Unfortunately, the prevalence of metabolic syndrome, type 2 diabetes, and the insulin resistance associated with both is increasing rapidly around the world. The main reason for this is our modern lifestyle: apart from our circadian rhythm, the biggest change in recent decades has been in our diet. Not only has our caloric intake increased dramatically with the rise of industrialized foods, but at the same time, we are deprived of many important micronutrients.  One of these is magnesium, which, among other factors, helps to regulate blood sugar levels by contributing to several enzymes that control important steps in carbohydrate metabolism. (1) A deficiency increases blood sugar levels and reduces insulin sensitivity, and also increases anxiety and stress, which then impair sleep - good sleep being one of the most important factors in maintaining healthy blood sugar levels and good insulin sensitivity. Unfortunately, in addition to stress, type 2 diabetes also increases magnesium excretion from the body, exacerbating this vicious cycle, but the good news is that there is a solution. (2,3) 

The link between magnesium deficiency and type 2 diabetes  

Around 10% of people in developed countries have type 2 diabetes, but magnesium deficiency is much more common, affecting up to 75% of overweight people. (4,5) Magnesium in natural foods has also declined significantly in recent decades, so those with a diet high in processed foods are unlikely to get enough magnesium without supplementation. (6) 

Observational studies show that magnesium deficiency significantly increases the risk of diabetes. A 2020 meta-analysis found that higher magnesium intake reduces the risk of type 2 diabetes by 22%. (7) 

In an older meta-analysis, each additional 100 mg of elemental magnesium reduced the risk of diabetes by 15%, while in another, high magnesium intake resulted in a 23% lower risk compared with those who consumed the lowest amounts. (8,9) 

Effects of magnesium on insulin sensitivity in clinical trials 

Could it be that higher dietary magnesium intake proved so protective against type 2 diabetes simply because those who consume more magnesium ate a much healthier diet? Clinical trials clearly show that magnesium supplementation alone significantly improves the parameters that influence blood glucose control the strongest. Of course, the effects of magnesium supplementation often lead to varied results, because in many cases less well-utilized forms are used, or the participants' baseline magnesium levels are not taken into account. In people who had already consumed sufficient magnesium prior to the trial, or in cases where poorly utilizable magnesium oxide was used in the trial, supplementation was less effective than in magnesium-deficient people who received the correct forms at the required dose.    

A 2017 meta-analysis summarized the results of 12 trials that examined the effects of magnesium supplementation on blood glucose levels and insulin resistance. (10) Of the 12 trials, magnesium supplementation significantly reduced fasting blood glucose levels in 8 and insulin levels in 5 trials. In a further 7 trials, it also significantly improved the HOMA-IR value used to quantify insulin resistance. An average of 50 mg of elemental magnesium per day resulted in an improvement of 3-5% in blood glucose levels and insulin sensitivity. Overall, therefore, it was found that magnesium supplementation was effective in improving both blood glucose levels and insulin sensitivity, even in cases where it was supplemented in the poorly utilizable form of magnesium oxide. 

A 2019 randomized trial published after the above meta-analysis found even more encouraging results on magnesium supplementation. (11) Participants were divided into two groups and given the same dietary recommendations, additionally, half of them received 250 mg of elemental magnesium per day in well-utilized forms. Magnesium supplementation in this study also reduced levels of the important biomarker Hba1C, in addition to insulin levels, and resulted in significant improvements in HOMA-IR levels, the above-mentioned measure of insulin resistance. 

Research suggests that magnesium deficiency may be one of the main causes of insulin resistance and poor blood sugar control. Supplementing with the right form of magnesium can effectively eliminate deficiency and improve blood sugar and insulin levels.