Diet and Nutrition

An Update on Dietary Supplements for Diabetes Care

April 25, 2017   /

Americans spend billions of dollars on dietary supplements every year. Adults report taking supplements for many reasons:

  • To promote weight loss
  • As insurance for an inadequate diet
  • To increase their energy level
  • To prevent or treat diseases, including diabetes

It is estimated that people with diabetes are 1.6 times more likely to use complementary or alternative therapies than a person without diabetes. The appeal of a “natural” remedy that is easily accessible without a prescription may lure you into seeking alternative therapies to treat your diabetes. This article will explain why you should think twice and ask questions before you start to take dietary supplements to manage your diabetes.

Dietary supplements are defined by the Dietary Supplement Health and Education Act (DSHEA) of 1994 as products taken orally that contain dietary ingredients intended to supplement the diet, including vitamins, minerals, herbs, botanicals, amino acids, enzymes, organ tissues, glandular substances, and metabolites.

As an informed person with diabetes, your role is to:

  • Promote an open dialogue with your health care providers
  • Ask questions about the use of the dietary supplements you use or are considering using
  • Evaluate and discuss safety and efficacy issues

Consider these points:

  • Current laws allow manufacturers to market dietary supplements without scientific evidence that they are safe
  • Scientific testing of most dietary supplements is limited
  • Because of manufacturing procedures, the amount of active ingredients in supplements may be inconsistent
  • Supplements are sometimes sold without knowledge of how the active ingredients act in the body
  • The “more is better” mentality should not apply to supplements
  • Supplements are regulated as foods, not drugs, meaning they are not held to the same level of safety and efficacy testing as pharmaceutical products:
    • Dietary supplement companies must demonstrate adherence with quality assurance programs and good manufacturing practices, which provide some assurance of a quality product
    • Strict guidelines limit the health claims that companies can and cannot make
  • Supplements often interact with other supplements, over-the-counter medicines, prescribed medicines, and even foods. These interactions can create adverse reactions and/or affect absorption. These interactions could make the supplement unsafe for the users
  • “Natural” is not synonymous with “safe” or “effective”

If you take supplements you  should make sure your health care provider is aware of what and how much you take. Also, it’s best to not replace scientifically proven treatments for diabetes with unproven alternative therapies. In addition, use of a dietary supplement may require an adjustment in prescribed medicines for diabetes and other major health conditions. It is especially important for people with diabetes who also use dietary supplements to closely monitor their blood glucose levels as some supplements can decrease or increase glucose levels.

The following dietary supplements are the more common ones suggested for and/or used by people with diabetes.


  • Intended actions:
    • Improves glucose control
    • Improves lipids
  • Research findings:
    • Two small, short-term studies showed improvements in fasting glucose and triglyceride levels, but other studies show mixed results
    • Insufficient evidence to make recommendations
  • Safety issues:
    • Can have a strong laxative effect
    • May prolong surgical bleeding times
  • Food sources:
    • The leaves of the aloe plant
    • Products made from aloe gel or dried aloe leaves


Alpha-lipoic acid (ALA)

  • Intended actions:
    • Helps your insulin to work better
    • May reduce symptoms of neuropathy (nerve pain in hands and feet)
  • Research findings:
    • Small studies in animals and humans have demonstrated limited benefit
    • More well-controlled studies needed to better understand benefits and action before recommending use
  • Safety issues:
    • May cause low blood glucose levels
    • May reduce blood levels of minerals, such as iron
    • May interact with some medicines, such as antacids
    • May decrease the effectiveness of some anticancer drugs
    • May cause other side effects, including headache, skin rash, and upset stomach
    • Avoid with thiamine deficiency, alcoholism, pregnancy, or lactation
  • Food sources:
    • Liver
    • Spinach
    • Broccoli
    • Potatoes

Bitter melon

  • Intended actions:
    • Improves blood glucose levels
  • Research findings:
    • Limited research has demonstrated decreases in fasting and other glucose levels
    • Tablets and capsules have not been tested in clinical studies
    • More research needed before recommending use
  • Safety issues:
    • Not recommended for pregnant women or women who may become pregnant (may cause miscarriages)
    • Not recommended for children
    • Not recommended for nursing women
    • Not recommended for individuals with allergies to foods in the melon family
    • Can cause hypoglycemia, when used in combination with medications that lower blood glucose
    • Not recommended for those with a glucose-6-phosphate dehydrogenase (G6PDH) deficiency
  • Food sources:
    • The fruit and seeds of bitter melon (related to honeydew and cantaloupe melons)

