# Magnesium for blood sugar and type 2 diabetes: the evidence Source: https://magnesiumguide.uk/benefits/blood-sugar-and-diabetes/ Author: Nell Hartley · Updated 2026-11-05 **Short answer:** A little, mainly in people who are short of magnesium. Trials in type 2 diabetes found slightly lower fasting blood sugar, about 0.5 mmol/L on average, but no clear change in HbA1c. In prediabetes, magnesium lowered blood sugar after a glucose drink. It is an add-on to diet, activity and medicines, not a replacement. **Evidence grade:** Moderate evidence. More than one placebo-controlled trial points the same way, but the trials are small, short or mixed in quality. ## Does magnesium lower blood sugar? A little, and mostly in people who are low in magnesium. Placebo-controlled trials in type 2 diabetes found fasting blood sugar fell slightly with magnesium, while HbA1c, the measure of your average blood sugar over two to three months, did not change clearly. We grade the evidence **moderate**, using [our four evidence grades](/about/evidence-grades/): several double-blind trials and meta-analyses point the same way, but the effects are small and the results vary a lot between studies. Magnesium is needed for insulin to work properly inside cells, so the idea is reasonable. The question is whether taking more makes a difference you would notice, and for most people the honest answer is: not much. ## What did the trials in type 2 diabetes find? Two meta-analyses of double-blind, placebo-controlled trials give the clearest picture: - **Song and colleagues, 2006.** Nine trials with 370 people with type 2 diabetes, a median of 360 mg of magnesium a day for 4 to 16 weeks. Fasting blood sugar ended about 0.56 mmol/L lower than with placebo. HbA1c was 0.31 percentage points lower, but that difference could have been chance. Blood pressure did not change, and HDL ("good") cholesterol rose slightly. - **Veronese and colleagues, 2016.** Eighteen trials, 12 of them in people with diabetes. Magnesium lowered fasting blood sugar in people with diabetes compared with placebo, but the result only just reached significance and the trials disagreed with each other a great deal. An updated analysis in 2026 pooled 15 trials with 1,085 people and looked at insulin resistance. It found no significant improvement in insulin levels or HOMA-IR, a common measure of insulin resistance, in people with diabetes or prediabetes. People who started with higher insulin resistance seemed to respond more. ## Who gains most from magnesium? People whose blood magnesium is already low. The most striking results come from a group in Mexico that only recruited people with low magnesium: - In 63 people with type 2 diabetes and low blood magnesium, a daily magnesium chloride solution for 16 weeks led to lower fasting blood sugar, lower HbA1c and better insulin sensitivity than placebo (Rodríguez-Morán and Guerrero-Romero, 2003). - In 116 adults with newly found prediabetes and low magnesium, 382 mg of magnesium a day as magnesium chloride for four months lowered fasting and after-meal blood sugar. About half of the magnesium group improved their blood sugar category, compared with 7% on placebo (Guerrero-Romero and colleagues, 2015). These are encouraging, but they are single trials from one research group, in people chosen because they were deficient. They don't tell us what happens if your magnesium is normal. See [signs of low magnesium](/basics/deficiency-symptoms/) and [the magnesium blood test](/basics/magnesium-blood-test/) for how a shortfall is found. ## What about prediabetes? The evidence is thinner. A 2026 meta-analysis of five trials with 384 adults with prediabetes found magnesium did not significantly lower fasting blood sugar. It did lower blood sugar two hours after a glucose drink, by about 1 mmol/L, and improved insulin resistance scores and some blood fats. The 2016 Veronese analysis also found better two-hour results in people at high risk of diabetes. Five small trials are not enough to call this proven. ## Why do people with diabetes often have low magnesium? Partly, it seems, because of the diabetes itself: high blood sugar is thought to make the kidneys lose more magnesium in urine. Some medicines that people with diabetes often take, such as long-term acid-reducing tablets and some diuretics, can lower magnesium too (see [medicines and magnesium](/safety/drug-interactions/)). Observational studies show the link clearly. A 2026 review of 24 studies found people with the highest blood magnesium were about a third less likely to have type 2 diabetes than those with the lowest. A 2011 analysis of 13 studies following more than half a million people found that each extra 100 mg of magnesium a day in the diet was linked to a 14% lower risk of developing type 2 diabetes. But a link is not proof. Magnesium-rich foods such as wholegrains, beans, nuts and seeds also bring fibre, and people who eat them tend to have healthier diets overall. Low magnesium may be partly a result of diabetes rather than a cause. ## How would you take magnesium for blood sugar? If you have type 2 diabetes or prediabetes and want to try it: - **Talk to your GP or diabetes nurse first.** Magnesium is not part of NHS diabetes treatment, and it should sit alongside the things that work best: diet, weight loss if needed, activity and prescribed medicines. - **Ask about a blood test.