What’s the Bottom Line?

How much do we know about dietary supplements for diabetes?

• Many studies have investigated dietary supplements for preventing or treating type 2 diabetes or its complications (the focus of this fact sheet).

What do we know about the effectiveness of dietary supplements for diabetes?

• For a few dietary supplements, there is weak evidence of a possible benefit. For example, chromium might help with blood sugar control, and alpha-lipoic acid might be helpful for diabetic neuropathy (nerve problems). For most supplements, however, there isn’t evidence to support a beneficial effect on diabetes or its complications.

What do we know about the safety of dietary supplements for diabetes?

• Some dietary supplements may have side effects, and some of these side effects, such as kidney damage, can be serious.
• The U.S. Food and Drug Administration (FDA) is warning consumers about products for diabetes that seem too good to be true, such as those that claim to be a “natural diabetes cure” or to “replace your diabetes medicine.” These products are marketed illegally. Some are harmful in themselves, and all are harmful if people use them in place of effective diabetes treatment.
• It’s very important not to replace medical treatment for diabetes with an unproven health product or practice.

About Diabetes

• Diabetes is a disease that occurs when your blood glucose, also called blood sugar, is too high. Over time, having too much glucose in your blood can cause health problems.
• About 9.4 percent of the people in the United States have diabetes, but about one in four people who have diabetes don’t know it.
• Although diabetes has no cure, people with diabetes can take steps to manage their condition and stay healthy. Taking insulin or other diabetes medicines is often part of treating diabetes, along with healthy food choices and physical activity.
• The most common type of diabetes is type 2 diabetes, in which your body does not make or use insulin well. This type of diabetes occurs most often in middle-aged and older people, but it can develop at any age, even in childhood.
• You are more likely to develop type 2 diabetes if you are 45 years old or older, have a family history of diabetes, or are overweight. Physical inactivity, race, certain health problems such as high blood pressure, having prediabetes, or having had gestational diabetes while pregnant also affect your likelihood of developing type 2 diabetes.

Kidney disease has been linked to using some dietary supplements. This is of particular concern for people with diabetes, since diabetes is the leading cause of kidney disease. If you have or are at risk for kidney disease, a health care provider should closely monitor your use of supplements.

What the Science Says About the Effectiveness and Safety of Dietary Supplements for Diabetes

Alpha-Lipoic Acid

• Alpha-lipoic acid is being studied for its effect on complications of diabetes, including diabetic macular edema (an eye condition that can cause vision loss) and diabetic neuropathy (nerve damage caused by diabetes).
  • In a 2011 study of 235 people with type 2 diabetes, 2 years of supplementation with alpha-lipoic acid did not help to prevent macular edema.
  • A 2016 assessment of treatments for symptoms of diabetic neuropathy that included 2 studies of oral alpha-lipoic acid, with a total of 205 participants, indicated that alpha-lipoic acid may be helpful.
• Safety
  • High doses of alpha-lipoic acid supplements can cause stomach problems.

Chromium

• Found in many foods, chromium is an essential trace mineral. If you have too little chromium in your diet, your body can’t use glucose efficiently.
  • Taking chromium supplements, along with conventional care, slightly improved blood sugar control in people with diabetes (primarily type 2) who had poor blood sugar control, a 2014 review concluded. The review included 25 studies with about 1,600 participants.
• Safety
  • Chromium supplements may cause stomach pain and bloating, and there have been a few reports of kidney damage, muscular problems, and skin reactions following large doses. The effects of taking chromium long-term haven’t been well investigated.

