This Common Vitamin May Help Stop Prediabetes From Turning Into Diabetes

From scitechdaily.com 

Vitamin D may help prevent type 2 diabetes in people with specific genetic variations, offering a possible path toward personalized diabetes prevention

More than 40% of U.S. adults have prediabetes, a condition in which blood sugar levels are elevated but not yet high enough for a type 2 diabetes diagnosis. New research suggests vitamin D could help slow or prevent that progression in some people, depending on their genetics.

The study, published in JAMA Network Open, found that adults with prediabetes who carried certain variations of the vitamin D receptor gene had a 19% lower risk of developing diabetes when they took a high daily dose of vitamin D.

Researchers say the findings could eventually support more personalized approaches to diabetes prevention for the roughly 115 million Americans living with prediabetes.

The team examined data from the D2d study, a large multi-site clinical trial involving more than 2,000 U.S. adults with prediabetes. Participants received either 4,000 IU of vitamin D daily or a placebo to test whether supplementation could reduce diabetes risk.

Scientists have uncovered evidence that genetics may influence whether vitamin D can help prevent type 2 diabetes in people with prediabetes. Credit: Stock

Why the Original D2d Trial Raised New Questions

The original D2d trial did not show a significant drop in diabetes risk across all participants.

“But the D2d results raised an important question: Could vitamin D still benefit some people?” said Bess Dawson-Hughes, the study’s lead author and a senior scientist at the Jean Mayer USDA Human Nutrition Research Center on Aging at Tufts University.

“Diabetes has so many serious complications that develop slowly over years. If we can delay the time period that an individual will spend living with diabetes, we can stop some of those harmful side effects or lessen their severity.”

Earlier work from the D2d team found that participants with blood levels of 25-hydroxyvitamin D between 40 and 50 ng/mL or higher showed progressively greater reductions in diabetes risk.

Vitamin D Receptor Gene Variations Explained

Vitamin D in the bloodstream must first be converted into its active form before attaching to the vitamin D receptor, a protein that helps cells respond to the nutrient. Researchers suspected that genetic differences in this receptor could explain why vitamin D appeared to help some people but not others. Insulin-producing cells in the pancreas also contain vitamin D receptors, suggesting the vitamin may play a role in insulin release and blood sugar regulation.

For the new analysis, researchers examined genetic data from 2,098 trial participants who agreed to DNA testing. They compared people who appeared to benefit from vitamin D supplementation with those who did not, focusing on three common variations in the vitamin D receptor gene.

The results showed that adults with the AA variation of the ApaI vitamin D receptor gene, which accounted for about 30% of participants, did not benefit from high-dose vitamin D treatment compared with placebo. However, adults with the AC or CC variations experienced a significantly lower risk of developing diabetes when taking vitamin D.

Personalized Diabetes Prevention Potential

“The findings may represent an important step toward developing a personalized approach to lowering the risk of developing type 2 diabetes among high-risk adults,” said Anastassios Pittas, the study’s senior author, a professor of medicine at Tufts University School of Medicine, and chief of endocrinology, diabetes, and metabolism at Tufts Medical Center.

“Part of what makes vitamin D appealing as a potential preventive tool is that it is inexpensive, widely available, and easy for people to take.”

Researchers stressed that the findings should not encourage people to start taking high doses of vitamin D without medical advice. Current recommendations call for 600 IU daily for people ages 1 to 70 and 800 IU daily for adults older than 70.

High Vitamin D Risks and Future Genetic Screening

Too much vitamin D can be harmful and has been associated with a greater risk of falls and fractures in older adults. Scientists say more studies are needed to determine which individuals could safely benefit from higher doses.

“Our findings suggest we may eventually be able to identify which patients with prediabetes are most likely to benefit from additional vitamin D supplementation,” said Dawson-Hughes. “In principle, this could involve a single, relatively inexpensive genetic test.”

https://scitechdaily.com/this-common-vitamin-may-help-stop-prediabetes-from-turning-into-diabetes/

Vitamin D May Help Lower the Risk of Developing Type 2 Diabetes

From prevention.com

It's a little complicated, though

• New research suggests some people with prediabetes may benefit from a vitamin D supplement.
• The supplement can lower the risk of developing type 2 diabetes.
• There are a few things to consider before trying this.

More than 115 million Americans have prediabetes, which is when your blood sugar levels are higher than what’s considered a healthy range, but not quite at the level of a type 2 diabetes diagnosis. If you’re one of them, the big challenge is to do what you can to lower the risk your condition will progress to type 2 diabetes.

While eating healthy and being more active can cut your risk of developing type 2 diabetes in half when you have prediabetes, new research suggests that taking a high-dose vitamin D supplement may also help—but only for certain people with prediabetes.

