Controlling Blood Sugar Helps Preserve Cognitive Function

Cinnamon Extract and Lipoic Acid May Benefit More than Previously Thought

Controlling Blood Sugar Helps
Preserve Cognitive Function

Avoiding diabetes is not enough—
one must minimize age-related insulin resistance
By Aaron W. Jensen, Ph.D.

This is a lava flow, not a brain. But use your imagination: doesn’t it vaguely resemble the convolutions of a brain? And imagine the “blood” having too much sugar in it, making it biochemically “hot.” Not good for the brain!
ne thing we all want to carry with us into our later years is a sound mind. Yet as we grow older, the risk of mental decline increases dramatically. Loss of cognitive function as we age can be explained by a number of biological and biochemical changes in our body, all of which place the neurons in our brains at higher risk of damage. Our neurons are constantly under assault by a horde of molecular attackers—free radicals, toxic cellular waste products, and, in many cases, excessive levels of normal blood constituents, such as glucose (blood sugar). It’s sort of like being pursued and pecked to death by a flock of relentless seagulls.

As we age, these molecular assaults increase in intensity. As if that weren’t bad enough, the ability of our neurons to resist the onslaught wanes with each passing year. As a result, some neurons die, the functioning of others is compromised, and the complex neural circuitry essential for good memory and sharp cognitive function slowly deteriorates. It’s not a pretty picture.

Poor Health May Cause Cognitive Decline

It should come as no surprise that one of the leading risk factors for almost every disease and medical condition is advancing age. But another factor, one that you can exert tremendous control over, is also very important—and that’s your health. Good health means not just avoiding diseases here and now, but optimizing your long-term wellness so that the chronic diseases associated with aging will find your body an inhospitable place in which to set up shop.

Consider these facts. If you are overweight or obese, you increase your risk of hypertension, heart disease, stroke, cancer, osteoarthritis, diabetes, and almost every other disease known to man. If you have hypertension, you are at increased risk of many diseases, including stroke, heart disease, and diabetes. And if you have diabetes, you increase your risk of heart disease, kidney disease, and glaucoma, to name but a few.

Insulin resistance, which fosters
high blood glucose levels and may
lead to type 2 diabetes, may,
by itself, be sufficient to bring about
a decline in cognitive function.

I’ll bet you know what’s coming next. Right—many different medical conditions signal the potential loss of cognitive function. In a study of over 6000 older adults (aged 70–103), investigators found that patients with diabetes, stroke, or hypertension exhibited poorer performance on a series of cognitive tests than people who did not have these diseases.1

Diabetes Increases the Risk for Dementia

What’s the link between disease and cognitive loss? It turns out that many diseases place chronic stress on our brain neurons, creating a biochemically hostile environment that slowly erodes neural function and impairs neural communication—factors that may ultimately lead to a loss of cognitive abilities.

There is much scientific evidence indicating that people with diabetes are at increased risk for dementia. Although this correlation extends across all age groups, it is much tighter in older diabetic patients. Diabetes causes microvascular changes that impair the local blood circulation to neurons, which can cause central nervous system dysfunction. In addition, metabolic irregularities, such as strong fluctuations in glucose and insulin levels in the blood, place additional stress on neurons.

Insulin Resistance Alone Can Impair Cognitive Function

Unfortunately for us, these factors do not have to be extreme in order to do damage. A mild case of diabetes, e.g., may induce a slow degradation of neurons, and recent research suggests that even people who do not have diabetes but who have poor glucoregulation (regulation of blood glucose levels) may suffer from cognitive impairment.2 Poor glucoregulation stems from insulin resistance, which is a gradual failure of insulin receptors on cell walls to respond to the presence of insulin in the bloodstream; this prevents insulin from facilitating the transport of glucose from the blood into the cells.

In other words, the age-related—but especially obesity-related—condition of insulin resistance, which fosters high blood glucose levels and may lead to type 2 diabetes if not brought under control, may, by itself, be sufficient to bring about a decline in cognitive function. That puts many millions more people at risk than was previously thought.