Herbal Supplements

• We don’t have reliable evidence that any herbal supplements can help to control diabetes or its complications.
  • There are no clear benefits of cinnamon for people with diabetes.
  • Other herbal supplements studied for diabetes include bitter melon, various Chinese herbal medicines, fenugreek, ginseng, milk thistle, and sweet potato. Studies haven’t proven that any of these are effective, and some may have side effects.
• Safety
  • We have little conclusive information on the safety of herbal supplements for people with diabetes.
  • Cassia cinnamon, the most common type of cinnamon sold in the United States and Canada, contains varying amounts of a chemical called coumarin, which might cause or worsen liver disease. In most cases, cassia cinnamon doesn’t have enough coumarin to make you sick. However, for some people, such as those with liver disease, taking a large amount of cassia cinnamon might worsen their condition.
  • Using herbs such as St. John’s wort, prickly pear cactus, aloe, or ginseng with conventional diabetes drugs can cause unwanted side effects.

Magnesium

• Found in many foods, including in high amounts in bran cereal, certain seeds and nuts, and spinach, magnesium is essential to the body’s ability to process glucose.
  • Magnesium deficiency may increase the risk of developing diabetes. A number of studies have looked at whether taking magnesium supplements helps people who have diabetes or who are at risk of developing it. However, the studies are generally small and their results aren’t conclusive.
• Safety
  • Large doses of magnesium in supplements can cause diarrhea and abdominal cramping. Very large doses—more than 5,000 mg per day—can be deadly.

Omega-3s

• Taking omega-3 fatty acid supplements, such as fish oil, hasn’t been shown to help people who have diabetes control their blood sugar levels or reduce their risk of heart disease.
• Fish and other seafood, especially cold-water fatty fish such as salmon and tuna, contain omega-3 fatty acids. Studies on the effects of eating fish have had conflicting results, according to two 2012 research reviews with hundreds of thousands of participants, and a 2017 review. Some research from the United States and Europe found that people who ate more fish had a higher incidence of diabetes. Research from Asia and Australia found the opposite—eating more fish was associated with a lower risk of diabetes. There’s no strong evidence explaining these differences.
• Safety
  • Omega-3 supplements don’t usually have side effects. When side effects do occur, they typically consist of minor symptoms, such as bad breath, indigestion, or diarrhea.
  • Omega-3 supplements may interact with drugs that affect blood clotting.

Selenium

• An assessment of 4 studies involving more than 20,000 total participants found that selenium supplementation did not reduce the likelihood that people would develop type 2 diabetes.
• Safety
  • Long-term intake of too much selenium can have harmful effects, including hair and nail loss, gastrointestinal symptoms, and nervous system abnormalities.

Vitamins

• Studies generally show that taking vitamin C doesn’t improve blood sugar control or other conditions in people with diabetes. However, a 2017 research review of 22 studies with 937 participants found weak evidence that vitamin C helped with blood sugar in people with type 2 diabetes when they took it for longer than 30 days.
• Having low levels of vitamin D is associated with an increased risk of developing a metabolic disorder, such as type 2 diabetes, metabolic syndrome, or insulin resistance, studies and research reviews from the past 5 years have found. However, taking vitamin D doesn’t appear to help prevent diabetes or improve blood sugar levels for adults with normal levels, prediabetes, or type 2 diabetes, a 2014 research review of 35 studies with 43,407 participants showed.
• Safety
  • Taking too much vitamin D can cause nausea, constipation, weakness, kidney damage, disorientation, and problems with your heart rhythm. You’re unlikely to get too much vitamin D from food or the sun.

Other Supplements

• The evidence is still very preliminary on how supplements or foods rich in polyphenols—antioxidants found in tea, coffee, wine, fruits, grains, and vegetables—might affect diabetes.

Nutrition and Physical Activity for People With Diabetes

Nutrition and physical activity are important parts of a healthy lifestyle for people with diabetes. Eating well and being physically active can help you

• Keep your blood glucose level, blood pressure, and cholesterol in your target ranges
• Lose weight or stay at a healthy weight
• Prevent or delay diabetes problems
• Feel good and have more energy.

