According to research reviewed by Gram, a 2026 cross-sectional study of 91 hospitalized adults found that minerals in blood vary by blood fraction in type 2 diabetes. People with diabetes and reduced kidney filtration had lower plasma magnesium than healthy controls, while whole blood iron was higher in both diabetes groups.
A new study looked at magnesium, calcium, and iron in people with type 2 diabetes, including people whose kidneys filter blood at a reduced rate. According to research reviewed by Gram, the researchers tested blood from 91 hospitalized adults and found that minerals did not look the same across different parts of the blood. Plasma, the liquid part of blood, showed lower magnesium in the group with reduced kidney filtration compared with healthy controls. Whole blood iron was higher in both diabetes groups. However, when iron was measured inside the blood cells and adjusted for how many cells were present, the differences disappeared. The study was small, looked at one moment in time, and cannot prove that these mineral changes cause kidney or diabetes problems. It does suggest that where minerals are measured in the blood may matter for understanding diabetes, and larger studies are needed before doctors use these tests for diagnosis.
Key Statistics
A 2026 cross-sectional study of 91 hospitalized adults found that people with type 2 diabetes and reduced kidney filtration had lower plasma magnesium than people without diabetes.
A 2026 cross-sectional study of 91 hospitalized adults found that whole blood iron was elevated in both type 2 diabetes groups, but hematocrit-adjusted iron inside blood cells did not differ significantly between groups.
The 2026 study grouped 32 people without diabetes, 29 people with type 2 diabetes and normal kidney filtration, and 30 people with type 2 diabetes and reduced kidney filtration.
The Quick Take
- What they studied: Researchers wanted to know whether magnesium, calcium, and iron levels differ in various parts of the blood in people with type 2 diabetes, and whether those levels change depending on how well the kidneys filter blood.
- Who participated: 91 adults staying in a hospital were split into three groups: 32 people without diabetes, 29 people with type 2 diabetes and normal kidney filtration, and 30 people with type 2 diabetes and reduced kidney filtration. Researchers also recorded what the patients ate during a three-day hospital stay.
- Key finding: Plasma magnesium was lower in people with diabetes and reduced kidney filtration than in healthy controls. Whole blood iron was higher in both diabetes groups. When iron was measured inside the blood cells and adjusted for cell count, no clear differences appeared between the groups.
- What it means for you: These results do not give you a reason to change your diet or test your minerals on your own. They do suggest that doctors may eventually learn more about diabetes by looking at minerals in different parts of the blood. If you have diabetes, talk with your care team about your kidney and mineral levels.
The Research Details
This was a cross-sectional study, which means researchers took a snapshot of each person at one point in time rather than following them over months or years. The study took place at one medical center and included adults who were already in the hospital. Participants were placed into three groups: healthy people without diabetes, people with type 2 diabetes whose kidneys filtered blood at a normal rate, and people with type 2 diabetes whose kidneys filtered blood at a reduced rate.
Kidney filtration was estimated with a standard formula called the MDRD equation, which uses blood creatinine, age, sex, and other factors. The researchers were careful to note that this grouping was not a diagnosis of chronic kidney disease. Magnesium, calcium, and iron were measured in plasma and whole blood using a laboratory method called atomic absorption spectrometry. Calcium in plasma was adjusted for albumin, a common blood protein. Iron and magnesium inside blood cells were estimated using each person’s hematocrit, which is the share of blood made up of cells. Calcium inside blood cells could not be measured.
To look at diet, the team used three-day food diaries kept during the hospital stay. This shows what patients were served and ate in a controlled setting, not their usual eating habits at home.
A cross-sectional design is useful for spotting patterns and generating ideas for future research. Because the study compared minerals across several blood compartments at once, it can show whether a mineral looks different in plasma than in whole blood or blood cells. That detail matters because a single blood test can give a misleading picture. The design cannot prove that low magnesium causes kidney changes or that iron builds up inside cells, so the results point toward questions rather than answers.
The study used standard laboratory methods and statistical tests designed to compare several groups fairly. The researchers also corrected for multiple comparisons, which reduces the chance of false positive results when many tests are run. The sample of 91 adults is modest, and all participants came from one hospital, so results may not apply to the wider population. Because participants were hospitalized, they may be sicker or eating differently than people living at home. The researchers openly stated that the study did not adjust for several clinical factors, which means other health conditions or medications could have influenced the results.
What the Results Show
The main finding was that minerals did not behave the same way in every part of the blood. Plasma magnesium was lower in people with type 2 diabetes and reduced kidney filtration compared with people without diabetes. This suggests that magnesium may be affected when both diabetes and kidney filtration are involved.
Calcium in plasma, after adjustment for albumin, was also lower in the reduced kidney filtration group than in the diabetes group with normal filtration. This pattern hints that kidney function may play a role in how calcium is handled in the body, although the study cannot confirm the cause.