The study, which was published in JAMA Network Open, analysed data from the D2d study, which was a large clinical trial that looked at the impact of 4,000 units of vitamin D a day vs. a placebo in more than 2,000 American adults with prediabetes to see if it would impact their progression to type 2 diabetes. (That particular study didn’t find benefits to taking vitamin D to prevent type 2 diabetes.)

In the latest study, researchers dove into genetic data from 2,098 people who participated in the trial. The researchers specifically compared the response to vitamin D supplement in people who had different common variations in the vitamin D receptor gene.

After crunching the data, the researchers discovered that with prediabetes who also had certain common variations in the vitamin D receptor gene had a 19% lower risk of developing type 2 diabetes when they took a high daily dose of vitamin D. (Those variations were AC or CC variations of the ApaI vitamin D receptor gene, if you want to get technical.)

While the findings don’t suggest that everyone with prediabetes should put themselves on a vitamin D supplement, the researchers note that it suggests genetic testing may be helpful in the future in identifying people with prediabetes who might benefit from higher doses of vitamin D.

But why vitamin D? Here’s the deal, according to experts.

                                                                                                                               mrs//Getty Images

This isn’t the only study to suggest vitamin D may help prevent type 2 diabetes

One study that was published in the Journal of the Endocrine Society in 2025 analysed data from 10 clinical trials that included nearly 4,500 people with prediabetes. The researchers found that 18.5% of the study participants who took vitamin D reached blood sugar levels that were normal, compared to the 14% of participants who took a placebo.

Another scientific analysis that was published in the Annals of Internal Medicinein 2023 analysed data from three clinical trials on the impact of vitamin D supplementation on people with prediabetes. After three years of follow-up, the researchers found that that 22.7% of participants who took vitamin D developed type 2 diabetes, while 25% of those who took a placebo did the same.

So far, the differences between people who took vitamin D or a placebo haven’t been massive—but they have been noticeable. The latest findings suggest that diving a little deeper into genetics may drive that impact even more.

What’s behind this?

There are likely a few things happening here. “The vitamin D receptor is the ‘sensor’ that allows the body to use vitamin D,” says Anastassios Pittas, M.D.,the study’s senior author, a professor of medicine at Tufts University School of Medicine, and chief of endocrinology, diabetes, and metabolism at Tufts Medical Center. “In some individuals, this receptor works more efficiently, so higher vitamin D levels can better support processes such as insulin function, leading to better glucose control.”

But in others, the receptor doesn’t respond as well. “So, taking more vitamin D may not have the same benefit,” Dr. Pittas says.

Vitamin D doesn’t act on its own, points out Scott Keatley, R.D., co-owner of Keatley Medical Nutrition Therapy. It binds to the vitamin D receptor, which then sparks a reaction in tissues like the pancreas beta cells, he explains. “Those cells are responsible for insulin secretion,” Keatley says. (Insulin is what your body uses to escort blood sugar into your cells, where it’s used for energy.) “If the receptor is slightly different due to genetic variation, the same vitamin D level can produce a different biological response,” Keatley says.

How can you know if vitamin D will help you?

There’s no quick and easy way to know if you have these genetic variations, according to Keri Gans, R.D.N., author of The Small Change Diet. “Right now, most people would not know,” she says. “This is based on a specific genetic variation, and that is not routinely tested for in standard care.”

However, you may notice some clues, according to Jessica Cording, R.D., the author of The Little Book of Game-Changers.

Cording suggests knowing what your vitamin D status is at baseline. “Blood work is very important, and this is a really easy test,” she says. “That will give you some clues as to if you're deficient and should supplement, along with how high of a dose.”

But follow-up blood work is especially crucial, per Cording. “That will help you see how your body responds to vitamin D and will give you clues to see whether you should continue or stop, or if you need a higher dose,” she says.

What is a ‘high dose’ of vitamin D?

It depends. “Traditionally, a ‘high’ dose has been defined as intake above 4,000 IU per day, which was set as the Tolerable Upper Intake Level by the Institute of Medicine in 2011,” Dr. Pittas says. “That said, thinking has evolved.”

Now, he says that healthcare providers imply think about what may be appropriate for each person, noting that this is often show in blood work. “In studies on type 2 diabetes prevention, greater benefit has been observed among individuals who achieve and maintain higher blood levels of 25-hydroxyvitamin D—around or above 40 ng/mL,” Dr. Pittas says. “Reaching these levels requires doses higher than 4,000 IU/day in some individuals.”

Do you need a vitamin D supplement?

If you have prediabetes, a vitamin D supplement is unlikely to be the way to avoid progressing to type 2 diabetes, whether you have this special genetic variant or not. “Diet and exercise are still the main drivers,” Keatley says. “When people with prediabetes improve diet quality, lose some weight, and move more, the reduction in diabetes risk is typically much larger and more consistent than what we see from any single nutrient.”

