Magnesium and Blood Sugar Control

What is Magnesium

Magnesium is a mineral that has many responsibilities in the body. Enzymes that perform important roles use magnesium to help carry out biochemical reactions including the production of proteins, muscle and nerve operations, and blood pressure control(1). A growing body of evidence also suggests that magnesium plays a significant role in the regulation of blood sugar and insulin action (1, 2, 4,5)

Most magnesium is located either in cells or bones, making it a difficult mineral to measure in the human body (1). Magnesium levels are tightly regulated by the kidney, which can make an inadequacy even harder to detect if one may be present. Despite magnesium being difficult to measure, there are individuals known to be at a higher risk of having inadequate levels.


Groups at Risk for Magnesium Deficiency

People with diabetes

  • When there is a large amount of glucose in the body, the kidney compensates by getting rid of the glucose through increasing urinary output. Magnesium is also lost through this increased urinary output, following the glucose (1).  It has even been suggested that altered magnesium levels may promote the development of type 2 diabetes (2).

Older adults

  • It has been found that older adults have decreased intakes of magnesium compared to younger adults (1). The amount of magnesium absorbed in the intestine also decreases with age, while the amount excreted by the kidney increases.

People taking certain medications

  • Certain medications including diuretics, antibiotics, and proton pump inhibitors may also have the potential to decrease the amount of magnesium in the body (1)

People with gastrointestinal issues

  • Crohn’s disease, celiac disease, and individuals who have undergone resection or bypass of the small intestine may not be absorbing magnesium sufficiently (1).

Blood Sugar Control and Magnesium

Low magnesium levels are common in individuals with type two diabetes, especially if blood glucose levels are poorly controlled (2). Magnesium is important in controlling the action of insulin and insulin reliant glucose uptake at the cell. Overall, low magnesium levels can impair the action of insulin and increase insulin resistance (2,5)

How Can I Increase Mangensium In My Diet?

The Recommended Dietary Allowance for magnesium is 320 mg for women and 420 mg for men. To reach this daily try aiming to include a few of the magnesium-rich foods listed below.

  • Green leafy vegetables
  • Legumes
  • Nuts and Seeds
  • Whole-Grains
  • Dark Chocolate
  • Avocados

Do I Need A Supplement?

Oral magnesium supplements are available and may be beneficial for those with type 2 diabetes with a magnesium deficiency and to help decrease insulin resistance (2, 4). Consult your doctor before starting magnesium supplementation magnesium as supplement form may interfere with drug absorption, reducing the effect of some medications.

Taking magnesium in supplement form also increases the risk of producing toxicity symptoms like diarrhea, weakness, blurred vision, and cardiac distress (1). The risk of toxicity is not present when obtaining magnesium through food sources because the kidney regulates excessive amounts through excretion in urine (1).  The Institute Of Medicine has set an Upper Limit for adults taking magnesium supplements at 350 mg daily. This does not include intake from food sources (3).

Take-Home Message

If you have diabetes or another condition that increases your risk for magnesium deficiency take a look at your typical diet and aim to consume foods with a good source of magnesium.  If you still think you might be coming up short talk to your doctor and dietitian about starting a supplement.

Vitamin B12 and Metformin

What is Vitamin B12?

Vitamin B12, also known as cobalamin, plays a crucial role in many important functions in the body. It is essential for nervous system fuction, blood cell formation, metabolism of folic acid, and synthesis of DNA (1)In the diet vitamin B12 is typically obtained through consumption of meat or milk.  The best source of vitamin B12 can be found in clams and liver, with a 3 oz portion of clams providing 1400% of the Daily Value!(1,2).

The digestion and absorption of vitamin B12 relies on certain factors to be present in order to be successful. The high acidity of the stomach is an important part of the digestive process because it allows for proteins surrounding vitamin to break free, continuing digestion (2). Different transporters and chaperones are required for absorbtion by the cells. Because there are many steps in the process of digestion and absorption, there are many areas that can go wrong if not all that is required is present.  


Does Taking Metformin Increase Risk of Vitamin B12 Deficiency?

Metformin is the most commonly prescribed drug to individuals with type 2 diabetes and is also used for insulin resistant conditions like polycystic ovarian syndrome (PCOS) (4). Metformin has many benefits for those with insulin resistance, and is prescribed as a first line of treatment. However in a systematic review of multiple research studies, it was concluded that long term use of metformin had a significant impact on a reduction of vitamin B12 concentrations (3).  Studies show the prevelance of vitamin B12 deficiency to be has high as 30% in patients with type 2 diabetes taking metformin (5).


Groups At Risk For Vitamin B12 Deficiency

  • older adults
  • vegetarian or vegan diets
  • use of proton pump ihibitors (PPIs)
  • gastrointesntial disorders (Crohns diease and celiac disease)
  • history of gastrointenstial surgery



What Are The Risks Of Vitamin B12 Deficiency?

People with type 2 diabetes are at an increased risk for cardiovascular complications as well as peripheral neuropathy, and having low vitamin B12 levels increases this risk(2). Elevated cardiovascular disease risk is due to the role vitamin B12 plays in metabolism of an amino acid called homocysteine. Without B12, homocysteine levels stay elevated, which can increase your risk of heart disease (2,3). Peripheral neuropathy is a condition in which multiple symptoms can be present including pain, numbness, tingling in hands or feet, and sensory loss (7). With a vitamin B12 deficiency, damage can occur to myelin sheaths that surround nerves. The myelin sheaths protect nerves and without this protection, neuropathy can develop (7).


Bottom Line

If you are at increased risk for vitamin B12 deficiency you should talk to your doctor or dietitian about a supplement. According to the Institute of Medicine vitamin B12 is not known to cause any adverse side effects at high doses, meaning the risks of supplementing are likely low (6). Studies suggest supplements may be beneficial for certain groups but you will want to make sure you are taking the correct dose and from of the vitamin for the greatest result.  (2,3).