Magnesium is an essential mineral that's slowly disappearing from the modern diet, as industrial agriculture and industrial food processing increasingly dominate our food choices. One of the many things it's necessary for in mammals is proper insulin sensitivity and glucose control. A loss of glucose control due to insulin resistance can eventually lead to diabetes and all its complications.
Magnesium status is associated with insulin sensitivity (2, 3), and a low magnesium intake predicts the development of type II diabetes in most studies (4, 5) but not all (6). Magnesium supplements largely prevent diabetes in a rat model* (7). Interestingly, excess blood glucose and insulin themselves seem to reduce magnesium status, possibly creating a vicious cycle.
Oral Magnesium Supplementation Improves Insulin Sensitivity and Metabolic Control in Type 2 Diabetic Subjects
Most Americans are considered to be deficient in magnesium. This is a mineral and we get it by eating plants or animals that have taken it up. The point Stephan is making is that our industrial system of agriculture isn't replacing essential minerals therefore they are falling as a percent of our diet.
Now if that weren't bad enough, we also have the problem of malabsorption. This means that our bodies are being blocked from taking up these nutrients even when they are present. The chief villain here are grains with the gold star for bad news and all around trouble maker going to wheat. Not only do they drive up blood sugar but they all contain Phytic Acid. This chemical binds to minerals and keeps them from being absorbed into the body. We've been told about the rich nutrients in grains but what we haven't been told is that it hardly makes a difference if the grains block the absorption of these nutrients. This is about magnesium but there are a whole bunch of essential metals that are blocked by this particular chemical. Our buddy, wheat, is particularly good at this. You may as well get this straight, almost every problem I will talk about will implicate wheat as a villain in some way. Wheat and wheat products should be avoided whether you are diabetic or not.
The recommended minimum dosage of magnesium is 350 mg. Here's a list of foods which are magnesium rich. http://www.whfoods.com/genpage.php?tname=nutrient&dbid=75 I would caution you about seeds and beans though. Beans have phytic acid and seeds tend to harbor Omega 6. They won't get you there anyway. Take the supplement on this one. Magnesium Oxide gets absorbed the worst but it's cheap so something is better than nothing.
Caution. Magnesium tends to have a laxative effect so if things start to loosen up, you should go down in dosage until the problem goes away.