More To Consider

• The FDA is warning consumers not to buy illegally marketed, potentially dangerous products claiming to prevent, treat, or cure diabetes. These products make claims like “lowers your blood sugar naturally” or “inexpensive therapy to fight and eliminate type II diabetes.” They may contain harmful ingredients and the label may not tell you what you’re actually taking.
• Fraudulent diabetes products can be especially dangerous if you use them instead of proven treatments for diabetes. Without proper disease management, people with diabetes are at greater risk of developing serious complications.
• Keep in mind that dietary supplements may interact with medications or other dietary supplements.
• Take charge of your health—talk with your health care providers about any complementary health approaches you use. Together, you can make shared, well-informed decisions.

Two clinical trials involving approximately 570 participants found that alpha-lipoic acid supplements did not prevent or improve conditions related to diabetes.

What Does the Research Show?

Several studies have examined the effects of alpha-lipoic acid on complications of diabetes.

• A 2011 clinical trial of 467 participants with type 2 diabetes found that 600 milligrams of alpha-lipoic acid daily did not prevent diabetic macular edema, an eye condition that causes blurred vision.
• Alpha-lipoic acid and vitamin E supplements taken separately or in combination did not improve cholesterol levels or the body’s response to insulin in a 2011 clinical trial of 102 people with type 2 diabetes.

Safety

• High doses of alpha-lipoic acid can cause gastrointestinal upset.

Clinical trials have found few or no benefits of chromium supplements for controlling type 2 diabetes or reducing the risk of developing it.

What Does the Research Show?

Several clinical trials have been conducted to examine the effects of chromium for controlling or preventing type 2 diabetes; however, many of these studies have been very small or not of high quality.

• A 2014 systematic review and meta-analysis of 25 randomized controlled trials involving approximately 1,600 participants concluded that available evidence suggests favorable effects of chromium supplementation on glycemic control in patients with diabetes. Long-term benefits of chromium supplementation remain to be investigated.
• A 2015 randomized controlled trial involving 62 moderately obese or overweight pre-diabetic participants concluded that a 4-month treatment with a dietary supplement containing cinnamon, chromium, and carnosine decreased fasting plasma glucose and increased fat-free mass in these participants.
• A 2015 review of 14 randomized controlled trials involving 875 participants concluded that chromium supplementation with brewer’s yeast may provide modest benefits in lowering fasting blood glucose in people with type 2 diabetes compared with placebo; however, it did not have any effect on A1c.

Safety

• Chromium supplements may cause stomach pain and bloating, and there have been a few reports of kidney damage, muscular problems, and skin reactions following large doses.
• The 2014 systematic review and meta-analysis mentioned above concluded that chromium supplementation at usual doses does not increase the risk of adverse events compared with placebo. Long-term safety of chromium supplementation remains to be investigated.

Data from clinical trials have shown no clear benefits and some risks of cinnamon for people with diabetes.

What Does the Research Show?

There have been several randomized controlled trials as well as a Cochrane review that have examined the effects of cinnamon in people with diabetes.

• A 2013 systematic review and meta-analysis of 10 randomized controlled trials involving 543 participants concluded that cinnamon was associated with a statistically significant decrease in levels of fasting plasma glucose, total cholesterol, LDL-C, and triglyceride levels, and an increase in HDL-C levels; however, no significant effect was seen on hemoglobin A1c levels. The reviewers noted that the high degree of heterogeneity of the studies (i.e., the dose and duration of treatment are unclear) included in the analyses may limit the ability to apply these findings to patient care.
• A 2012 Cochrane systematic review of 10 randomized controlled trials involving a total of 577 participants found insufficient evidence to support the use of cinnamon for type 1 or type 2 diabetes.

Safety

• Cassia cinnamon, the most common type of cinnamon sold in the United States and Canada, contains varying amounts of coumarin, a substance that may cause or worsen liver disease.

Clinical trial results on efficacy of magnesium supplementation for type 2 diabetes is limited; some benefits have been found in several, but not all studies.

What Does the Research Show?