** The best results were in people with low magnesium, so it is worth knowing where you stand. - **Food first.** [Foods high in magnesium](/basics/food-sources/) such as pumpkin seeds, almonds, spinach and beans fit well with a diabetes-friendly diet. - **Keep supplements to 400 mg a day or less.** The NHS says this amount from supplements is unlikely to cause harm. The trials in type 2 diabetes used a median of 360 mg a day. See [dosage and timing](/how-to-take/dosage-and-timing/). - **Pick a form you tolerate.** No form has been shown to be better for blood sugar. Glycinate and citrate are common choices; see [forms of magnesium compared](/forms/). ## Is magnesium safe if you have diabetes? For most people with diabetes, normal doses are safe. The main exception is kidney disease, which is more common in people who have had diabetes for a long time. Damaged kidneys can't clear extra magnesium, so it can build up to harmful levels. Don't take magnesium supplements if you have kidney disease unless your doctor advises it. Higher doses often cause loose stools or diarrhoea, which can upset blood sugar control if you can't eat normally. If that happens, lower the dose or switch form. See [side effects](/safety/side-effects/). ## What doesn't the evidence show? That magnesium can replace diabetes medicine, that it prevents diabetes, or that it reduces complications such as heart disease, eye or nerve damage. The trials measured blood sugar and insulin for a few months, not long-term health. A modest fall in fasting blood sugar is welcome, but it is much smaller than the effect of standard diabetes treatment. ## Frequently asked questions ### Does magnesium lower blood sugar? Slightly, in some people. Pooled trials in type 2 diabetes found fasting blood sugar was about 0.5 mmol/L lower after around three months, but HbA1c, the longer-term measure, did not change clearly. The biggest effects came from trials in people whose blood magnesium was low to begin with. ### Is low magnesium common in type 2 diabetes? It is more common than in people without diabetes. Observational studies consistently link lower blood magnesium to higher blood sugar and more type 2 diabetes. High blood sugar is thought to increase magnesium loss through the kidneys, so low levels may be partly a result of diabetes as well as a possible contributor. ### Can magnesium prevent type 2 diabetes? Nobody knows yet. People who eat more magnesium are less likely to develop type 2 diabetes, but that could be because magnesium-rich foods such as wholegrains, beans and nuts come with fibre and other benefits. No trial has followed people long enough to see whether supplements prevent diabetes. ### Can I take magnesium with metformin or other diabetes medicines? Ask your GP or pharmacist before you start. Magnesium can affect how some medicines are absorbed, so timing may matter, and diabetes can affect the kidneys, which clear excess magnesium. Keep taking your diabetes medicines as prescribed: magnesium is not a substitute for them. ### Which magnesium is best for blood sugar? No form has been shown to work better. The trials with the clearest results used magnesium chloride solution, and others used magnesium oxide and other forms. A form you can take every day without stomach upset is the sensible choice. ## References 1. [Song Y et al. Effects of oral magnesium supplementation on glycaemic control in Type 2 diabetes: a meta-analysis of randomized double-blind controlled trials. Diabetic Medicine, 2006.](https://pubmed.ncbi.nlm.nih.gov/16978367/) 2. [Veronese N et al. 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, 2016.](https://pubmed.ncbi.nlm.nih.gov/27530471/) 3. [Amiri A et al. Oral magnesium supplements and insulin resistance in individuals with diabetes and pre-diabetes: an updated systematic review and meta-analysis of randomized controlled trials. BMC Nutrition, 2026.](https://pubmed.ncbi.nlm.nih.gov/42426860/) 4. [Basit A et al. Impact of oral magnesium supplementation on glycemic and cardiometabolic outcomes in prediabetic adults: a systematic review and meta-analysis. Journal of Diabetes and Metabolic Disorders, 2026.](https://pubmed.ncbi.nlm.nih.gov/41641401/) 5. [Rodríguez-Morán M, Guerrero-Romero F. Oral magnesium supplementation improves insulin sensitivity and metabolic control in type 2 diabetic subjects: a randomized double-blind controlled trial. Diabetes Care, 2003.](https://pubmed.ncbi.nlm.nih.gov/12663588/) 6. [Guerrero-Romero F et al. Oral magnesium supplementation improves glycaemic status in subjects with prediabetes and hypomagnesaemia: a double-blind placebo-controlled randomized trial. Diabetes and Metabolism, 2015.](https://pubmed.ncbi.nlm.nih.gov/25937055/) 7. [Dong JY et al. Magnesium intake and risk of type 2 diabetes: meta-analysis of prospective cohort studies. Diabetes Care, 2011.](https://pubmed.ncbi.nlm.nih.gov/21868780/) 8. [Rashki A et al. Serum magnesium and risk of hyperglycemia, type 2 diabetes, and prediabetes: a systematic review and dose-response meta-analysis of observational studies. Journal of Health, Population and Nutrition, 2026.](https://pubmed.ncbi.nlm.nih.gov/42907896/) 9. [NHS. Type 2 diabetes: treatment.](https://www.nhs.uk/conditions/type-2-diabetes/treatment/) 10. [NHS. Vitamins and minerals: others (magnesium).](https://www.nhs.uk/conditions/vitamins-and-minerals/others/)