The Pros and Cons of Taking Supplements With Diabetes
Safety First: Supplements are unregulated by the Food and Drug Administration (FDA). For the safest products, look for the USP seal on the bottle. That means the supplement meets the standards of the United States Pharmacopeia. Can’t find it? Ask your pharmacist for help.
Whether you’re looking to hit your recommended daily allowance of vitamins and minerals or hoping to allay a complication of diabetes, there’s a world of supplements to consider—along with potential drug interactions, conflicting information, and safety issues.
That’s why it’s important to do a full medication review with your doctor or pharmacist before you start taking any supplement. Those experts can help you avoid harmful interactions with your medications, says Nicole Pezzino, PharmD, BCACP, CDE, assistant professor in the Department of Pharmacy Practice at Wilkes University in Wilkes-Barre, Pennsylvania.
Before you buy, know that the research is mixed when it comes to vitamins and supplements for people with diabetes. According to the American Diabetes Association’s 2018 Standards of Medical Care in Diabetes, “There is no clear evidence that dietary supplementation with vitamins, minerals, herbs, or spices can improve outcomes in people with diabetes who do not have underlying deficiencies, and there may be safety concerns regarding the long-term use of antioxidant supplements such as vitamins E and C and carotene.”
Whether or not a supplement has clinical evidence to suggest it helps with diabetes or related complications, the bigger question to ask is: Are you going to be harmed by taking this supplement or vitamin?
So you’re not a fan of vegetables. Why not just pop a pill that contains the same vitamins and minerals? According to Toby Smithson, MS, RDN, LD, CDE, a spokesperson for the American Association of Diabetes Educators, vitamins and minerals are best absorbed through food.
Think of it like this: Whole foods contain a mix of minerals, enzymes, fiber, and other substances that may help your body absorb and use these nutrients. Eating a well-balanced meal is much healthier than a multivitamin. Whether isolated vitamins and minerals have the same effect in the body when taken in supplement form is less clear.
If you have a true deficiency, however, a supplement may be helpful. Americans are most commonly deficient in vitamins D and B12, calcium, and iron. The only way to know whether you’re deficient is through blood work, says Smithson, but you might see some clues. For instance, fatigue can be a sign you’re deficient in vitamins D or B12.
Supplements may cause undesirable—or dangerous—side effects, especially if they interact with your meds. While some ingredients could amplify the effects of your diabetes drugs, causing low blood glucose (hypoglycemia), others may have the opposite effect, leading to elevated blood glucose.
Complicating matters: Research on many supplements is fairly inconclusive. Talk to your doctor or pharmacist before you start taking chromium, vitamin E, St.-John’s-wort, glucosamine, or niacin.
Some research suggests that a chromium deficiency may lead to high blood glucose levels. An analysis of studies published last year in the journal Molecular Nutrition and Food Research found that chromium supplements in people with type 2 might be worthwhile alongside prescribed diabetes medications—but the evidence is thin. Pezzino says it may be worth a try if you’re deficient in chromium, but that’s very rare. Steer clear if you’ve been diagnosed with kidney disease. Chromium supplements might further damage the kidneys and worsen the disease.
- VITAMIN E & ST.-JOHN’S-WORT
Both vitamin E and the herb St.-John’s-wort can have dangerous interactions with blood-thinning drugs used to treat heart disease and can thereby increase your bleeding risk, says Pezzino. A study published in 2013 in the Journal of the American Heart Association found that, among people with heart disease who were being treated with the blood thinner warfarin, those most likely to experience bleeding events had higher levels of vitamin E in their bodies. Other studies have found that St.-John’s-wort amplifies the effect of blood thinners. Final verdict? Avoid these supplements if you’re taking a blood-thinning medication. Besides warfarin, those include apixaban, dabigatran, heparin, and rivaroxaban.