Whole blood iron was elevated in both diabetes groups compared with controls. Whole blood includes the cells as well as the liquid part, so this result shows more iron in total blood without showing where that iron sits. When researchers adjusted iron inside the blood cells for hematocrit, the differences between groups were no longer significant. This suggests the extra iron seen in whole blood may not be packed inside the cells.
The researchers were clear that these findings do not show iron piling up inside cells or a specific iron-blocking process called hepcidin-mediated sequestration. Those ideas need direct testing in future studies.
The study also looked at links between blood cell iron and standard blood counts, using a statistical method that checks whether two measures move together. These links help explain how iron measurements relate to other blood markers. Still, the results were not strong enough to show that iron levels inside cells are a reliable marker of diabetes or kidney health. The study also recorded hospital diets, which allowed researchers to consider food as one possible influence on mineral levels, though the diet data were short and collected in a hospital setting.
Earlier research has linked type 2 diabetes with disturbances in minerals such as magnesium and iron, and magnesium loss in urine is often discussed in people with diabetes and kidney strain. This study adds information by measuring minerals in several parts of the blood at once, instead of only in plasma. That approach may explain why some past results looked inconsistent: a mineral can look normal in one blood fraction and different in another. The findings fit with the idea that mineral status in diabetes is complex, but this single study does not settle the debate.
The study was small and came from one hospital, so the results may not apply to other groups of people. Because it was cross-sectional, it cannot show cause and effect. A low mineral level might be a result of diabetes or kidney changes, or both might be driven by something else entirely. The study did not fully adjust for other conditions, medicines, or lifestyle factors that can affect minerals. Kidney filtration was estimated with a formula rather than a direct measurement, and the groups were not formal diagnoses of kidney disease. Calcium inside blood cells could not be measured at all. The three-day hospital diet records may not reflect what people eat at home. Finally, some statistical details in the published abstract were unclear, so readers should review the full paper before drawing firm conclusions.
The Bottom Line
Based on this single cross-sectional study, the strongest takeaway is that minerals should be interpreted carefully and by looking at more than one blood measure. Confidence that the findings apply broadly is low right now because the study was small and observational. Routine mineral testing for diabetes or kidney health is not recommended based on these results alone. Standard care, including blood sugar control, kidney monitoring, and a balanced diet, remains the evidence-based approach.
People with type 2 diabetes, people with reduced kidney filtration, and clinicians who manage these conditions may find the study interesting. Researchers studying minerals and metabolism will likely find it useful for designing larger studies. People without diabetes or kidney concerns should not change their habits based on this research. Anyone taking supplements of magnesium, calcium, or iron should talk with a doctor before making changes, since needs vary by person.
This study does not offer a timeline for benefits because it did not test any treatment or change in diet. Future research would need to follow people over months or years to see whether mineral patterns predict health outcomes. Any practical use of mineral testing in clinics would likely take several years of additional research and validation.
Frequently Asked Questions
Does type 2 diabetes change magnesium levels in the blood?
A 2026 study of 91 hospitalized adults found that plasma magnesium was lower in people with type 2 diabetes and reduced kidney filtration than in people without diabetes. The study was cross-sectional, so it cannot prove cause and effect.
Is iron higher in people with type 2 diabetes?
Whole blood iron was elevated in both diabetes groups in a 2026 hospital study of 91 adults. When iron inside blood cells was adjusted for hematocrit, the differences were no longer significant, so the extra iron may not be stored inside cells.
Should I get my magnesium or iron tested if I have diabetes?
This single small study does not establish routine mineral testing for diabetes. Standard care includes blood sugar and kidney monitoring. Talk with your doctor before testing or taking supplements, since needs vary by person.
How does kidney function affect blood minerals in diabetes?
In a 2026 study of 91 adults, plasma calcium adjusted for albumin was lower in people with diabetes and reduced kidney filtration than in those with diabetes and normal filtration. Researchers say kidney function may play a role, but more research is needed.
Want to Apply This Research?
- Track your blood test results over time, including kidney function measures such as eGFR and blood sugar levels such as HbA1c, and note any magnesium or iron values your doctor reports. Log the date and the lab name so comparisons stay consistent. Ask your care team which tests are appropriate for you before adding any new measurements.
- Use the app to log daily meals and note foods rich in magnesium, such as leafy greens, nuts, seeds, beans, and whole grains, while staying within any limits your doctor sets for kidney health. Set a reminder to review your meal log weekly with your care team. Avoid starting supplements based on this study alone.
- Create a long-term view by reviewing your kidney function, blood sugar, and any mineral test results every three to six months, or as your doctor recommends. Add notes about medications, hydration, and major health events so trends can be understood in context. Share the summary with your clinician rather than making changes on your own.
This article summarizes a single small cross-sectional study published in the Journal of Clinical Medicine. It shows associations, not cause and effect, and it is not medical advice. Do not start, stop, or change any supplement, medication, or diet based on this research. Talk with your doctor, kidney specialist, or dietitian about your own mineral levels, kidney function, and diabetes care.
This research translation is published by Gram Research, the science division of Gram, an AI-powered nutrition tracking app.