Supplements for Diabetes

Many people use dietary supplements like cinnamon, magnesium, or vitamin D to help prevent or manage diabetes, a disease marked by high blood sugar levels.

Research has primarily focused on the effects of dietary supplements in people with type 2 diabetes. This type of diabetes occurs over time as the body becomes resistant to insulin, which, simply put, is a hormone that helps convert food into energy.

There is less data about the benefits of supplements for those with type 1 diabetes, an autoimmune disorder that happens when the pancreas doesn't make enough insulin.

Here's what you need to know about dietary supplements' effectiveness and side effects that may help lower blood sugar.

Important Nutrients for Diabetes

Keep in mind that the American Diabetes Association does not recommend the use of dietary supplements to manage or prevent diabetes. Supplements have not been proven to consistently lower blood sugar. The suggested approach for managing diabetes is more holistic, using the following:

• A balanced diet (e.g., adequate fiber, nonstarchy vegetables, and adequate protein)
• Movement (at least 150 minutes per week)
• Medication (if needed)
• Maintain a 7% weight reduction (for type 2 diabetes)

With that in mind, here's the latest evidence about the uses and side effects of supplements often touted for diabetes.

Alpha-Lipoic Acid

Alpha-lipoic acid is a fatty acid that acts as an antioxidant. It has been studied for diabetes and its complications, such as:

• Neuropathy (nerve pain)
• Nephropathy (kidney damage)
• Macular edema (blood vessels leak into the eye's retina)

But so far, there's little evidence it helps.

An extensive review of 10 studies concluded that alpha-lipoic acid did not lower the following in people with type 2 diabetes any more than a placebo (sugar pill):

• Blood sugar
• Triglycerides (fats in the blood)
• Cholesterol

A clinical trial of people with type 1 diabetes found no difference in hemoglobin A1c (a measurement of blood sugar control over the past few months) from alpha-lipoic acid vs. a placebo.

The evidence of alpha-lipoic acid's effects on neuropathy is mixed.

A systematic review reported that three of eight trials studied showed symptom improvement for those taking the supplement, while the other five trials didn't show improvement.

There is no evidence that alpha-lipoic acid helps with nephropathy or macular edema.

Safety and Precautions

At normal doses, alpha-lipoic acid is considered safe, even for people with heart disease, diabetes, and neurological conditions.

Side effects that may occur with this supplement include the following:

• Headache
• Nausea
• Vomiting

Chromium

Chromium is a trace element found in foods like meat, grains, and produce.

It may enhance the effects of insulin and help break down sugars, but more research is needed to know for sure.

The evidence for chromium's effects on diabetes is mixed.

One review of 10 studies concluded that chromium supplementation modestly improved hemoglobin A1c levels in people with type 2 diabetes.

Chromium did not improve fasting blood sugar or cholesterol levels.

Safety and Precautions

AIs for chromium in adults are 25 micrograms (mcg) per day in females and 35 mcg in females. AIs drop to 30 mcg during pregnancy but increase to 45 mcg during breastfeeding.

Taking chromium with insulin or metformin together may cause hypoglycemia (low blood sugar).

Watch for signs of hypoglycemia, such as the following:

• Shakiness
• Headache
• Fast heart rate

Chromium may also cause the following side effects, according to case reports:

• Weight loss
• Anemia
• Liver dysfunction
• Kidney failure
• Skin rash

Cinnamon

The popular spice cinnamon has been studied in people with prediabetes and type 2 diabetes for its effects on:

• Blood sugar
• Cholesterol
• Blood pressure

According to an analysis of 16 clinical trials, cinnamon supplements lowered fasting blood sugar and insulin resistance in people with type 2 diabetes and prediabetes (high blood sugar levels not high enough to be considered type 2 diabetes).

However, researchers noted that more robust trials are needed because the existing ones have a lot of variability.

Other extensive reviews have shown that cinnamon significantly reduced blood pressure and cholesterol levels in people with type 2 diabetes, including:

• Total cholesterol
• Triglycerides
• Low-density lipoprotein (LDL) cholesterol (considered "bad")

More research is needed to determine the effects of cinnamon in people with type 1 diabetes.

Safety and Precautions

Cinnamon is safe for most people at doses below 6 grams (g) daily.

However, there have been reports of high coumarin levels in species like cassia cinnamon (Cinnamomum cassia). Adverse effects of too much coumarin over time can include the following:

• Liver toxicity
• Cancer

True cinnamon (Cinnamomum verum), also known as Ceylon or Sri Lankan Cinnamon, tends to have lower levels of coumarin.

Other effects to be aware of include:

• Liver disease
• Skin rash (hypersensitivity reaction)
• Gingivitis

Magnesium

Higher levels of the mineral magnesium in the body are associated with a lower risk of diabetes.

Magnesium lowered blood sugar in people with type 2 diabetes, according to a large systematic review of clinical trials.

It also improved insulin sensitivity in people at risk of developing diabetes. Conditions that increase type 2 diabetes risk include the following:

• Being overweight
• Polycystic ovary syndrome (PCOS)
• Metabolic syndrome
• Prediabetes

Magnesium supplements are available in lots of different formulations, but magnesium oxide has been studied the most in clinical trials for diabetes.

