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The Prediabetes Nutritionist

The Little-Known Benefits of Magnesium in Prediabetes

Magnesium is one of the essential minerals needed for human health, but it is the only one associated with prediabetes thus far. 

There’s plenty of evidence showing that magnesium benefits people with type 2 diabetes, but did you know that it is also beneficial for prediabetes?

In prediabetes, magnesium lowers fasting blood glucose, reduces insulin resistance and inflammation and lowers blood glucose levels after a two-hour oral glucose tolerance test. 

Keep reading to learn more about magnesium, how it impacts prediabetes, how to boost your intake and whether magnesium supplements are necessary for people with prediabetes. 

What is Magnesium, and what does it do?

Magnesium is the fourth most common mineral in the human body after calcium, sodium, and potassium.  The average adult has around 25g of magnesium stored in their body, with approximately 53% in bone tissue, 27% in muscle, 19% in soft tissues and less than 1% in the blood (Schwalfenboerg and Genuis, 2017). 

Since only less than 1% of magnesium is stored in the blood, blood tests measuring serum or plasma levels of magnesium do not reliably indicate magnesium levels in the body (Razzaque, 2018).

Magnesium is vital for human health since over 300 enzymes (proteins) rely on it to carry out different functions, including protein synthesis, energy production, blood pressure regulation, and blood glucose control (Al Alawi, Majoni & Falhammar, 2018). 

Magnesium is also required for bone development, maintaining muscle, heart, and nerve function, and producing genetic material (DNA and RNA) and the antioxidant glutathione (Al Alawi, Majoni & Falhammar, 2018). 

Magnesium is an essential co-helper in the pathways involved in carbohydrate processing.  It makes cells more sensitive to insulin, facilitates insulin secretion from the beta cells in the pancreas and enables insulin to carry out its action – stimulating fat, muscle, and liver cells to absorb excess glucose from the blood.

When magnesium levels are low or deficient, the cells in the body have a reduced capacity to absorb glucose from the bloodstream; the pancreas cannot produce enough insulin, and insulin is less able to do its job.

All these factors lead to insulin resistance.

Notably, magnesium deficiencies also reduce the production of antioxidants (especially glutathione), which further increases inflammation and promotes insulin resistance. 

Prediabetes occurs when blood glucose levels are higher than normal but are not high enough to be classified as type 2 diabetes.  And it tends to arise in people with insulin resistance or those whose pancreas doesn’t produce enough insulin to maintain normal blood glucose levels.  Once cells lose insulin sensitivity, glucose levels in the blood remain elevated, leading to type 2 diabetes over time. 

Past studies show that people with low magnesium levels have a higher risk of prediabetes. 

A Rotterdam study investigated the link between blood magnesium levels and prediabetes risk in 8555 individuals (Kieboom et al., 2017).  The mean age of the participants was 64 years, and 57.8% were women.  Of 7209 participants with normal blood glucose at the start of the study, 1120 developed prediabetes after a median of 5.7 years. 

The researchers found that a 0.1 mmol/l decrease in blood magnesium levels was associated with a 12% increased risk of prediabetes even after accounting for confounding factors.  They also found a significant link between insulin resistance and magnesium levels. 

Notably, insulin resistance accounted for 13% of the effect of low magnesium levels on prediabetes risk. 

In general, low magnesium levels reduce insulin secretion and action, increasing the risk of insulin resistance and prediabetes risk. 

Is magnesium beneficial for prediabetes?

Magnesium deficiency is involved in prediabetes since people with prediabetes appear to have lower blood magnesium levels than healthy controls. 

A recent meta-analysis of ten observational studies involving 2979 people with prediabetes and 10476 healthy controls found that people with prediabetes had significantly lower blood magnesium levels than healthy controls, confirming that magnesium deficiency may play a role in the development of prediabetes (Mousavi et al., 2021). 

Many studies investigating magnesium supplements in diabetes have shown that it improves insulin sensitivity and reduces fasting blood glucose.  While few studies have investigated magnesium’s role in prediabetes, similar findings have been observed. 

A team of scientists in Mexico investigated whether oral magnesium supplements could reduce blood glucose levels in people with prediabetes and low blood magnesium levels (Guerrero-Romero, 2015). 

They included 116 participants aged 30–65 years in the study.

The participants were split into two groups – 59 were given 30ml of magnesium chloride once daily for four months, and the remaining 57 were given 30ml of a placebo for the same duration.  In addition to the supplements or placebo, all participants were advised to eat a healthy diet and exercise three times per week for at least 30 minutes. 

At the start of the study and after four months of treatment, participants’ fasting and two-hour post-meal plasma glucose, serum magnesium levels and insulin resistance were measured. 

Compared to the group taking the placebo, the group taking magnesium supplements had significantly reduced fasting and two-hour post meals glucose levels and insulin resistance.  Serum magnesium levels also significantly increased in the group taking magnesium supplements. 

Notably, a larger percentage of participants taking magnesium supplements had improved prediabetes and lipid profiles than the placebo group. 

“Our results support the hypothesis that oral magnesium supplementation improves the glycaemic status of individuals with prediabetes and hypomagnesaemia [low magnesium levels], a finding that may be of interest in the planning of public-health strategies focused on decreasing diabetes incidence,” the researchers wrote. 

An earlier study by the same research team showed that magnesium supplements reduce c-reactive protein levels, a marker of inflammation (Simental-Mendia, Rodriguez-Moran & Guerrero-Romero, 2014). 

A more recent systematic review and meta-analysis of double-blind, randomized controlled trials assessed the impact of oral magnesium supplements on glucose metabolism in people with or at risk of diabetes (Veronese et al., 2021).  