That doesn’t mean vitamin D is worthless, though. “Vitamin D, if it plays a role here, would likely be a smaller, supportive effect,” Keatley says. “Think of it as something that might fine-tune risk in certain people, not something that replaces the basics.”

Ultimately, if you have prediabetes and want to lower your risk of developing type 2 diabetes, it’s important to have a conversation with your healthcare provider about your treatment options.

Dietary supplements are products intended to supplement the diet. They are not medicines and are not intended to treat, diagnose, mitigate, prevent, or cure diseases. Be cautious about taking dietary supplements if you are pregnant or nursing. Also, be careful about giving supplements to a child, unless recommended by their healthcare provider.

https://www.prevention.com/health/health-conditions/a71110342/vitamin-d-protect-from-diabetes/ 

11 Supplements to Help Lower Blood Sugar Naturally

From verywellhealth.com

Some supplements like chromium, cinnamon, and omega-3s may help with blood sugar control or reduce diabetes-related risks. However, research is mixed, and some supplements can cause serious side effects, so always check with your healthcare provider before using them.

1. Alpha-Lipoic Acid

Alpha-lipoic acid is a fatty acid that acts as an antioxidant and has been studied for diabetes and its complications. However, the evidence is limited, and the research is mixed.

• One review found that alpha-lipoic acid did not lower blood sugar, triglycerides, or cholesterol in people with type 2 diabetes.
• Another review shows neuropathy (a symptom of diabetes) improved for participants taking the supplement, while other research didn't show improvement.
• There is no evidence that alpha-lipoic acid helps with nephropathy (kidney damage) or macular edema.

Safety

At normal doses, alpha-lipoic acid is considered safe, even for people with heart disease, diabetes, and neurological conditions. Side effects may include headache, nausea, and vomiting.

2. Cinnamon

In one study, cinnamon supplements lowered fasting blood sugar and insulin resistance in people with type 2 diabetes and prediabetes. However, more research is needed.

Other reviews show that cinnamon significantly reduced blood pressure, cholesterol, and triglyceride levels in people with type 2 diabetes.

Safety

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). Over time, too much coumarin can cause liver toxicity and cancer.

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

3. Magnesium

Higher levels of the mineral magnesium in the body are associated with a lower risk of diabetes. Magnesium lowers blood sugar in people with type 2 diabetes and improves insulin sensitivity in people at risk of developing diabetes. Magnesium supplements are available in many different formulations, but magnesium oxide has been studied the most extensively in clinical trials for diabetes.

Safety

Experts recommend limiting magnesium doses to 350 milligrams (mg) daily. You may get magnesium from your food, including fortified products like cereals. At higher doses, magnesium supplements are associated with diarrhoea, nausea, and stomach cramps.

4. Chromium

Chromium is a trace element in foods like meat, grains, and produce. It may enhance the effects of insulin and help break down sugars, but more research is needed.

One review concluded that chromium supplementation modestly improved haemoglobin A1c levels in people with type 2 diabetes. Chromium did not improve fasting blood sugar or cholesterol levels.

Safety

Chromium with insulin or metformin may cause hypoglycaemia (low blood sugar), so experts recommend that people taking these medications avoid chromium supplements. Signs of hypoglycaemia include shakiness, headache, and a fast heart rate. Side effects of chromium include weight loss, anaemia, kidney failure, and skin rash.

5. Zinc

Some research suggests that zinc may help protect against type 2 diabetes. A review of studies found that a moderately high intake of zinc was associated with a 13% reduction in the risk of type 2 diabetes. The effect was more pronounced for people living in rural areas, who experienced a 41% reduction in risk.

6. Vitamin D

Research shows that getting enough vitamin D may help prevent type 1 and type 2 diabetes. It also found that it may help reduce blood sugar in people with prediabetes.

Supplementing with vitamin D3 (cholecalciferol) 2,000 international units (IU) daily can help manage or prevent type 1 diabetes. Taking at least 1,000 IU daily for a year or more significantly lowered the odds of developing type 2 diabetes. Lower doses of vitamin D had no effect on diabetes risk.

Safety

The Recommended Dietary Allowance (RDA) of vitamin D for adults is 600 IU or 15 mcg. You can get vitamin D from fortified products like orange juice, cereals, and milk. You can also get adequate vitamin D from sun exposure. High doses of vitamin D from supplements may cause kidney stones, nausea, vomiting, muscle weakness, and more.

7. Omega-3 Fatty Acids

Research determined that omega-3 fatty acids help decrease blood sugar and insulin resistance. Other studies suggest that eating more omega-3 fatty acids helps protect against type 2 diabetes and may reduce blood sugar in people with prediabetes.