Chromium picolinate

  • Intended actions:
    • Improves blood sugar levels
  • Research findings:
    • A significant Chinese study showed improvements in fasting blood sugar and A1c after 4 months
    • Several other studies have shown positive results, but those studies were of poor quality
    • Perhaps most promising is the combination of chromium picolinate with biotin, which was shown to improve glucose levels and A1c in a study of almost 350 patients with type 2 diabetes
    • Still too soon to give specific recommendations
  • Safety issues:
    • Probably safe for adults at low doses, except for the possibility of low blood sugar
    • May cause kidney problems at high doses
  • Food sources:
    • Meats
    • Animal fats
    • Fish
    • Coffee
    • Tea
    • Whole grains
    • Brewer’s yeast
    • Broccoli
    • Nuts
    • Egg yolks
    • Some spices
    • Some beers and wines


  • Intended actions:
    • Decreases fasting blood sugar and lipid levels
    • Increases insulin sensitivity
    • Improves indigestion and has been shown to delay gastric emptying
  • Research findings:

Several studies have shown improvement in fasting glucose or A1C, and in a review of 10 research studies, scientists determined that subjects with type 2 diabetes who took cinnamon along with their regular diabetes medications experienced lower fasting glucose, total cholesterol, and  triglycerides, and increased high-density lipoprotein (HDL)-cholesterol (good cholesterol) compared with control groups.(Allen et al.) The cinnamon doses ranged from 120 mg/day to as much as 6 g/day for 4 to 18 weeks. One teaspoon of powdered cinnamon is about 4 grams.

  • Safety issues:
    • No adverse reactions noted in moderate doses of 1 to 6 g/day
    • No liver toxicity has been noted, but studies on kidney function from long-term use are controversial
    • May cause irritation when used topically
    • Food sources:
    • Powdered cinnamon


  • Intended actions:
    • Decreases blood sugar by stimulating insulin receptors and increasing glucose uptake
  • Research findings:
    • Evidence is not strong, but it does support the use of fenugreek with meals for decreasing blood sugar and lipid values
    • Optimal dosage not yet determined
  • Safety issues:
    • May cause mild gastrointestinal distress
    • May cause hypoglycemia, especially if used with glucose-lowering medications
    • Elevated potassium, dizziness, and urinary frequency has been noted in healthy men
    • Potential allergen in the peanut/soybean family
    • Avoid during pregnancy, because fenugreek may cause uterine contractions
    • May appear in breast milk
  • Food sources:
    • Seeds from the fenugreek plant are used in supplements
    • Seeds pulverized into powder are mixed into foods

Ginseng (Asian and American)

  • Intended actions:
    • Active ingredient—ginsenosides

– Improves glucose levels following meals

  • Improves A1C
  • Research findings:
    • Good evidence exists showing that ginseng is possibly effective in lowering after-meal blood sugar levels and A1C
    • Usual dose of Asian ginseng is 200 milligrams (mg)/day; usual dose of American ginseng is 3 g before a meal
  • Safety issues:
    • May cause insomnia
    • May cause anxiety
    • May cause headache
    • May cause increased blood pressure
    • Past problems with standardizing ginseng supplements
    • Multiple interactions with drugs
    • Potential allergen
  • Food sources:
    • The root of the ginseng plant is the part used medicinally


  • Intended actions:
    • Decreases blood sugar and lipid levels
  • Research findings:
    • Patients with both type 1 and type 2 diabetes were able to decrease their medication requirements following use of gymnema
    • Decreases shown in fasting blood sugar, A1C, and lipid levels
    • Usual dose is 400 mg/day
  • Safety issues:
    • May cause low blood sugars, especially when used in combination with medications for diabetes
  • Food sources:
    • Not applicable
    • The leaves of the Gymnema sylvestre plant are used medicinally


