Researchers in India pooled data from 132 studies published between 1998 and 2023 that involved more than 50,000 participants with type 2 diabetes.
Key findings included:
- Vitamin D deficiency affected 60 percent of people in the studies.
- Magnesium deficiency affected 42 percent.
- Iron deficiency affected 28 percent.
- Vitamin B12 deficiency affected 22 percent overall, and 29 percent of people taking metformin.
- Women were more likely to experience micronutrient deficiency (49 percent) compared with men (43 percent).
Interestingly, the prevalence of micronutrient deficiency among people with type 2 diabetes was 45 percent — but 40 percent in people with diabetes-related complications.
“While this might seem counterintuitive, it could be attributed to increased medical attention and dietary modifications often recommended for individuals with complications, which may lead to better supplementation and correction of deficiencies. However, further research is needed to verify this observation and explore possible explanations,” says lead coauthor Daya Krishan Mangal, MD, professor of medicine at IIHMR University in Jaipur, India.
How Do the Vitamin Deficiencies Found Compare With People Without Diabetes?
Because of a dearth of relevant research, it’s impossible to draw comparisons between people with type 2 diabetes and the general population, according to researchers.
But available data suggests that a higher percentage of people with type 2 diabetes have vitamin and mineral deficiencies compared with healthy individuals without type 2 diabetes, says Dave Bridges, PhD, an associate professor of nutritional sciences and a member of the Diabetes Institute at Michigan Medicine in Ann Arbor, who was not involved in the study.
The nutrient shortfalls found in the study all have different connections with type 2 diabetes, says Dr. Bridges.
Vitamin D
“It’s been known for a long time that low vitamin D is associated with increased risk of diabetes and increased risk of complications to diabetes,” says Bridges.
“So right now, the evidence that vitamin D plays a role in causing type 2 diabetes is pretty weak,” he says.
Magnesium
“Magnesium is actually very important for processing glucose in our tissue and so there’s reason to suspect that it might play a role in glucose control. This is enhanced because having diabetes causes you to excrete more magnesium. Their kidneys don’t maintain magnesium as well,” he says.
This leads to a “vicious cycle,” says Bridges. “Having low magnesium makes you have worsened diabetes, and then having worsened diabetes makes you excrete more magnesium, which then makes you have lower magnesium, which could then further exacerbate your diabetes,” he explains.
B12
“It’s been known for a very long time that metformin impairs vitamin B12 uptake. That’s probably a big part of why this study found so many people to be deficient,” he says.
In a healthy population, only about 3 to 4 percent of people are vitamin B12 deficient, compared with the 29 percent of people with type 2 diabetes taking metformin, says Bridges.
Why Is It Important to Know if Vitamin Deficiencies and Type 2 Diabetes Are Linked?
“This study underscores the potential role of targeted nutritional interventions as complementary to existing diabetes treatments,” says Dr. Mangal. “Addressing these deficiencies could lead to improved glycemic control, a lower risk of complications, and better overall health outcomes.”
The findings also suggest that better monitoring of micronutrients in people at risk for type 2 diabetes, especially for magnesium, may be useful, says Bridges.
“These deficiencies could be improved through supplements, but I always recommend trying to find whole food sources. People could modify their diets to find foods that are higher in these vitamins and minerals to prevent these deficiencies from happening,” he says.