Diabetics are often deficient in vitamin D, magnesium, and vitamin B12

Most people with type 2 diabetes have hidden deficiencies in nutrients such as vitamin D, magnesium, and vitamin B12. This is the conclusion of a major meta-analysis published in BMJ Nutrition, Prevention & Health. The researchers also explain how diet, metabolic processes, genetics, and medication can influence the body’s ability to utilize these nutrients. Since type 2 diabetes and its precursor, metabolic syndrome, are spreading like a pandemic, much greater attention should be given to essential nutrients, as deficiencies contribute to the development and worsening of the disease.

The new review article and meta-analysis was led by researchers from India who compiled data from 132 international studies. They documented that over 52,000 patients with type 2 diabetes lacked essential nutrients. More specifically, the study found that:

• 60% were deficient in vitamin D
• 42% were deficient in magnesium
• 29% were deficient in vitamin B12
• Diabetics with more complications generally lacked more nutrients, with this trend most pronounced among American diabetics
• Women were more likely to be deficient in nutrients
• Women were also more genetically predisposed to vitamin D deficiency

It’s worth noting that most diabetics in this study were hospitalized, as the researchers obtained data related to their nutrient levels. This may help explain the severe and widespread deficiencies that contributed to disease progression and other complications.

Why are diabetics deficient in several essential nutrients?

Unbalanced diets and ultra-processed foods lacking the essential nutrients needed for normal blood sugar metabolism and other metabolic processes are a key reason behind the rising prevalence of type 2 diabetes. Another issue is that many people avoid sunlight, which is the primary source of vitamin D. Older individuals and people with darker skin tones also have more difficulty producing the vitamin D precursor in the skin. What’s more, type 2 diabetes is linked to liver and kidney dysfunctions that may hinder the conversion of the precursor into the form measured in the blood, and ultimately into the active steroid form that most cells have receptors for.
Type 2 diabetes is characterized by insulin resistance, where cells are less able to absorb blood sugar. This leads to elevated insulin and blood sugar levels. When blood sugar is high, some of it is excreted in the urine, which in turn flushes out nutrients like magnesium.
Type 2 diabetes is treated with metformin, and long-term use of this drug increases the risk of vitamin B12 deficiency. Since B12 is found only in animal-based foods, a plant-based diet also raises the risk of deficiency.
Chronic comorbidities such as gastrointestinal diseases, cardiovascular disease, neuropathy, and kidney disease can impair the body’s ability to absorb and utilize various nutrients. Poorly managed type 2 diabetes can cause multiple nutrient deficiencies, turning it into a vicious cycle.

What roles do vitamin D, magnesium, and B12 play in blood sugar regulation

Most cells in the body have receptors for vitamin D - including the pancreas’s insulin-producing beta cells. Vitamin D is believed to be important for both insulin production and insulin sensitivity.
Vitamin D also helps regulate chronic inflammation and oxidative stress, both of which are hallmarks of metabolic dysfunction in type 2 diabetes. In addition, vitamin D helps prevent the development of diabetic neuropathy - a serious and disabling complication.
Magnesium is one of the minerals we need in the largest amounts, as it is involved in hundreds of enzyme and metabolic processes. These include energy production, transport of blood sugar across cell membranes, pancreatic function, and interactions with insulin receptors on cells. Magnesium is also important for the enzymes involved in vitamin D activation. Deficiencies in vitamin D and magnesium can disrupt the critical interactions between these nutrients.
Vitamin B12 plays a key role in blood formation and the nervous system. It also supports metabolism by helping to break down food more efficiently. In addition, vitamin B12 - together with vitamin D - helps counteract diabetic neuropathy.

References:

Daya Krishan Manga et al. Burden of micronutrient deficiency among patients with type 2 diabetes: systematic review and meta-analysis. BMJ Nutrition 29 January 2025

Kaitlin Sullivan. New Study Finds Many People with Diabetes Are Lacking Vitamin D and magnesium. Health February 2025

Azadehalsadat et al. The Therapeutic Effects of Magnesium in Insulin Secretion and Insulin resistance. Advanced Biomedical Research 2022