More Than Half of People with Diabetes Are Deficient in This Vitamin, New Study Suggests

Reviewed by Dietitian Annie Nguyen, M.A., RD

More than 38 million Americans have diabetes, and between 90% and 95% of them have type 2 diabetes. While most are adults over the age of 45, an increasing number of children and teens are also developing the condition. The good news is that most type 2 diabetes cases can be prevented, as some lifestyle behaviors contribute to developing the condition. 

Related: Can Eating Too Much Sugar Cause Diabetes? Here’s What Experts Say

For example, studies have shown that diet plays a role in diabetes prevention and that diets high in added sugar, saturated fats, ultra-processed foods, sodium and excessive calories are associated with an increased risk of diabetes.

Many studies and guidelines on diabetes and diet focus primarily on macronutrients—carbs, fats and protein. But researchers in India wanted to know if there was a link between micronutrients—vitamins and minerals—and diabetes. Here’s what they found in their systematic review and analysis from January 2025, published in BMJ Nutrition, Prevention & Health.

How Was This Study Conducted?

After searching for previously published studies on diabetes and micronutrients and weeding out the ones that didn’t meet their criteria, researchers ended up with 132 studies with a total of 52,501 participants for this review and meta-analysis. Participants were men and women of multiple ethnicities at least 18 years old with type 2 diabetes, with or without complications.

The studies included information on participants’ micronutrient status—including if they were deficient in specific vitamins and minerals based on their bloodwork. All the studies were published between 1998 and 2023 and were from many different countries, giving these researchers a global perspective.

What Did This Study Find?

There were several findings from this review and meta-analysis:

• Over 45% of the type 2 diabetes population had multiple micronutrient deficiencies

• 40% of the participants with diabetic complications had micronutrient deficiencies

• Women were more likely to be affected by micronutrient deficiencies than men

• Vitamin D deficiency was the most common deficiency with a prevalence of over 60% among people with type 2 diabetes

• Magnesium ranked second as the most common deficiency with about 42% of people with type 2 diabetes deficient in magnesium

• In a subgroup of people with diabetes taking metformin, a common diabetes medication, vitamin B12 deficiency was present in almost 29% of participants

Here’s where the chicken-and-egg scenario comes in. Researchers can’t say whether the micronutrients may have played a role in these people developing diabetes, or if diabetes might have caused the micronutrient deficiencies. They can only conclude that there is some sort of correlation between type 2 diabetes and micronutrient deficiencies, including vitamins D and B12 and magnesium.

How Does This Apply to Real Life?

You don’t have to have diabetes to be deficient in any of these nutrients. All three—vitamin D, vitamin B12 and magnesium—are commonly deficient in the general population as well. There are estimates that about 25% of Americans are vitamin D deficient with an additional 40% having below-optimal blood levels of the sunshine vitamin. Between 40% and 80% of people in developed countries are deficient in vitamin B12. Plus, about half of us aren’t getting enough magnesium.

Because these deficiencies are common in both the general population and those with type 2 diabetes, one might hypothesize that the deficiency may have come first. Regardless, it’s important to eat a balanced variety of foods to cover your nutrient needs, whether you have diabetes or not.

Vitamin B12 is found in animal products, like meat, fish and dairy. Fortified cereals, plant-based milks and nutritional yeast are plant-based sources of vitamin B12.

Our bodies manufacture vitamin D from sunlight exposure, but many things can influence this process. For example, you need to expose enough of your body—head, arms and legs—which is difficult to do in colder months. A few foods do contain vitamin D. Egg yolks, mushrooms, cod liver oil, beef liver and fatty fish, like salmon, tuna and swordfish, all naturally contain vitamin D. You’ll also find some foods fortified with it, including cow’s milk, cheese, yogurt, soy milk, orange juice and cereal.

Magnesium, too, is in a wide variety of foods. Regularly eating nuts, seeds, nut and seed butter, soy, legumes, fruits and veggies can help ensure you’re getting enough magnesium.

Even dark chocolate provides magnesium. We recently reported that researchers connected regularly eating a small amount of dark chocolate—but not milk or white chocolate—to a lower risk of type 2 diabetes. For that study, they hypothesized that dark chocolate’s antioxidants may have offered protection. Magnesium may have played a role, too. Add nuts to your dark chocolate for another magnesium boost.

If your diet is more centered on ultra-processed and high-added-sugar foods and beverages, there’s a good chance you’re not getting a sufficient amount of some of the micronutrients. But for many, completely overhauling your diet all at once is too overwhelming.

Instead, pick one or two items you eat every day or almost every day and swap it with a whole food or something with less sugar, sodium or saturated fat. For example, if you drink soda every day, swap one of your daily sodas with water. If you need bubbles, sparkling water will work, too. Add fruit slices or a splash of 100% fruit juice to your glass if you need more flavor. Once you’ve made that one swap a habit, do more—swap another soda—and continue doing this until you’ve said adios to your sugary drink habit.

Or if you eat fast food several times a week, choose one of those meals to swap with a meal you’ve prepared at home. If you’re in the habit of reaching for something with a lot of added sugar or caffeine for your afternoon pick-me-up, try having something nourishing instead, like a handful of nuts and a piece of dark chocolate or a string cheese and a piece of fruit. And, perhaps most importantly, make sure you’re hydrating.

The Bottom Line

This study found that a high percentage of people with type 2 diabetes tend to be deficient in three micronutrients: vitamins D and B12 and magnesium. These are also commonly deficient nutrients in the general population. You are more likely to get the recommended daily intake of these micronutrients by eating a variety of foods.

If you worry that you may be low in these nutrients, a registered dietitian and your healthcare practitioner can help you with bloodwork to test your nutrient levels and develop individualized strategies for incorporating foods that are friendlier to your body and brain. And remember—small steps now will lead to big changes in the long run.

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