Magnesium is a mineral that has been shown to improve insulin sensitivity, thereby helping blood sugar control and lowering insulin levels. Lowering insulin levels is key for improving polycystic ovarian syndrome (PCOS) because excess insulin stimulates ovaries to make male-type hormones (androgens, like testosterone) that cause symptoms of PCOS. Thus, magnesium supplementation has the potential to help PCOS sufferers.

This study followed 102 subjects for 3 months - half taking 2.5g per day of magnesium chloride (about 300mg of elemental magnesium) and half taking placebo. The subjects were non-diabetic, not pregnant and did not have high blood pressure but they did have very low levels of serum magnesium, suggesting they could benefit from magnesium supplementation. Compared to the placebo group, the magnesium group had:

  • a significant improvement in fasting insulin levels

  • significantly lower fasting blood sugar

  • lower blood pressure

  • a significant improvement in blood magnesium levels

This suggests that magnsesium-deficient people are likely to experience improved blood sugar regulation after 3 months on magnesium supplementation. 

How do I know if I have magnesium deficiency?

It is important to note that serum magnesium may only be reflective of recent dietary intake and you may still have low tissue levels of magnesium even if your blood test comes back ok. Here are some key risk factors for magnesium deficiency:

  • high stress levels

  • high alcohol intake

  • high caffeine intake

  • low intake of magnesium in your diet - magnesium is in dark green leafy veggies, nuts, needs, grains, legumes, fish, figs, avocadoes, bananas and dairy products. You need to be eating a abundance of these foods to get enough because magnesium can be poorly absorbed from some sources (although moderate dairy intake as too much can mess with insulin too).

If you still aren't sure if you need magnesium there is no harm in giving it a try and you really could benefit from it if your insulin levels are high or you get sugar cravings. Magnesium is a very safe mineral to take because there is no toxicity with having too much (you may get nausea or loose stools with too much though). While you're at it, have your insulin levels checked before and after the 3 months and see the difference for yourself.


Guerrero-Romero F, Rodríguez-Morán M. Magnesium improves the beta-cell function to compensate variation of insulin sensitivity: Double-blind, randomized clinical trial. Eur J Clin Invest. 2011;41(4):405-410. doi:10.1111/j.1365-2362.2010.02422.x.