However, another review showed that omega-3 fatty acids had no significant effects on blood sugar or insulin resistance. Omega-3 fatty acids did improve levels of:

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

Safety

Omega-3 fatty acids don't typically cause severe side effects. However, high levels (over 4 g 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 also cause bad breath, heartburn, nausea, or diarrhoea. They may also increase the effects of blood-thinning medication and cause excess bleeding.

8. Berberine

Research shows that berberine may help control blood sugar in people with prediabetes. One review showed that berberine, with or without standard diabetes medicines, improved the following measurements related to diabetes control:

• Haemoglobin A1c
• Blood sugar two hours after eating (postprandial)
• Insulin resistance
• Body mass index (BMI)
• Total cholesterol
• Triglycerides
• Inflammation

Berberine plus standard diabetes medicine had greater effects, but even berberine alone showed modest benefits on haemoglobin A1c and fasting blood sugar levels.

Safety

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 diarrhoea.

9. Probiotics

In people with type 2 diabetes, a few studies have found that probiotics may help reduce:

Tao YW, Gu YL, Mao XQ, Zhang L, Pei YF. Effects of probiotics on type II diabetes mellitus: A meta-analysis. J Transl Med. 2020;18(1):30. doi:10.1186/s12967-020-02213-2.

• Haemoglobin A1C
• Fasting plasma glucose (FBG)
• Insulin resistance
  

10. Aloe Vera

A few studies have found that aloe vera supplements may reduce fasting blood sugar in people with prediabetes and type 2 diabetes. However, the research into this supplement is limited, and larger studies are needed to prove its effect conclusively.

11. Gymnema

Gymnema contains several pharmacologically active compounds, some of which may have anti-diabetic properties. However, more research is needed before scientists can understand how gymnema affects people with diabetes and how it can be used safely.

What Supplements Should a Diabetic Not Take?

Certain supplements can affect your blood sugar and/or interact with your medications. If you have diabetes, talk to your healthcare provider before taking: 

• Vitamin E: May interact with blood thinners such as Jantoven (warfarin)
• St. John's wort: May cause a build-up of metformin in the body and affect glucose levels
• Ginseng: May reduce blood sugar, but can cause a dangerous drop in blood sugar when taken with insulin or metformin
  

Key Takeaways

• Some supplements, such as cinnamon, berberine, and vitamin D, may help control blood sugar, but they should not replace prescribed diabetes medications.
• Other supplements, such as gymnema, aloe vera, and probiotics, have also positively impacted people with diabetes. However, more research is needed. Some supplements may interact with your medications. These include vitamin E, St. John's wort, and ginseng.

https://www.verywellhealth.com/supplements-for-diabetes-11771868 

"Dear Doctor: Can vitamin D help people with high-risk pre-diabetes avoid developing overt diabetes?"

From oregonlive.com/advice

By Dr. Keith Roach

DEAR DR. ROACH: I was diagnosed with prediabetes over 30 years ago. My parents had diabetes. I just turned 84, and my weight is 135 pounds. I am 5 feet and 3.5 inches tall.

I watch my diet and take four blood pressure pills, and my blood pressure is under control. My cholesterol is very low (my total cholesterol is 130 mg/dL) since I’ve been on 20 mg of simvastatin for over 30 years. I take berberine and other supplements to help keep my A1C level between 6.1% to 6.4%. I prefer not to add more medicine.

I also take bitter melon, alpha-lipoic acid, chromium, cinnamon, gymnema, and other supplements like vitamin D3, zinc and B12. What is your opinion? -- E.G.

ANSWER: It sounds like what you are doing is working since you haven’t developed diabetes. However, I can’t make any definitive statements on whether it’s one or more of your supplements that’s helping or whether it’s your healthy weight for your height.

Supplements are medicines. You are taking them, it seems, specifically to help prevent the development of diabetes. Of all the ones you mention, the one with the strongest evidence of benefit is vitamin D, which may help people with high-risk prediabetes prevent overt diabetes. The Endocrine Society recently published a guideline recommending it specifically for this purpose.

While I can find influencers and marketers who will tell you that these are all very helpful, the clinical trials on these tend to follow a pattern. Small trials suggest a large benefit, but larger and more rigorous studies show a much smaller benefit (or none). None of them are harmful in recommended doses, but I do think you may be wasting your money.

Good diet and exercise habits are probably the most critical for long-term prevention of diabetes. Getty Images Getty Images

You haven’t talked about your diet and exercise habits, which are probably the most critical for long-term prevention of diabetes. While 30 minutes of moderate exercise daily is a good rule of thumb for most people, if you want personalized information, you can talk to a diabetes educator or bring in a detailed food diary to a registered dietician/nutritionist. Both can help you sort out the truth from fiction and make recommendations. It’s a good investment.

https://www.oregonlive.com/advice/2025/07/dear-doctor-can-vitamin-d-help-people-with-high-risk-pre-diabetes-avoid-developing-overt-diabetes.html