Omega-3 fatty acids

  • Intended actions:
    • Reduces triglyceride level
    • Reduces inflammation
    • Reduces risk of heart disease
  • Research findings:
    • Research of fish oil supplementation in people specifically with type 2 diabetes has confirmed reduction in triglyceride levels but no significant effect on low-density lipoprotein (LDL) cholesterol, HDL cholesterol, total cholesterol, fasting blood sugar, or A1C
    • In some study populations, LDL levels actually increased significantly, while triglycerides decreased, so it is important to obtain an individualized recommendation for use of omega-3s from a registered dietitian or other qualified health care professional
  • Safety issues:
    • Verify the safety and quality of your supplement with an independent testing lab such as In 2016, almost all omega-3 products tested met label claims with regard to eicosapentaenoic acid (EPA) and docosahexaenoic acid (DHA) concentrations, and were free of contaminants
    • High doses of fish oil can interact with certain medications, such as anticoagulants and blood pressure drugs
    • Possible side effects include a fishy aftertaste, belching, stomach disturbances, and nausea; avoid this by purchasing enteric-coated pills
    • The usual dose for lowering triglycerides is 1 g/day total EPA and/or DHA
  • Food sources:
    • Fish
    • Fish oil
    • Some vegetable oils (primarily canola and soybean)
    • Flaxseed
    • Walnuts
    • Wheat germ

Phytosterols or plant stanol/sterol esters

  • Intended actions:
    • Decreases total and low-density lipoprotein (LDL) cholesterol
  • Research findings:
    • Evidence is sufficient to promote the use of plant sterols and stanols for reducing total and LDL cholesterol levels in people at increased risk for coronary heart disease
    • The effects were similar in patients who were and were not taking statin drugs to lower cholesterol
    • Plant sterols are most effective when they are present in the intestine simultaneously with cholesterol
  • Safety issues:
    • Phytosterols are well tolerated
    • Higher levels of phytosterol consumption may result in reduced absorption of alpha-tocopherols, alpha-carotene, and beta-carotene
  • Food sources:
    • Vegetables
    • Seeds
    • Nuts
    • Sterol- and stanol-fortified foods


  • Intended actions:
    • Promotes vascular health because of the antioxidant properties
    • Decreases cholesterol
    • Decreases blood pressure
    • Improves insulin utilization
  • Research findings:
    • Limited clinical research suggests a benefit of lower blood pressure from eating dark chocolate in some populations, but further studies are needed to determine dosages and other parameters
    • Support for the cardiovascular benefits of green tea are based primarily on laboratory studies; the few small clinical trials with green tea did not show significant effects
  • Safety issues:
    • None known from the polyphenols themselves, but many of the food sources of polyphenols contain caffeine, which is problematic for some people, especially at higher quantities
  • Food sources:
    • Green tea
    • Dark chocolate (high cocoa content)
    • Grapes, wine, peanuts, berries

Prickly pear (nopal)

  • Intended actions:
    • Decreases glucose levels
  • Research findings:
    • Limited research is available showing the effectiveness of prickly pear in reducing blood sugar, when consumed as part of a meal or as a dietary supplement
    • The effect is additive when combined with blood sugar-lowering drugs
    • Most of the research has used prickly pear in food form
    • No specific recommendations are given at this time
  • Safety issues:
    • Increases stool volume
    • May cause diarrhea
  • Food sources:
    • A type of cactus often consumed in Hispanic cultures


References and recommended readings

1. Dietary Guidelines for American: 2015-2010, Eighth Edition. Accessed April 25, 2017.

2. Academy of Nutrition and Dietetics. Evidence summary: effectiveness of stanols and sterols in hypercholesterolemic subjects receiving lipid-lowering medications. Evidence Analysis Library website. Available to subscribers at: Accessed March 21, 2017.

3. Allen RW, Schwartzman E, Baker WL, Coleman CI, Phung OJ. Cinnamon use in type 2 diabetes: an updated systematic review and meta-analysis. Ann Fam Med. 2013;11(5):452-459.

4. American Association of Clinical Endocrinologists. Medical Guidelines for the Clinical Use of Dietary Supplements and Nutraceuticals. Available at: Accessed April 25, 2017.

5. Benefits of select herbs and spices for glucose control. Dietitians in Integrative and Functional Medicine website. Published September 2015. Available to members only.

6. FDA 101: Dietary Supplements. Accessed April 21, 2017.

7. Geil P, Shane-McWhorter L. Dietary supplements in the management of diabetes: potential risks and benefits. J Am Diet Assoc. 2008;108(4 Suppl 1):S59-S65.

8. Medagama AB, Bandara R. The use of complementary and alternative medicines (CAMs) in the treatment of diabetes mellitus: is continued use safe and effective? Nutr J 2014;13(1):102.

9. National Center for Complementary and Alternative Medicine, National Institutes of Health. Diabetes and Dietary Supplements: In Depth website. Accessed April 25, 2017.

10. Natural Medicines Database. Diabetes. Available to subscribers at Accessed April 25, 2017.

Review Date October 13, 2016

Updated by staff