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5 Supplements People With Diabetes Should Avoid

Certain supplements like St. John’s wort, vitamin E, and niacin can affect glucose levels and may interact with certain medications. Here’s what you need to know.

When used correctly, dietary supplements can help bring the body into a state of balance by addressing specific nutrient and vitamin deficiencies. 

However, these benefits also come with risks, especially if you have diabetes and take supplements. 

“Individuals with diabetes should be cautious about consuming excessive amounts of certain vitamins through supplements, as they can potentially interfere with blood sugar levels,” said Barbara Kovalenko, a registered dietician and nutritionist.

Not only do some supplements have the potential to affect glucose levels, but they may also interact with diabetes medications. Here is a look at five supplements that people with diabetes should avoid. 

1. Vitamin E

Known for its antioxidant properties, vitamin E is a popular dietary supplement. Like most vitamins and minerals, obtaining vitamin E through natural sources like nuts and leafy greens is safe.

However, some should exercise caution when taking it in supplement form – especially people who take blood thinners like warfarin. Commonly prescribed to those with heart disease, which those with diabetes are 2-4 times more likely to develop, blood thinners help prevent blood clots from forming in the heart. 

Studies show that vitamin E interacts negatively with blood thinners by reducing the body’s ability to form clots even more, increasing the risk of bleeding. If you take any type of blood thinner, avoiding vitamin E supplements is wise.

2. St. John’s Wort

St. John's wort is an herbal supplement some people use as a mood stabilizer. It’s known to interact with several medications, including diabetes medications like sulfonylureas, thiazolidinediones, and DPP-4s (like Januvia), rendering them less effective and potentially leading to higher blood glucose levels. 

Similarly, those who take metformin should also avoid St. John’s wort, as some studies suggest that the supplement causes a build-up of metformin in the body. This build-up causes the body to release more insulin, which may affect glucose levels.

Finally, like vitamin E, avoid St. John’s wort if taking blood-thinning drugs as it may increase the risk of bleeding.

3. Ginseng

Ginseng is an herbal supplement that may improve symptoms of fatigue, reduce inflammation, and boost immunity. It may also lower fasting blood sugar levels and improve insulin sensitivity in those with type 2 diabetes, according to a review of studies on ginseng. 

While these findings are positive in theory, these effects may cause blood sugar levels to drop too low when taken with diabetes medications like insulin and metformin. Before supplementing with ginseng, speak with a healthcare provider and monitor your blood sugar closely. 

Keep a fast-acting sugar on standby in case you start experiencing symptoms of hypoglycemia (low blood sugar) like fast heartbeat, dizziness, or hunger.

4. Niacin

Also known as vitamin B3, niacin is sometimes used to raise HDL or “good” cholesterol levels and lower LDL or “bad” cholesterol levels. 

Studies show that niacin also raises glucose levels, making it a potentially dangerous supplement for those with diabetes. Like ginseng, discussing niacin with a healthcare provider is crucial to determine the appropriate dosage and whether supplementing with it is suitable.

5. Chromium

Chromium is a mineral found in whole grains, fruits, and vegetables. It may improve insulin sensitivity in people with type 2 diabetes, though research is largely inconclusive. More studies need to be done exploring how chromium supplementation may interact with common diabetes medications. 

The American Diabetes Association and the National Institute of Health suggest avoiding chromium if you take insulin, metformin, and other diabetes medications due to the increased risk of hypoglycemia.

Tips for choosing dietary supplements

When considering dietary supplements, especially if you have diabetes, it's crucial to take the following precautions:

  • Consult a healthcare provider: Always consult a healthcare professional before starting any new supplement. They can help you determine which supplements are safe and appropriate for your specific needs.

  • Beware of added sugar: Some supplements, particularly gummy vitamins or liquid formulations, may contain added sugars that can negatively impact blood sugar levels. Read labels carefully.

  • Eat nutrient-rich foods: Aim to get nutrients from unrefined whole foods rather than supplements. “It’s generally advisable to obtain essential nutrients from a balanced diet rather than relying on supplements unless directed otherwise by a healthcare provider,” Kovalenko said.

  • Monitor your blood glucose: Keep a close eye on your blood sugar when starting any new supplement to detect potential changes or adverse effects. Using a continuous glucose monitor (CGM) can help you keep track of your glucose levels around the clock.

As for what supplements people with diabetes can take? Kovalenko recommended omega-3s, which studies show have a beneficial effect for those with diabetes.

“Specific supplements like omega-3 fatty acids may help improve insulin sensitivity and reduce inflammation,” Kovalenko said.

The bottom line

While supplements can play a role in supporting overall health, people with diabetes should be cautious about the choices they make. It's also important to note that supplements and other herbal supplements should never replace medical treatment.

The five supplements mentioned above – vitamin E, St. John's wort, ginseng, niacin, and chromium – all have the potential to interfere with blood sugar control or interact with diabetes medicines. That said, other supplements may boost your health, like omega-3s, which get excellent reviews.

It's always best to consult with a healthcare provider and prioritize a balanced diet, regular physical activity, and other healthy lifestyle factors to manage blood sugar effectively and reduce the risk of diabetes complications like heart disease.

Learn more about diabetes management and other medications here: