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Should You Supplement?


Learn if complementary health approaches are safe with diabetes

Conventional medical treatments and following a healthy lifestyle, including watching your weight, can help you prevent, manage, and control many complications of diabetes. Researchers are studying several complementary health approaches, including dietary supplements, to see if they can help people manage type 2 diabetes or lower their risk of developing the disease. It is very important not to replace proven conventional medical treatment for diabetes with an unproven health product or practice.


Herbal Supplements for Diabetes

There is no strong evidence that herbal supplements can help to control diabetes or its complications.

  • Researchers have found some risks but no clear benefits of cinnamon for people with diabetes.
    • A 2012 systematic review of 10 randomized controlled trials did not support using cinnamon for type 1 or type 2 diabetes.
    • A trial of 59 people with type 2 diabetes found that a combination of cinnamon, calcium, and zinc didn’t improve their blood pressure.
    • When researchers tested samples of the common spice cassia cinnamon for sale at grocery stores in Europe, they found many samples contained coumarin, a substance that may cause or worsen liver disease in people who are sensitive. Also, eating large amounts of cinnamon containing coumarin may be especially risky for people taking blood-thinning drugs; the interaction of coumarin and blood thinners can increase the likelihood of bleeding.
  • Researchers are studying whether Asian ginseng and American ginseng may help control glucose levels. Currently, research reviews and clinical trials show that there is not enough evidence to support their use.
  • Other herbal supplements studied for diabetes include aloe vera, bitter melon, Chinese herbal medicines, fenugreek, garlic, Gymnema sylvestre, milk thistle, nettle, prickly pear cactus, and sweet potato. None have been proven to be effective.

Are Herbal Supplements Safe for Diabetes?

Information on the safety of herbal supplements for people with diabetes is generally inconclusive or unavailable. Interactions between herbs and conventional diabetes drugs have not been well studied and could be a health risk. For example, in some people cinnamon might worsen liver disease and interact with blood thinners.


Omega-3s for Diabetes

Omega-3s supplements don’t help people with diabetes control their blood sugar levels, a 2008 systematic review found. A 2012 study that combined a meta-analysis and a systematic review looked at the possible link between eating seafood or plants with omega-3s and the risk of developing type 2 diabetes. The study found little evidence that these dietary sources of omega-3s affected the risk of developing diabetes.

Are Omega-3 Supplements Safe for Diabetes?

  • Omega-3 supplements usually do not have negative side effects. When side effects do occur, they typically consist of minor gastrointestinal symptoms, such as belching, indigestion, or diarrhea.
  • Omega-3 supplements may extend bleeding time (the time it takes for a cut to stop bleeding). People who take drugs that affect bleeding time, such as anticoagulants (“blood thinners”) or nonsteroidal anti-inflammatory drugs (NSAIDs), should discuss the use of omega-3 fatty acid supplements with a health care provider.


Vitamins and Minerals for Diabetes

  • Studies (including a 2010 research review and 2009 clinical trial) have found no evidence that taking vitamin C supplements is helpful for diabetes.
  • There is no evidence from clinical trials that magnesium helps to manage diabetes.
    • A 2011 meta-analysis reviewed the results of 13 studies that looked at how much magnesium people got in their diets, either through supplements or food, and their risk of diabetes. The review found that people who had lower magnesium intake had a greater risk of developing diabetes.
    • One of the studies in the 2011 research review mentioned above, a large 2007 clinical trial, found that people who ate more cereal fiber and magnesium-rich food had a lower risk of developing type 2 diabetes.
    • People who had a diet rich in magnesium had a 15% reduced risk of developing type 2 diabetes, according to a 2007 meta-analysis of studies that looked at magnesium from foods or supplements.
  • The research on diabetes and vitamin D and calcium supplements is not conclusive.
    • Supplementing with vitamin D combined with calcium appears to lower the risk of developing type 2 diabetes, according to a 2007 systematic review and meta-analysis.
    • In a 2008 clinical trial studying 33,951 post-menopausal women over 7 years, calcium plus vitamin D supplements did no better than a placebo at reducing the risk of developing diabetes.
    • The lower risk seen in some studies in people who consume more calcium may be because those individuals are also getting more magnesium, a 2012 meta-analysis reported.

Are Vitamins and Minerals Safe for Diabetes?

Getting too much calcium may interfere with the body’s ability to absorb iron and zinc. Also, calcium supplements can interact with certain medicines.

No serious side effects were reported in studies where people with diabetes were given magnesium supplements for up to 16 weeks. However, the long-term safety of magnesium supplements for people with diabetes has not been established. Large doses of magnesium in supplements can cause diarrhea and abdominal cramping. Very large doses — more than 5,000 mg/day per day — can be deadly.


Published on March 11, 2015.


Source: National Center for Complementary and Integrative Health. November 2013.

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