The health benefits of Mg intake for people with diabetes is extensively documented, however the proportion of people meeting the recommended daily allowance (RDA) for Mg remains low and supplementation in high-risk populations (such as diabetes sufferers, older people, and pregnant women) is often necessary. Supplementation not only assuages the symptoms associated with metabolic diseases but also gastrointestinal and infectious diseases.
The current (updated) review and meta-analysis of 25 random, double-blind controlled trials (RCTs), which investigated the health benefits of Mg in relation to diabetes, underpins earlier findings about the positive association between Mg supplementation and people with or at a high risk of diabetes. In addition, the review asserts that Mg performance improves when insulin is present, and suggests intake is well-tolerated among study subjects, with no significant adverse effects.
Primary analysis compared the parameters of glucose metabolism and insulin sensitivity between subjects treated with oral Mg supplementation and compared to the placebo. The difference between mean Mg and placebo groups was calculated using follow-up data with 95% confidence intervals (CIs), applying a random-effect model.
The main outcome was a decline in insulin resistance with Mg intake, especially in subjects with heightened risk of diabetes, which suggests insulin enhances Mg functionality.
The review states: “Mg may have an action in improving insulin secretion from pancreatic beta-cells…. whilst the main action of Mg seems to be attributable to a decrease in insulin resistance, particularly in those at high risk of diabetes, indicating that it is likely that Mg acts better when a deposit of insulin is present.”
Other notable observations on the effect of Mg on glucose and insulin-sensitivity include a significant reduction in fasting plasma glucose (FPG) in 325 participants with diabetes and in 482 subjects at high risk of diabetes in 11 studies. Considerable improvements in oral glucose tolerance (OGTT) two hours after supplementation were also identified in three studies involving 210 subjects.
To qualify for the review studies had to involve RCT protocol, follow a double-blind design, include participants with diabetes or subjects at high-risk of developing diabetes, use oral magnesium supplementation, include an assessment of glucose metabolism or insulin sensitivity parameters, and adhere with sufficient quality standards.
Several conditions were considered as placing people at high risk of diabetes, including obesity/overweight, metabolic syndrome, renal failure, family history of diabetes, and prediabetes.
The vast majority of studies under review (11) focused on subjects with type 2 diabetes, one targeted pregnant women, and another subjects with type 1 diabetes. Ten RCTs had a parallel design, while three used a crossover design.
Mg intake of 361 diabetic participants was monitored over an average 12-week period and compared with 359 participants in the placebo. Participants treated with Mg had an average age of 50.6 (49.9 in placebo) years, a mean BMI (suggestive of overweight status) and were predominantly women.
A further twelve RCTs investigated the effect of Mg on subjects considered to be at high risk of developing diabetes, such as those with weight issues (overweight or metabolically obese), presenting prediabetes symptoms or polycystic metabolic syndrome. In these studies, 477 subjects were treated with Mg (480 in the placebo) for an average 14 weeks (between 4-24). Participants treated with Mg had a mean age of 42.5 years, a mean BMI of 28.8 kg/m2 and were predominantly males; the participants treated with placebo had a mean age of 45.6 years and mean BMI of 28.9 kg/m2.
The review was carried out by two independent investigators who identified relevant literature using several databases and extracted key data for analysis, and a third investigator checked the data. Jadad’s quality scoring system was used to assess the quality of RCT material, based on description and appropriateness of randomization, blinding (placebo) procedures, and description of subject withdrawals.
In the event of disagreement between the two reviewers, a senior reviewer with experience in diabetes and metabolic disease (LD) was called upon to mediate a consensus among the three reviewers.
Veronese. N., Dominguez. L.J., Pizzol. D., Demurtas. J., Smith. L., Barbagallo. M.,
“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”