Dietary Supplements for Diabetes
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 1.5 times more likely to use alternative
therapies than a person without diabetes. The appeal of a “natural” remedy that is easily
accessible without a prescription may lure you to seek alternative therapies to treat your
diabetes. This article will explain why you should think twice before making any
changes.
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 patient, your role is to:
 Promote an open dialogue with your doctors and other health care practitioners
 Ask questions about the use of dietary supplements
 Evaluate and discuss safety and efficacy issues
Consider these points:
 Manufacturers can market their products without scientific evidence that they are safe
 Scientific testing of most dietary supplements is limited
 The amount of active ingredients in products is not always consistent
 Supplements are sometimes sold without knowledge of how the active ingredients act
in the body
 The “more is better” mentality of many Americans should not apply to medicine or
medical care
 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 (GMPs), which provide some assurance
of a quality product
– Strict guidelines limit the health claims that companies can and cannot make
 Supplements often can interact with other supplements, over-the-counter medicines,
prescribed medicines, and even foods, creating adverse reactions and affecting
absorption; these interactions could make the supplement unsafe for an individual
 “Natural” is not synonymous with “safe” or “effective”
Individuals with diabetes always should tell their health care provider about any dietary
supplements that they are using or thinking about using, and not replace scientifically
proven treatments for diabetes with unproven alternative therapies. Serious consequences
can result from not following a medically prescribed regimen for diabetes. 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.
The following dietary supplements are some of the more commonly used for treatments
related to diabetes.
Aloe
 Intended actions:
– Improves glucose control
– Improves lipids
 Research findings:
– Two small, short-term studies showed improvements in fasting glucose and
triglyceride levels
– 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:
– Improves insulin sensitivity and glucose control
– Reduces symptoms of peripheral neuropathy (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 sugars
– 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 stomach upset
 Food sources:
– Liver
– Spinach
– Broccoli
– Potatoes
Bitter melon
 Intended actions:
– Improves glucose levels
 Research findings:
– Limited research has demonstrated decreases in fasting and other glucose levels
– Tablets and capsules not 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 sugar
– People with favism or glucose-6-phosphate dehydrogenase (G6PDH) deficiency
should understand the increased risk of hemolytic anemia
 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 were of poor quality
– Perhaps most promising is the combination of chromium picolinate with biotin, which
was recently 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
Cinnamon
 Intended actions:
– Decreases fasting blood sugar and lipid levels
– Increases insulin sensitivity
– Improves indigestion
 Research findings:
– Two clinical trials in patients with type 2 diabetes had conflicting results:
o In one small trial, daily consumption of 1, 3, or 6 grams (g) cinnamon for 6 weeks
led to lower fasting glucose and lipids following a meal
o A recent study found no such changes over a 3-month period when only a 1-g dose
was tested
– Notable differences between the two study populations may account for the differing
results
 Safety issues:
– No adverse reactions noted in moderate doses of 1–6 g/day
– May cause irritation when used topically
 Food sources:
– Not recommended that people attempt to consume therapeutic quantities of cinnamon
from foods, especially because many cinnamon-containing foods are high in sugar
and fat
Fenugreek
 Intended actions:
– Decreases blood sugar and lipids
 Research findings:
– Evidence is not strong, but 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
– 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 aftermeal 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
Gymnema
 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, high-density lipoprotein (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:
– A recent ConsumerLab report eases concerns regarding contamination of fish oil
supplements with mercury, pesticides, and polychlorinated biphenyls (PCBs)—all 50
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 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
– In two high-quality studies, 3 g/day of a margarine containing plant stanol esters was
shown to lower total cholesterol 11%–13% and LDL cholesterol 16%–20% without
changing HDL cholesterol
– 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 alphatocopherols, alpha-carotene, and beta-carotene
 Food sources:
– Vegetables
– Seeds
– Nuts
– Sterol- and stanol-fortified foods
Polyphenols
 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)
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
Academy of Nutrition and Dietetics. Evidence Analysis Library. Evidence summary:
effectiveness of stanols and sterols in hypercholesterolemic subjects receiving lipidlowering medications. Available to subscribers at: www.adaevidencelibrary.com.
Accessed June 11, 2012.
American Association of Clinical Endocrinologists. Medical Guidelines for the Clinical
Use of Dietary Supplements and Nutraceuticals. Available at:
https://www.aace.com/files/nutraceuticals-2003.pdf. Accessed June 11, 2012.
Blevins SM, Leyva MJ, Brown J, Wright J, Scofield RH, Aston CE. Effect of cinnamon
on glucose and lipid levels in non-insulin-dependent type 2 diabetes. Diabetes Care
[serial online]. 2007;30:2236-2237. Available at:
http://care.diabetesjournals.org/cgi/content/full/30/9/2236. Accessed June 11, 2012.
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.
National Center for Complementary and Alternative Medicine, National Institutes of
Health. Diabetes and CAM: a focus on dietary supplements. Available at:
http://nccam.nih.gov/health/diabetes/. Accessed June 11, 2012.
Stephens-Bogard K. Supplements commonly used by persons with diabetes. Nutritionists
in Complementary Care (Dietetic Practice Group of the American Dietetic Association,
fall newsletter). 2006;10:24-25.
Van Horn L, McCoin M, Kris-Etherton PM, et al. The evidence for dietary prevention
and treatment of cardiovascular disease. J Am Diet Assoc. 2008;108:287-331.
Review Date 6/12
D-0511