The increased risk of developing type 2 diabetes in people with magnesium deficiency has suggested that magnesium supplementation may provide benefits to those patients with type 2 diabetes or those at risk for developing the disease. However, results from clinical trials have not yet shown a clear benefit.

• A 2015 review concluded that benefits of magnesium supplementation on metabolic profiles in diabetic patients have been found in some, but not all clinical studies, and larger prospective randomized controlled trials are needed to support the possible role of magnesium supplementation for the management of type 2 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. Of the 13 selected studies, 9 found a statistically significant inverse association between magnesium intake and diabetes risk. That is, people who had lower magnesium intake had a greater risk of developing diabetes.

Safety

• Large doses of magnesium in supplements can cause diarrhea and abdominal cramping. Very large doses—more than 5,000 mg per day—can be deadly.

Omega-3 fatty acid supplementation has not been shown to improve blood glucose levels in people with diabetes.

What Does the Research Show?

Much research has examined the role of omega-3 fatty acids in reducing the risk of developing type 2 diabetes.

• A 2017 American Heart Association science advisory, based on 5 studies with more than 10,000 participants concluded that overall evidence from randomized controlled trials suggests no benefit of omega-3 fatty acid supplements among patients with or at risk for diabetes to prevent cardiovascular disease.
• A 2008 Cochrane systematic review of 23 randomized controlled trials involving 1,075 participants found that omega-3s supplementation in type 2 diabetes has no statistically significant effect on glycemic control or fasting insulin.
• 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.

Safety

• Omega-3 supplements usually do not have adverse effects. When they do occur, they typically consist of minor gastrointestinal symptoms, such as belching, indigestion, or diarrhea.
• Omega-3 supplements may extend bleeding time.

Diabetes is a group of chronic diseases that affect metabolism—the way the body uses food for energy and growth. Millions of people have diabetes, which can lead to serious health problems if it is not managed well. 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; however, there is currently not enough scientific evidence to suggest that any dietary supplements can help prevent or manage type 2 diabetes.

Here are 6 things you should know about taking dietary supplements for type 2 diabetes.

1. A healthy diet, physical activity, and blood glucose testing are the basic tools for managing type 2 diabetes. Your health care providers will help you learn to manage your diabetes and track how well you are controlling it. It is very important not to replace proven conventional medical treatment for diabetes with an unproven health product or practice.

2. Some dietary supplements may have side effects, including interacting with your diabetes treatment or increasing your risk of kidney problems. This is of particular concern because diabetes is the leading cause of chronic kidney disease and kidney failure in the United States. Supplement use should be monitored closely in patients who have or are at risk for kidney disease.

3. Chromium (an essential trace mineral found in many foods) has been studied for preventing diabetes and controlling glucose levels, but research has found it has few or no benefits. There have been a few reports of kidney damage, muscular problems, and skin reactions following large doses of chromium.

4. There is mixed evidence that magnesium helps to manage diabetes—benefits of magnesium supplements on diabetes have been found in some, but not all clinical studies. However, research suggests that people with lower magnesium intake may have a greater risk of developing diabetes. A large 2007 study found an association between a higher intake of cereal fiber and magnesium and a reduced risk of developing type 2 diabetes. Large doses of magnesium in supplements can cause diarrhea and abdominal cramping, and very large doses—more than 5,000 mg/day per day—can be deadly.

5. There is no strong evidence that herbs and other dietary supplements, including cinnamon, alpha-lipoic acid, and omega-3s, can help to control diabetes or its complications. Researchers have found some risks but no clear benefits of cinnamon for people with diabetes. For example, a 2012 review of the scientific literature did not support using cinnamon for type 1 or type 2 diabetes.

6. Talk with your health care provider before considering any dietary supplement for yourself, particularly if you are pregnant or nursing, or for a child. Do not replace scientifically proven treatments for diabetes with unproven health products or practices. The consequences of not following your prescribed medical regimen for diabetes can be very serious.