that most researchers agree that further study is needed to definitively establish the link.

How Much Should You Take?

Here is where things get a little murky. The National Institute of Health has set forth the following Recommended Daily Allowances (RDA):

0-12 Months400 IU (10mcg)400 IU (10mcg)
1-13 Years600 IU (15mcg)600 IU (15mcg)
14-18 Years600 IU (15mcg)600 IU (15mcg)600 IU (15mcg)600 IU (15mcg)
19-50 Years600 IU (15mcg)600 IU (15mcg)600 IU (15mcg)600 IU (15mcg)
51-70 Years600 IU (15mcg)600 IU (15mcg)
70+ Years800 IU (15mcg)800 IU (15mcg)

The NIH has established the upper limit of vitamin D intake:

0-6 Months1,000 IU (25 mcg)1,000 IU (25 mcg)
7-12 Months1,500 IU (38 mcg)1,500 IU (38 mcg)
1-3 Years2,500 IU (63 mcg)2,500 IU (63 mcg)
4-8 Years3,000 IU (75 mcg)3,000 IU (75 mcg)
9 Years and Older4,000 IU (100mcg)4,000 IU (100mcg)4,000 IU (100mcg)4,000 IU (100mcg)

I would note that some scientists suggest 2,000 IU daily for best results. My suggestion would be to check with your doctor and establish a plan that is safe for you.


vitamin d and sunshine
Natural Sunlight: The safest way to get your vitamin D is through natural sunlight. If you are Caucasian and not very tan, then 10-15 minutes in the sun with a short sleeve shirt and shorts is plenty. If you are tan or have darker skin, then you need approximately 20 minutes. There is no toxicity risk of receiving too much of the vitamin in this manner.

The problem is that if you live in a northern climate, even if you joined a polar bear club and ran around naked for 3 hours a day outside, you still couldn’t get enough. Which leads us to the next two options.

Food: Food sources are somewhat limited. You could eat fortified foods, such as milk, orange juice or cereal. Additionally, the highest natural food sources per serving are:

  • Cod Liver Oil (1 tablespoon) 1,360 IU
  • Swordfish (3 oz.) 566 IU
  • Salmon (3 oz.) 447 IU

As you can see, if you want to achieve a higher amount of daily intake, it is hard with natural foods.

Supplements: For people who work indoors or live in a northern climate, supplementation is typically the only way to get the higher intake of vitamin D. When you go to the store to purchase your supplements, you will notice that there are two different types, D2 and D3.

At lower levels, most scientists suggest there is not a big difference between the two types of vitamin D. However, if you are looking to do some of the higher doses, then there is a difference and I typically see D3 recommended. The issue is that D3 is much more effective than D2 at the higher levels.

Again, check with your doctor to determine the right plan for you.

US News & World Report (accessed July 2013). (accessed July 2013). (accessed July 2013). (accessed July 2013).
Vitamin D and Diabetes May 2011, Publication (accessed July 2013).