Healthy Nondiabetics Are Tested

To investigate the role of glucoregulation in cognitive performance, Canadian researchers enrolled 57 healthy nondiabetic men and women aged 55–84.2 All were given a fasting glucose test: after an overnight fast to minimize their blood glucose levels, they consumed a 75-g (300-calorie) glucose drink, and their glucose and insulin levels were measured over the next 2 hours. Those who assimilated this “glucose challenge” efficiently (i.e., those whose blood glucose levels dropped quickly after the initial spike, indicating low insulin resistance) were classified as “good glucoregulators,” and those whose glucose levels remained high for longer periods (indicating high insulin resistance) were classified as “poor glucoregulators.”

Cognitive testing for an astronaut-in-training.
On subsequent visits to the clinic, the patients were tested with a 50-g (200-calorie) glucose challenge, and their cognitive function was determined using a variety of standardized tests that assess the ability to remember and process information. These included tests that assess verbal memory (remembering a string of words after a 2-minute delay); attention and working memory (touching a number of blocks in the same sequence as the test-giver); and executive function (counting backward by 3’s from a randomly picked number).

Poor Glucoregulation = Poor Cognition

The researchers observed two trends. First, the older subjects (over 72) performed less well than the younger ones in the cognitive tests. This is consistent with a mountain of evidence indicating that aging compromises our cognitive abilities. Second, the poor glucoregulators performed less well than the good glucoregulators. That’s interesting, and it should be a wakeup call for those who, regardless of their age, have some degree of insulin resistance.

Not surprisingly, the results showed that the worst performance of all on the tests came from the older subjects who were also poor glucoregulators. Based on their research, the authors concluded, “These results suggest that cognitive functions may be impaired before glucoregulatory impairment reaches levels consistent with a type 2 diabetes diagnosis.” In other words, poor glucoregulation, even in the absence of diabetes and long before old age, can have a significant impact on one’s cognitive abilities.

This study underscores the vital importance not just of avoiding diabetes but also, throughout one’s life, of avoiding insulin resistance, which leads to poor glucoregulation and cognitive impairment. Fortunately, there are several natural options available to help control glucose and insulin levels. A healthy diet helps you limit your caloric intake, and it releases glucose into your bloodstream slowly enough that you can maintain stable blood levels of both glucose and insulin. Regular exercise helps your cells be more receptive to insulin, so less of it is required to maintain healthy blood glucose levels.

MHCP and Lipoic Acid Can Improve Glucoregulation

In addition, some nutritional supplements act as insulin mimetics—compounds that mimic the action of insulin and that may therefore be beneficial in maintaining normal cognitive function. The most potent of these is MHCP (methylhydroxychalcone polymer), a chemical compound found in cinnamon. MHCP has been shown in the laboratory to activate many of the same cellular pathways as insulin. For example, it increases glucose uptake by cells, and it signals muscle and liver cells to convert glucose into glycogen to be stored for later use. A recent clinical trial with type 2 diabetic patients showed that cinnamon powder—containing MHCP, of course—improved glucose levels. (See “Cinnamon Reduces Blood Sugar and Cholesterol Levels” in Life Enhancement, February 2004.)

Centenarians tend to have relatively
low degrees of oxidative stress and
insulin resistance, and good
glucose tolerance. They have
well-preserved insulin sensitivity.

Another agent that mimics the action of insulin, among other beneficial effects, is lipoic acid, which is called “the antioxidant’s antioxidant” for the vital role it plays in maintaining our bodies’ antioxidant defenses. Lipoic acid may also play an important role in removing glucose from the blood. A variety of research indicates that it stimulates the activity of glucose receptors on muscle cells, allowing the cells to absorb more glucose. But that’s not all—lipoic acid is beneficial for neuropathy, a painful complication of diabetes that involves nerve damage. (See “Lipoic Acid Helps Fight Diabetes,” December 2003.)

High Glucose Levels Lead to Oxidative Stress

But why does poor glucoregulation impair cognition? One suggestion put forth is that elevated levels of blood glucose and insulin may provide a pro-oxidant environment. Glucose reacts with oxygen to generate a range of reactive oxygen species (notably superoxides, hydroxyl radicals, and hydrogen peroxide) that can damage the chemical constituents of cells. The higher the glucose levels, the greater the damage. Excessive insulin levels may also accelerate the production of dangerous free radicals.

Thus, people with poor glucoregulation are exposing their systems, including those all-important brain neurons, to potential harm from oxidative stress. And as we age, the harm continues to accumulate unless we actively counteract it.

