Posted on 05/31/2026 9:10:15 PM PDT by SeekAndFind
Nearly 115 million Americans are on the road to diabetes. New research suggests an inexpensive, widely available supplement could slow that journey, but only for some of them.
A genetic quirk in roughly 70 percent of prediabetic adults may determine whether high-dose vitamin D can meaningfully lower their risk of developing Type 2 diabetes, according to a study published in JAMA Network Open.
The research builds on the D2d trial. More than 2,000 U.S. adults living with prediabetes were randomized to either take 4,000 units of vitamin D or a placebo for up to 3.5 years. Initially, the trial did not find any significant changes across the participants. The recommended daily allowance is 600 to 800 units for average adults.
However, when scientists analyzed participants’ DNA, a more nuanced picture emerged: those carrying specific variations—known as AC or CC—in a gene called ApaI responded strongly to supplementation. Over the 3.5 years of the study, participants carrying the AC or CC variant had a 19 percent lower chance of developing diabetes. The roughly 30 percent with the AA variation saw no benefit at all.
“Diabetes has so many serious complications that develop slowly over years,” study lead researcher Bess Dawson-Hughes said in a statement. “If we can delay the time a person spends living with diabetes, we can reduce some of those harmful side effects or lessen their severity.”
The distinction matters because prediabetes—defined by higher-than-normal blood sugar that hasn’t yet crossed into diabetes territory—affects more than two in five U.S. adults, and often progresses silently. Identifying who stands to benefit from vitamin D intervention could allow clinicians to target supplementation far more precisely than current blanket guidelines allow.
When vitamin D binds to cell receptors, it helps cells do what they are supposed to do. In pancreatic cells, vitamin D facilitates the release of insulin to regulate blood sugar.
People with the AC and CC variations were responsive to vitamin D and, therefore, derived more benefits from supplementation.
The findings could help develop a personalized approach to preventing Type 2 diabetes, senior author Anastassios Pittas, a professor at Tufts University School of Medicine, said in the statement. “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.”
However, researchers emphasized that more research is needed to determine which individuals might benefit from higher doses of vitamin D, with Dawson-Hughes noting that future testing could involve a simple, affordable genetic test to identify those most likely to benefit from supplementation.
“If your levels are found to be deficient, you may consider supplementation and review your dietary intake and sun exposure habits,” she said.
Cusa recommended that those who choose supplements should take 600 to 800 international units (IU) daily of vitamin D3 for general health. “Higher doses may be needed if a deficiency is noted or for any targeted prevention trials,” she added.
Current guidelines recommend 600 IU per day for people up to 70 years of age and 800 IU for those older than 70. Excessive vitamin D intake can be harmful and has been linked to increased risks of falls and fractures among older adults.
Sunlight, Cusa pointed out, is one of the most effective natural sources of vitamin D, and spending time outdoors can help boost your levels. “However, it’s important to be cautious—not to spend too long in the sun without proper sunscreen, as excessive exposure increases the risk of skin cancer,” she cautioned.
While you cannot overdose on vitamin D from sun exposure, she added, taking high-dose supplements can lead to toxicity, “so supplementation should be approached carefully and ideally under medical guidance.”
Natural sources of vitamin D include fatty fish such as salmon, tuna, mackerel, sardines, and rainbow trout. Other good sources are beef liver, mushrooms, egg yolks, and cod liver oil. “These foods, which are rich in protein and healthy fats, can help support stable blood glucose levels when consumed in moderation,” Cusa said.
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Thanks for posting. This caught my eye: “Excessive vitamin D intake can be harmful and has been linked to increased risks of falls and fractures among older adults.”
I’ve been taking 5,000 IU/Day since March 2020 (pandemic start). My Vit D blood level has been ranging 46 - 60.
We take 4,000 iu daily with K2 for the past 15 years plus a boatload of other supplements. We are pretty healthy.
I haven’t been taking K2. I pinged my doc about that over a week ago and haven’t heard from her.
yeah this article is weak sauce. no wonder they had no obvious effect at 4000 iu. that’s too low.
to have any effect you need to be supplementing in the 5000 to 10000 iu range continuously with K2 as a complement for the downside. this was from my frontline doctor’s advice. i think it’s since been confirmed in cancer studies.
when i caught the jab enhanced delta version of their bio-weapon, i had to overload for two weeks to get up to that maintenance dose. after that, i did very well and have since.
If you’ve done a DNA test... Go to DNA Portal... If you see the following under ‘Health Risk’... You’re likely heading towards Type 2 whether you like it or not.
Genotype: CT
Gene: SLC30A8
.
I think it’s safe to say everyone is different.
Sure - lowers diabetes risk by causing stomach pain, forcing you to eat less.
https://www.verywellhealth.com/supplements-that-are-bad-for-your-gut-11888010
Vit D supplement is best with food, along with K2 (MK7) to offset the major downside of D (sending calcium to arteries instead of bones). Then around 12 hours later, magnesium glycinate, when it helps you sleep and won’t interfere with vit D and K2.
If you can help it, buy from established brands and avoid supplements made in China (”sourced globally”). You’ll pay more for made in USA, but that’s another thing that helps you sleep!
That is a silly article. Most people can take any of those as supplements with zero stomach issues. And if you DO have stomach issues? Take less or stop. Very easy.
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