Numerous studies show that diabetes is a major factor in the development of Alzheimer’s disease. In fact, Larry McCleary, M.D., the former chief of Pediatric Neurosurgery at Children’s Hospital in Denver, has devoted years to studying this connection.

According to Dr. McCleary, if you have diabetes, your risk of developing Alzheimer’s is two to three times higher. And as soon as you have insulin resistance — which is the precursor to diabetes — you are at risk.

One explanation for this increased risk is that having diabetes results in damage to the blood vessels of the heart, which causes coronary artery disease and reduction in blood flow. And the brain is a glutton for blood; in fact, it uses 20 percent to 25 percent of the blood the heart pumps. Therefore, any reduction in blood flow damages the brain, and can pave the way for Alzheimer’s disease.

But diabetes on its own may also damage the brain’s functional ability. In order to live, the body must metabolize the glucose in food into energy. This process fuels every cell in the body, including the ones in the brain.

Diabetes interferes with your body’s ability to do this, resulting in a condition Dr. McCleary calls “brain starvation.” The result is that your brain isn’t able to generate all the electrical signals it needs to function properly.

When this occurs in a man-made electrical system, it is called a “brownout.” Dr. McCleary believes the same thing happens in the starved brain, and that these “brownouts,” or interruptions in energy, show up as foggy thinking, difficulty concentrating, and eventually Alzheimer’s disease.

In addition, studies have linked diabetes with “mild cognitive impairment,” which can cause cognitive problems in middle-age people, and sometimes progresses to Alzheimer’s disease. No matter what the link turns out to be, it’s obvious that diabetes negatively affects the brain.