January 13th, 2011
11:35 AM ET

Do vitamins help against type 2 diabetes?

Every weekday, a CNNHealth expert doctor answers a viewer question. On Wednesdays, it's Dr. Otis Brawley, chief medical officer at the American Cancer Society.

Question asked by Melissa Dashensa of San Diego, California

Are vitamin D, calcium and magnesium effective in preventing type 2 diabetes? If so, how much should one take?

Expert answer:

You ask a fascinating question that is currently of great interest to medical researchers. Vitamin D is commonly found in fish, eggs, fortified milk, cod liver oil and in supplements. It helps regulate blood calcium levels and maintain bone health. Very recently the Institute of Medicine of the prestigious U.S. National Academy of Science published a review of the scientific literature and noted that vitamin D may be linked to heart disease, immune function, cancer prevention and diabetes. It is definitely linked to bone health.

Type 2 diabetes, which is also called adult onset diabetes, is a growing problem in the Western world and is most common in the overweight and the obese. It occurs when cellular tissues develop resistance to insulin stimulation. This is referred to as "insulin resistance." The result is insulin is not able to move glucose from blood into the cells and the blood glucose level rises.

How well are you managing your diabetes? Take this test

There is some data to suggest that vitamin D may decrease insulin resistance. For example, in one study of 124 people with type 2 diabetes, researchers found 113 (91.1%) had vitamin D deficiency. hemoglobin A1C is used to determine blood glucose control over the past three months or so. The average hemoglobin A1C level was higher (meaning less than optimal control) in patients with the most severe vitamin D deficiencies. This is not adequate evidence to show that vitamin D deficiency causes diabetes nor that vitamin D supplementation is a legitimate treatment for diabetes. It simply shows that there is a correlation between vitamin D level and glucose control. This being said, it is not inappropriate for a diabetic to ask their physician to check their vitamin D level every year or so and for a physician to prescribe supplements if it is low. Calcium levels in the blood are routinely checked in most standard laboratory panels.

There are also several studies published in the past 10 years that correlate a low magnesium intake or low level of magnesium in the blood with greater risk of development of diabetes. The design of these studies is very similar to the vitamin D studies. They show a correlation and not a causation.

It is a good idea to read nutrition content on food labels to see if you are getting enough vitamin D, calcium or magnesium. The recent Institute of Medicine study recommends everyone age 1 to 70 take 600 international units (IU) per day of vitamin D and those over 71 take 800 IU. The institute recommends adolescents age 9 to 18 receive 1,300 mg per day of elemental calcium. Women age 19 to 50 should take 1,000 mg of elemental calcium. Women should increase to 1,200 mg starting at age 51. Men should take 1,000 mg of elemental calcium from age 19 to age 70 and increase to 1,200 mg at age 71. Too much vitamin D and/or calcium can lead to kidney stones. No more than 4,000 IU of vitamin D should be consumed daily and no more than 2,000 mg of calcium.

Magnesium is found in nuts, beans, whole grains and green leafy vegetables magnesium levels are generally good in people who have a balanced diet. Like calcium, most physicians check it routinely and will obtain dietary counseling for moderately low levels or prescribe replacement if the level is very low. The recommended daily requirements for adolescent and adult males are 270 to 400 mg per day. Adolescent and adult females should get 280 to 300 mg per day. Pregnant and breastfeeding women should get more: 320 to 355 mg.

Ultimately, what we need is a study that randomizes people at high risk of developing diabetes into four groups. One to receive supplementation with vitamin D, one with magnesium, one with both, and one with placebo (an inactive drug). After several years of follow-up and comparison of the four groups we can determine if vitamin D or magnesium is useful in preventing diabetes. Smaller and shorter term prospective studies could be done to see if vitamin D and magnesium are good treatments for people who already have diabetes.

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soundoff (27 Responses)
  1. ShrNfr

    As a note, Cinnamon appears to have a positive effect on type 2 diabetes. Poke around on web for more official stuff including government studies on it.

    January 13, 2011 at 12:16 | Report abuse | Reply
    • The_Mick

      I have type II diabetes and looked into it. The latest studies indicate cinnamon doesn't help.

      January 13, 2011 at 21:47 | Report abuse |
    • rav

      for type 2 DM, minerals are way to go to be exact SELENIUM, because SELENEIUM increases release of insulin. Have no idea why all these physicians, and phds who are wasting dollars forgetting basic sciences, i mean duh whats the mechanism of DM, i bet no doctor knows..oh wait they know what it says on article but they probably don;t want to challenge who wrote it.