The researchers found that in people at high risk of diabetes, including those with prediabetes, magnesium supplements significantly improved fasting blood glucose.  Magnesium supplements also significantly reduced insulin resistance and improved the glucose response to the two-hour glucose load tests.  However, magnesium supplementation did not improve glycated haemoglobin (HbA1c) or insulin levels.  

These studies show that magnesium is beneficial for people with prediabetes. 

What are the best sources of magnesium for prediabetes?

Magnesium is abundant in legumes, nuts, seeds, whole grains and green leafy vegetables.  Foods containing fibre typically contain magnesium. 

Some of the best food sources of magnesium for prediabetes include almonds, bananas, black beans, broccoli, brown rice, cashews, flaxseeds, oatmeal, pumpkin seeds, sesame seeds, sunflower seeds, soybeans, sweet corn, tofu, and whole grains. 

What are the symptoms of magnesium deficiency?

Magnesium deficiency occurs with low intakes or increased excretion from the body.  An individual may be deficient in magnesium even if blood tests don’t show it.  However, once blood levels are low, it may indicate a severe deficiency (Barbagallo and Dominguez, 2015). 

Symptoms of magnesium deficiency include:

  • Nausea
  • Poor appetite
  • Vomiting
  • Fatigue
  • Weakness
  • Numbness
  • Tingling
  • Muscle contractions and cramps
  • Seizures
  • Mood disorders
  • Abnormal heart beats

How much magnesium does a person with prediabetes need?

The daily recommended magnesium intake for all adults is 300–400mg daily.  There is currently no specific magnesium recommendation for people with prediabetes. 

Many studies that most people in Europe and North America consume less than the recommended daily allowance of magnesium.  This reduced intake is mainly because most people eat the nutrient-depleted Western diet that often provides only 30-50% of the daily recommended allowance (Piuri et al., 2021). 

Besides this, eating large amounts of processed foods and demineralized water with low intakes of fruits and vegetables grown in magnesium depleted soil contributes to low intakes (Piuri et al., 2021). 

Consequently, health professionals recommend supplements 

The best magnesium supplements for all adults, including those with prediabetes, are magnesium aspartate, magnesium citrate, magnesium lactate and magnesium chloride because the body absorbs them easily. 

So, now you know the benefits of magnesium in prediabetes!

To boost your magnesium levels, I’ll highly recommend eating a healthy diet, including plenty of nuts, seeds, legumes, leafy greens, and whole grains. 

Don’t start taking a magnesium supplement until you get proper advice from your general practitioner, a registered nutritionist, or a dietitian.

A healthy diet with moderate exercise is the best way to increase your magnesium intake, put prediabetes in remission and maintain blood glucose in the normal range.

If you’re not improving your diet yet, what are you waiting on?


  1. Schwalfenberg, G.K., & Genuis, S.J. (2017) The importance of magnesium in clinical healthcare. Scientifica (Cairo); doi: 10.1155/2017/4179326
  2. Al Alawi, A.M., Majoni, S.W., & Falhammar, H. (2018) Magnesium and human health: perspectives and research directions.  International Journal of Endocrinology,
  3. Barbagallo, M and Dominguez, L.J. (2015) Magnesium and diabetes.  World Journal of Diabetes, 6(10), 1152–1157. 
  4. Veronese, N., Watutantrige-Fernando, S., Luchini, C., Solmi, M., Sartore, G., Sergi, G., Manzato, E., Barbagallo, M., Maggi, S., and Stubbs, B. (2016) Effect of magnesium supplementation on glucose metabolism in people with or at risk of diabetes: a systematic review and meta-analysis of double-blind, randomized controlled trials.  European Journal of Clinical Nutrition, 70(12): 1354–1359. 
  5. Veronese, N., Dominguez, L.J., Pizzol, D., Demurtas, J., Smith, L. & Barbagallo, M. (2021) Oral magnesium supplementation for treating glucose metabolism parameters in people with or at risk of diabetes: a systematic review and meta-analysis of double-blind, randomized controlled trials.  Nutrients, 13: 4074
  6. Razzaque, M.S. (2018) Magnesium: are we consuming enough?  Nutrients, 10: 1863
  7. Guerrero-Romero, F., Simental-Mendia, L.E., Hernandez-Ronquillo, & G., Rodriguez-Moran. (2015) Oral magnesium supplementation improves glycaemic status in subjects with prediabetes and hypomagnesaemia: a double-blind placebo-controlled randomized trial.  Diabetes and Metabolism, 41(3): 202–7.
  8. Simental-Mendia, L.E., Rodriguez-Moran, M., & Guerrero-Romero, F. (2014) Oral magnesium supplementation decreases c-reactive protein levels in subjects with prediabetes and hypomagnesaemia: a clinical randomized double-blind placebo-controlled trial.  Archives of Medical Research, 45(4): 325-30.
  9. Mousavi, S.E., Ghoreishy, S.M., Hemmati, A., & Mohammadi, H. (2021) Association between magnesium concentrations and prediabetes: a systematic review and meta-analysis.  Scientific Reports, 11(1): 24388
  10. Kieboom, B.C.T., Ligthart, S., Dehghan, A., Kurstjens, S., de Baaij, J.H.F., Franco, O.H., Hofman, A., Zietse, R., Stricker, B.H., Hoorn, E.J. (2017) Serum magnesium and the risk of prediabetes: a population-based cohort study. Diabetologia, 60(5): 843-853. 
  11. Piuri, G., Zocchi, M., Della Porta, M., Ficara, V., Manoni, M., Zuccotti, G.V., Pinotti, L., Maier, J.A., & Cazzola, R (2021) Magnesium in obesity, metabolic syndrome, and type 2 diabetes. Nutrients, 13(2): 320

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