Safety and Precautions

The RDA for magnesium in adults is 310 mg for females and 400 mg for males. This amount increases slightly as you age. Limit magnesium doses to 350 milligrams (mg) daily.

You may be getting magnesium from your food, including fortified products like cereals.

At higher doses, magnesium supplements are associated with the following common side effects:

• Diarrhea
• Nausea
• Stomach cramps

Daily doses of more than 5,000 mg may cause toxicity. Watch for warning signs like the following:

• Low blood pressure (hypotension)
• Vomiting
• Fatigue
• Flushing

Omega-3 Fatty Acids

The evidence for using omega-3 fatty acids for diabetes is mixed.

One review of 30 studies determined that omega-3 fatty acids helped decrease blood sugar and insulin resistance (when cells don't respond well to insulin, can't easily take up glucose from the blood, and require more insulin).

Results from another, smaller review suggest that eating more omega-3 fatty acids helped protect against type 2 diabetes.

On the other hand, an analysis of 46 clinical trials showed that omega-3 fatty acids had no significant effects on blood sugar or insulin resistance.

In people with type 2 diabetes, omega-3 fatty acids did improve levels of the following:

• Hemoglobin A1c
• Total cholesterol
• High-density lipoprotein (HDL) cholesterol (considered "good")
• Triglycerides

Safety and Precautions

Adequate Intakes (AIs) for omega-3s in adults are 1.6 g for males and 1.1 g for females, slightly increasing during pregnancy. If you regularly eat fish or nuts, you may get adequate omega-3s. Omega-3s can also be found in fortified foods like eggs, yogurt and milk, juices, cereals, and more.

Omega-3 fatty acids don't typically cause severe side effects. However, high levels (over four grams per day) of omega-3s have modestly increased the risk of atrial fibrillation in people with, or at risk for, cardiovascular disease.

Omega-3s may cause mild gastrointestinal effects like the following:

• Bad breath
• Heartburn
• Nausea
• Diarrhea

Berberine

Berberine is an herb used in traditional Chinese medicine and Ayurvedic medicine (the ancient medicine system of India) to help lower blood sugar and cholesterol in people with type 2 diabetes.

A review of 46 clinical trials demonstrated that berberine, with or without standard diabetes medicines, improved the following measurements related to diabetes control:

• Hemoglobin A1c
• Blood sugar two hours after eating (postprandial)
• Insulin resistance
• Body mass index (BMI), a commonly used health metric despite its limitations
• Total cholesterol
• Triglycerides
• Inflammation

Effects were greater for berberine plus standard diabetes medicine, but even berberine alone showed modest benefits on hemoglobin A1c and fasting blood sugar levels.

Safety and Precautions

Berberine should be avoided during pregnancy and breastfeeding as it may cause jaundice or brain damage in infants who are exposed to it.

Side effects of berberine include constipation and diarrhea.

Vitamin D

Vitamin D is made in the body from sunlight's ultraviolet rays.

Research shows that getting enough vitamin D may help prevent both type 1 and type 2 diabetes.

Supplementing with vitamin D3 (cholecalciferol) 2,000 international units (IU) daily can be helpful in managing or preventing type 1 diabetes.

Taking at least 1,000 IU daily for a year or more significantly lowered the odds of developing type 2 diabetes, according to a review of nine clinical trials.

Interestingly, lower doses of vitamin D had no effect on diabetes risk.

Safety and Precautions

The normal Recommended Dietary Allowance (RDA) of vitamin D for adults is 600 IU or 15 mcg.

You may be getting additional vitamin D from your food, including special fortified products like:

• Orange juice
• Cereals
• Milk

You can also get adequate vitamin D from sun exposure. However, the following factors can make getting enough vitamin D from sunlight challenging:

• Living at higher latitudes
• Fall and winter months in cold climates
• Living in cloudy climates
• Having darker skin

Supplementation is a viable option in these cases.

However, note that high doses of vitamin D from supplements can cause the following side effects:

• Kidney stones
• Nausea
• Vomiting
• Muscle weakness
• Kidney failure
• Hypervitaminosis D (vitamin D toxicity)

Discuss plans to supplement with your healthcare provider or RDN.

About Diabetes

About 11% of people in the United States have diabetes, a disease characterized by high blood sugar.

If it's not well controlled, diabetes can decrease quality of life and cause serious complications, including the following:

• Blindness
• Kidney failure
• Amputations
• Heart problems

Typically, management involves both lifestyle modifications (like exercise and a healthy diet) and medications (like insulin or other prescription medications).

Some dietary supplements may cause kidney damage, which people with diabetes are particularly susceptible to. If you have kidney disease, be especially careful about using supplements to help manage your blood sugar.

Ultimately, a supplement is not a good substitute for diabetes medications that are proven to be safe and effective.

If you have diabetes or are trying to prevent it, it's important to discuss the use of any supplement with your healthcare provider in order to optimize your health goals.

Summary

So far, there's some evidence that dietary supplements like cinnamon, berberine, and vitamin D may improve blood sugar control in people with diabetes. These are not substitutes for FDA-approved diabetes medications, though.

A healthy diet is essential in preventing and managing diabetes and its complications. A low-fat, high-fiber diet like the Mediterranean diet can help prevent type 2 diabetes.

Low-carbohydrate and vegan diets have also modestly improved blood sugar levels.