The Centenarians’ Longevity Secret

In that regard, it is interesting to note that centenarians (people of 100 years or more) tend to have relatively low degrees of oxidative stress and insulin resistance, and good glucose tolerance, according to Italian researchers.3 Blood samples taken from centenarians are lower in oxidized substances than those taken from youngsters aged 80–90 years, suggesting that the centenarians have greater protection from damaging free radicals. It has also been noted that they tend to have higher blood levels of protective antioxidants, such as vitamin E. Coincidence? Not likely.

The researchers suggest that the lack of metabolic derangement observed in centenarians is due to their well-preserved insulin sensitivity (the opposite of insulin resistance). They are saying, in effect, that because centenarians’ blood glucose levels tend to be well regulated, they have been exposed to less oxidative stress over the course of their lives and have accumulated less damage to their tissues. Consequently, they have aged in a much healthier manner, with their mental powers intact.

Do Your Brain a Favor

Do you want to stay mentally fit for the rest of your life? Of course you do! Then make sure that you take good care of your blood sugar, by keeping it in check. We know that obesity increases the risk of hypertension and diabetes, both of which increase the risk of cognitive decline. We now also know, however, that poor glucoregulation, even in the absence of any overt disease (and with or without obesity), can impair our cognitive function.

So eat right, exercise regularly, and do your brain a big favor by taking nutritional supplements, such as MHCP and lipoic acid, that can help your insulin put your glucose where it belongs: inside your cells.


  1. Zelinski EM, Crimmins E, Reynolds S, Seeman T. Do medical conditions affect cognition in older adults. Health Psychol 1998;17(6):504-12.
  2. Messier C, Tsiakas M, Gagnon M, Desrochers A, Awad N. Effect of age and glucoregulation on cognitive performance. Neurobiol Aging 2003;24: 985-1003.
  3. Barbieri M, Rizzo MR, Manzella D, et al. Glucose regulation and oxidative stress in healthy centenarians. Exp Gerontol 2003;38:137-43.

The Mental Rewards of Diet and Exercise

You can exercise control over your blood sugar, and hence your cognitive function, with insulin-mimetic nutritional supplements, such as MHCP and lipoic acid. But you can also “exercise” control over your cognitive function by, well, exercising. Studies indicate that regular exercise in the elderly decreases the risk of cognitive impairment, Alzheimer’s disease, and other types of dementia.1

But you don’t have to wait until late in life to enjoy the mental benefits of physical activity. Research from The Netherlands suggests that men who are most active in their youth retain youthful mental abilities into their old age.2 This has been called the “cognitive reserve” hypothesis, wherein physical activity early in life may delay late-life cognitive deficits. In addition, older people who expend mental energy in solving problems and puzzles consistently perform better on cognitive tests than those who do not.

Aging is associated with a gradual decrease in muscle mass—and as muscle cells disappear, so does some of the body’s capacity for absorbing glucose from the blood. This may cause glucose levels to rise if insulin resistance has set in. Exercise, however, provides a dual counterpunch to this tendency, as it inhibits the loss of muscle mass and makes cells more responsive to insulin.

Dietary changes that tend to occur as we grow older, such as decreased fiber intake and increased carbohydrate intake, also challenge our ability to regulate blood glucose levels properly. This is where insulin-mimetic supplements can be a great help. Finally, obtaining an abundance of dietary antioxidants from fruits and vegetables—and from antioxidant supplements such as lipoic acid—has been linked with improved cognitive function, presumably because they lower oxidative stress in the brain.

  1. Laurin D, Verreault R, Lindsay J, MacPherson K, Rockwood K. Physical activity and risk of cognitive impairment and dementia in elderly persons. Arch Neurol 2001;58(3):498-504.
  2. Dik M, Deeg DJ, Visser M, Jonker C. Early life physical activity and cognition at old age. J Clin Exp Neuropsychol 2003;25(5):643-53.

Caution: If you have diabetes, do not take any supplement that may affect your blood sugar levels without first consulting your physician. Diabetes is a serious disease requiring careful professional management.

Dr. Jensen is a cell biologist who has conducted research in England, Germany, and the United States. He has taught college courses in biology and nutrition and has written extensively on medical and scientific topics.

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