When people manage type 2 diabetes, the conversation often circles around carbohydrates, blood sugar, exercise, and medication. A global review points to a quieter issue that can be easy to miss. Many patients may also be running low on vitamins and minerals their bodies need every day.
The pooled analysis found micronutrient deficiency in about 45% of adults with type 2 diabetes. Vitamin D was the most common shortfall at 60.5%, followed by magnesium at 42%, iron at 28%, and vitamin B12 at roughly 29%. The numbers are striking, but they do not prove that taking supplements will improve diabetes control.
What hidden hunger means
Micronutrients are vitamins and minerals needed in small amounts for nerves, muscles, blood cells, bones, and the chemical reactions that turn food into energy. A person can eat enough calories and still lack these nutrients, a problem often called “hidden hunger.”
Why might diabetes and hidden hunger appear together? Diet quality, obesity, kidney function, digestive absorption, and medication use can all shape nutrient levels. Diabetes may also alter how some nutrients are handled, but the direction of cause and effect remains unsettled.
What the researchers found
Daya Krishan Mangal of IIHMR University in Jaipur led the global meta-analysis, which combined 132 studies and 52,501 participants. The papers were published between 1998 and 2023, and nearly all were based in hospitals rather than the wider community. That gives the review breadth, but not a perfect picture of every person living with diabetes.
Deficiencies were more common in women, with a pooled rate just under 49%, and the highest regional estimate appeared in the Americas at 54%. Results varied across countries, likely reflecting differences in food, lifestyle, health care, and the laboratory cutoffs used to define deficiency. In practical terms, one global number cannot predict an individual blood test.
Vitamin D and magnesium lead
Vitamin D helps the body absorb calcium and supports bones, muscles, and other cell functions. NIH vitamin D guidance notes that sunlight, food, and supplements can all contribute, but there is no universal “20 minutes outdoors” rule because season, skin tone, latitude, clothing, and sunscreen change how much the body makes.
Magnesium helps nerves and muscles work and participates in energy production and blood sugar regulation. Good food sources include beans, nuts, seeds, whole grains, and leafy green vegetables, the sort of ingredients that can fit into an ordinary lunch rather than a special “diabetes food.”
Low magnesium can cause fatigue, weakness, or cramps, although mild deficiency may cause no obvious warning.
Metformin and B12
Vitamin B12 helps make red blood cells and keeps the nervous system working. A deficiency can bring fatigue, poor concentration, numbness, or tingling, symptoms that may be mistaken for diabetes-related nerve damage.
Metformin can reduce B12 absorption over time, especially at higher doses or with longer treatment. The American Diabetes Association’s 2026 standards say periodic B12 assessment should be considered for people taking metformin long term. That does not mean stopping the drug, which remains widely used, but discussing symptoms and testing with a clinician.
Salmon, eggs, milk, leafy greens, mushrooms, and other nutrient-rich foods that provide vitamin D and magnesium, two nutrients frequently found to be deficient in people with type 2 diabetes.
Testing beats guessing
Bloodwork can identify vitamin D and B12 problems, but magnesium is trickier because most of the mineral sits inside cells or bone. A normal serum magnesium result may not capture the full picture, so clinicians use symptoms, medical history, diet, kidney function, and medication use alongside laboratory results.
Routine testing of every nutrient in every patient is not yet backed by strong evidence. A more practical approach is targeted testing when there are symptoms, a restrictive diet, long-term metformin use, kidney or digestive disease, anemia, or other clear risk factors. Food remains the starting point for most people.
Supplements need context
A press release from German manufacturer Alexander Pflüger uses the findings to promote its PUR supplement line. But the BMJ review did not test those products, compare supplement brands, or show that vitamin D, magnesium, B12, or K2 pills improve diabetes outcomes. That distinction matters at the pharmacy counter.
Supplements can be useful when a deficiency is confirmed or food intake cannot meet a person’s needs, but more is not automatically better.
High doses can cause side effects, kidney problems, or medication interactions, and magnesium can interfere with some antibiotics. The safest plan is a specific nutrient, a reason for taking it, and a dose chosen with a health professional.
What the evidence cannot prove
Most studies in the review were cross-sectional, meaning they measured diabetes and nutrient status at roughly the same time. They cannot tell whether deficiency came first, resulted from diabetes, or reflected another factor such as diet, income, obesity, or medication. BMJ also lists external funding from Abbott Nutrition Research and Development.
A related Scientific Reports analysis published in December 2025 found only weak links between micronutrient deficiency and blood sugar control.
The authors said the evidence was not strong enough for broad supplementation recommendations. The clearest takeaway is that nutrition deserves a place beside glucose management and confirmed deficiencies deserve targeted care.
The main study was published in BMJ Nutrition, Prevention & Health.
