Vitamin D, Magnesium and B12 Deficiencies Common in Type 2 Diabetes
A global review finds nearly half of type 2 diabetes patients suffer from micronutrient deficiencies.

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A new systematic review conducted by researchers in India, found that nearly half of individuals with type 2 diabetes (T2D) suffer from micronutrient deficiencies – with vitamin D, magnesium and vitamin B12 among the most affected.
The study was published in BMJ Nutrition, Prevention & Health.
The hidden hunger crisis in type 2 diabetes
Micronutrient deficiency, often referred to as "hidden hunger," occurs when individuals consume sufficient calories but lack essential vitamins and minerals necessary for optimal health. Unlike acute malnutrition, which presents visible symptoms, hidden hunger can silently contribute to chronic diseases by impairing key physiological functions, including metabolism, immune response and insulin regulation.
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Subscribe for FREEOne micronutrient of particular concern is vitamin D, which is a steroid hormone that plays an important role in glucose metabolism and insulin function. Research has shown that vitamin D is involved in pancreatic beta-cell function, insulin secretion and insulin sensitivity – all of which are critical factors in preventing and managing T2D. Previous research have suggested that low vitamin D levels are linked to an increased risk of developing insulin resistance, a hallmark of T2D.
Beyond vitamin D, deficiencies in magnesium, iron and vitamin B12 have also been linked to metabolic disturbances in T2D. Magnesium is essential for insulin action and deficiency has been associated with poor glycemic control and increased risk of complications in diabetes patients. Iron deficiency can contribute to anemia, which worsens fatigue and exacerbates the systemic effects of diabetes. Vitamin B12 deficiency is also an issue, particularly among those taking metformin, a first-line medication for diabetes that has been shown to interfere with B12 absorption.
Despite growing evidence of the role these micronutrients play in diabetes, there has been limited large-scale research examining their prevalence in T2D patients. Existing literature has focused on individual nutrients rather than taking a comprehensive look at the broader issue of hidden hunger.
A high pervasiveness of deficiencies in T2D patients
A recent systematic review and meta-analysis aimed to assess the global prevalence of micronutrient deficiencies among individuals with T2D. Researchers conducted a literature search across multiple databases, covering studies published between 1998 and 2023. The search utilized keywords such as "micronutrient deficiency," "multiple vitamin deficiencies," "type 2 diabetes mellitus" and "T2D." From this search, 132 studies encompassing 52,501 participants were selected for analysis.
They observed that ~45.3% of T2D patients worldwide experience micronutrient deficiencies. Vitamin D deficiency was the most prevalent, affecting 60.5% of individuals with T2D, while magnesium deficiency was identified in 42% of patients and 29% were deficient in vitamin B12. Medication also had an impact on their results, finding vitamin B12 deficiency was more common in individuals using metformin.
The study also highlighted disparities in micronutrient deficiencies across different demographics. Women with T2D exhibited a higher prevalence of deficiencies (48.62%) compared to men (42.53%). Geographically, the highest prevalence was observed in the United States, with a rate of 54.04%.
Addressing micronutrient deficiencies
“The treatment of type 2 diabetes often tends to focus on energy metabolism and macronutrients, but the identification of a higher prevalence of specific micronutrient deficiencies in those affected is a reminder that optimising overall nutrition should always be a priority,” said Shane McAuliffe, a visiting senior academic associate at the NNEdPro Global Institute for Food, Nutrition and Health, which co-owns the journal.
One of the biggest challenges in understanding the relationship between micronutrient deficiency and T2D is determining whether these deficiencies contribute to the onset of the disease or are a consequence of it. While research suggests that deficiencies in vitamin D, magnesium and vitamin B12 can negatively impact glucose metabolism and insulin function, it remains unclear whether these deficiencies play a causal role in diabetes development, or if they arise as a result of the disease and its treatments.
“This systematic review exemplifies the double burden of malnutrition in action, whereby nutritional deficiencies and diet-related non-communicable diseases, such as type 2 diabetes, co-exist,” said McAuliffe.
“The findings should help to focus research and policy initiatives aimed at furthering our understanding of the causes and effects of these deficiencies and the potential for targeted and tailored interventions,” he added.
Reference: Mangal DK, Shaikh N, Tolani H, et al. Burden of micronutrient deficiency among patients with type 2 diabetes: systematic review and meta-analysis. BMJNPH. 2025:e000950. doi: 10.1136/bmjnph-2024-000950
This article is a rework of a press release issued by BMJ Group. Material has been edited for length and content.