      January 19, 2011 at 18:37 | Report abuse |
  2. IANAD

    In recent studies asking whether baths containing epsom salts (magnesium sulfate) actually penetrated the skin and elevated magnesium levels, the findings were positive. They do.

    While I'm certain that supplements can provide enough or more magnesium for a body, with extremities like toes and feet often suffering first, taking an epsom salt bath regularly can provide an opportunity to inspect feet and toes for unusual, early-warning bruising. Wouldn't hurt anyway.

    It is also well-understood that dehydration can occur while taking a bath, so milk or another calcium-rich drink might be a good idea concomitantly.

    January 13, 2011 at 13:18 | Report abuse | Reply
  3. Marianne Bailey

    Where is John Roberts. I haven't seen him on CNN in the mornings lately?

    January 13, 2011 at 13:40 | Report abuse | Reply
    • Jay

      John is a Great Guy – apparently he's now moved over to Fox...

      January 13, 2011 at 14:01 | Report abuse |
  4. Liz @ HEALing Foodie

    Type 2 diabetes is no longer called adult-onset diabetes because many young adults and even kids are being diagnosed with the disease now.

    Ultimately, well-balanced meals that are part of a healthy lifestyle will supply the necessary vitamins and minerals. Unless otherwise specified, supplements may pose more health risks than benefits.

    January 13, 2011 at 13:44 | Report abuse | Reply
    • Jay Rosenfeld

      Liz, would you please provide the evidence for your comments? thank-you

      January 13, 2011 at 15:49 | Report abuse |
  5. Spirit Happy is a scam diet.

    My favorite quote from the Spirit Happy diet blog is:


    Oh yeah. Nothing says medical and scientific expertise like "FILMMAKER".
    There ARE effective diets for assisting in controlling type 2 diabetes, and you don't have to pay $17 just to read about them.
    Talk to an actual nutritionist, or even your doctor, about what diets may help you. Not every diet works for everyone, and some diets can harm you if you don't know enough about them or your body.

    January 13, 2011 at 13:45 | Report abuse | Reply
  6. SpartanXD

    I lowered my A1C's from 10.1 to 5.9 in 3 months. I had to completely change what I was doing, and switch to a low-carb/good-carb diet (in other words, no white bread, high fructose corn syrup, etc.) and started strength training. 3 months after that, my doctor said I was no longer a diabetic. Its been 3 years now and my diabetes has been reversed with a low-carb/good carb diet and exercise.

    January 13, 2011 at 14:56 | Report abuse | Reply
  7. Yakobi.

    B.S. This is a scam. Peddle your nonsense elsewhere.

    January 13, 2011 at 16:18 | Report abuse | Reply
  8. Dowdypants

    Here's the truth about Type 2 Diabetes:

    You don't "catch" it, and it's completely "curable". Cut down on overall carbs. No more simple sugars. There, epidemic solved.

    January 13, 2011 at 18:07 | Report abuse | Reply
    • cdd

      Please provide clinical studies and conclusions to support your claim. There are too many studies from accredited hospitals and doctors that say otherwise

      January 14, 2011 at 02:06 | Report abuse |
  9. Mike

    Get out of here, snake oil salesman!

    January 13, 2011 at 19:30 | Report abuse | Reply
  10. Karen

    Diabetes Mellitus Type 2 (DMT2) is the result of a long term and worsening insulin resistance. Insulin resistance is caused by consuming too much carbs too often. By reducing strongly and even better by largely avoiding the intake of carbohydrates, the chronically high blood sugar levels and needs for insulin can vanish. More about diabetes you can read here: http://www.cutthecarb.com/category/diabetes/

    January 14, 2011 at 05:21 | Report abuse | Reply
  11. Leticia

    Don't you mean that Vitamin D *deficiency* is linked to all these potential problems? The way your article is written, it sounds like Vitamin D is the problem, not the solution.

    January 14, 2011 at 07:42 | Report abuse | Reply
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    January 21, 2011 at 04:47 | Report abuse | Reply
  13. BadPatient

    No...especially if you are allergic to corn and they are using corn to get vitamin c. not helpful. just adds to and confounds the problem.

    January 28, 2011 at 10:32 | Report abuse | Reply
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    Since July last yr I have been on "the blood diet" except for feet complications I have never felt better, lost weight easier, or been as positive about any diet. I will never go back to the "American diet". It is called controlling your food, not food controlling you. The American diet is killing us!

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Get a behind-the-scenes look at the latest stories from CNN Chief Medical Correspondent, Dr. Sanjay Gupta, Senior Medical Correspondent Elizabeth Cohen and the CNN Medical Unit producers. They'll share news and views on health and medical trends - info that will help you take better care of yourself and the people you love.

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