People take glucosamine—a natural compound found in healthy cartilage—in hopes of lessening arthritis pain and improving joint mobility. Early research raised questions about whether glucosamine contributes to insulin resistance, but findings were inconclusive. More recent research found no association with insulin resistance or increased blood glucose in people with diabetes, but it didn’t totally rule out the possibility. A better reason to question the supplement: There’s not much proof it’s useful for joint health or joint pain.
Some people take niacin to raise HDL (“good”) cholesterol, but it can also affect your diabetes management, says Pezzino. A 2016 study published in The American Journal of Medicine found that niacin raised fasting glucose levels in study participants, meaning the risks may outweigh the benefits. What’s more, while niacin can raise HDL cholesterol, there’s no evidence that this leads to a lower risk of cardiovascular disease, and niacin can have harmful side effects. A chat with your health care provider can help you determine if this is safe for you to take.
Confused about what to take? Unless your doctor or pharmacist recommends a specific vitamin or supplement, it’s probably not all that helpful—or economical—to add another pill to your regimen. “There are a lot of supplements that have a small amount of evidence” to substantiate the claims about them, says Donald Hensrud, MD, MPH, a public health and general preventive medicine specialist at the Mayo Clinic in Rochester, Minnesota. “That doesn’t translate into clinical benefit.”
What to know about some other common supplements
1. A B12 supplement can be helpful if you have type 2 diabetes and are deficient in the vitamin.
A 2012 study published in Diabetes Care found that people taking metformin for type 2 diabetes had lower levels of vitamin B12. “People over the age of 65 are already at an increased risk of B12 deficiency,” says Donald Hensrud, MD, MPH, a public health and general preventive medicine specialist at the Mayo Clinic in Rochester, Minnesota. If you’re on metformin, talk to your doctor about periodically being tested for a B12 deficiency. One clue you could be deficient: You’re experiencing neuropathy-like pain, says Rick Hess, PharmD, associate professor of pharmacy practice at the Bill Gatton College of Pharmacy at East Tennessee State University in Johnson City, Tennessee. “In that case, if you [take] a B12 vitamin, the symptoms improve.” (The vitamin won’t help if you have neuropathy that’s unrelated to a B12 deficiency, though.)
2. Vitamin C and E supplements won’t ward off diabetes and diabetes complications.
“[Researchers] have looked at using antioxidants such as vitamins C and E and beta-carotene for diabetes, but overall there has been little benefit,” says Hensrud. Until the research shows a clear benefit, it’s best to pass on these.
3. The jury’s still out on vitamin D.
Recent research has raised the question of whether vitamin D may prevent diabetes. In a study published in 2017 in the journal Diabetes, for instance, researchers found an association between higher concentrations of vitamin D in the blood in childhood and a lower risk of type 1 diabetes. More research is needed to understand the link, but here’s one thing experts can agree on: If you’re deficient in vitamin D, a supplement can help.
4. Cinnamon isn’t as effective as your type 2 diabetes medication.
A study published in a 2012 issue of Clinical Nutrition showed that consuming between 1 and 6 grams of cinnamon per day can modestly lower fasting blood glucose. But research published in 2016 in the Journal of the Academy of Nutrition and Dietetics found that the supplements did nothing to help people with type 2 achieve treatment goals or provide a reliable drop in blood glucose. Bottom line: Enjoy a sprinkling of cinnamon on oatmeal, but skip cinnamon supplements.
5. Alpha-lipoic acid (ALA) reduces pain from diabetic neuropathy.
A review of studies published in 2012 in the International Journal of Endocrinology examined the use of ALA on diabetic neuropathy (nerve damage). Researchers concluded that ALA injections, which are available only in Europe, improve symptoms of neuropathy in the short term. Results were mixed with oral supplements, which are available in the United States. Regardless, Hess routinely suggests ALA pills for people with diabetic neuropathy. “I don’t hesitate to recommend 600 milligrams a day to help people relieve pain,” he says. Keep in mind: It doesn’t always work, and allergic skin conditions have been reported in rare instances.