Having a blood sugar level that's even on the "high end" of normal could have damaging effects on the brain, a small new study suggests.

Researchers from the Australian National University found that people whose blood sugar was in the high end of a normal range (but not yet in the range for diabetes or prediabetes) were more likely to experience brain shrinkage in the hippocampus and amygdala -- an effect that normally occurs when a person ages, or experiences dementia.

"These findings suggest that even for people who do not have diabetes, blood sugar levels could have an impact on brain health," study researcher Nicolas Cherbuin, Ph.D., said in a statement.

The new Neurology study included 249 people between ages 60 and 64; all of them had blood sugar levels below 6.1 millimoles per liter (or 110 milligrams per deciliter). For this study, fasting blood sugar levels higher than 6.1 mmol/L were considered prediabetic range, while those higher than 10.0 mmol/L were considered diabetic range. (But according to the Mayo Clinic, for a person who does not have diabetes, a normal fasting blood glucose level is between 3.9 and 5.6 mmol/L, or 70 to 100 milligrams per deciliter.)

The study participants underwent brain scans once at the start of the study, and then once again four years later.

The researchers took into account other possible factors like smoking, drinking alcohol, age and high blood pressure, and found that having a normal-high blood sugar level was responsible for 6 to 10 percent of the loss of brain volume.

"If replicated, this finding may contribute to a reevaluation of the concept of normal blood glucose levels and the definition of diabetes," the researchers wrote in the study.

The study comes on the heels of newly published research in the journal Pediatrics showing a link between metabolic syndrome (which includes insulin resistance seen in prediabetes) and obesity in teens with worsened brain functioning.

That study, conducted by New York University School of Medicine researchers, included 49 teens who had metabolic syndrome, and 62 teens who didn't have metabolic syndrome. They underwent tests to examine their learning and memory abilities. The researchers also found that the teens with metabolic syndrome also had decreased brain volume in the hippocampus.

Having high blood sugar can lead to insulin resistance, which can then lead to diabetes. That's because the body needs to produce insulin to control blood sugar -- but if there is too much sugar in the blood, then the body needs to produce even more insulin to control the sugar, according to the National Institute of Diabetes and Digestive and Kidney Diseases:

Eventually, the pancreas fails to keep up with the body's need for insulin. Excess glucose builds up in the bloodstream, setting the stage for diabetes. Many people with insulin resistance have high levels of both glucose and insulin circulating in their blood at the same time.

When blood sugar gets too high, it can negatively affect blood circulation, the Mayo Clinic explained. When this happens, cholesterol can build up within the blood vessels, leading to health issues like nerve damage, eye and kidney problems, gum disease, heart attack and stroke.

Are your fasting blood sugar levels on the high end? Click through the slideshow for some foods and factors that could help to lower your levels (and of course, check with your doctor about the best options for you):

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  • Dark Chocolate

    A recent study presented at the Experimental Biology 2012 meeting showed that <a href="http://www.huffingtonpost.com/2012/04/30/dark-chocolate-health-cholesterol-blood-sugar_n_1452799.html" target="_hplink">eating dark chocolate</a> could help to lower blood sugar levels <em>and</em> "bad" cholesterol levels, while increased "good" cholesterol levels. The study included 31 people who ate either 50 grams of regular dark chocolate, dark chocolate that had been overheated, or white chocolate, for a 15-day period. However, it's important to note that chocolate is also high in saturated fat and calories, and some may be high in sugar -- so make sure you enjoy in moderation (and get the dark kind!).

  • Get Up And Move Around

    Getting up to <a href="http://www.reuters.com/article/2012/03/07/us-breaks-get-up-move-lower-blood-sugar-idUSTRE8261VM20120307" target="_hplink">move around every 20 minutes</a> could help lower blood sugar levels following a meal, Reuters reported. The finding, published earlier this year in the journal <em>Diabetes Care</em>, showed that getting up and moving after a meal -- which is usually when sugar in the blood increases -- could help to <a href="http://www.reuters.com/article/2012/03/07/us-breaks-get-up-move-lower-blood-sugar-idUSTRE8261VM20120307" target="_hplink">soften the blood sugar spike</a>, compared with just sitting around after eating, according to Reuters.

  • Eat Some Oatmeal

    Oatmeal doesn't <a href="http://diabetes.webmd.com/features/diabetic-diet-6-foods-control-blood-sugar" target="_hplink">cause blood sugar to spike </a>up as fast as some other kinds of carbohydrates, Marisa Moore, R.D., L.D., a spokeswoman for the Academy of Nutrition and Dietetics (formerly the American Dietetic Association) explained to WebMD. Plus, it maintains satiety and keeps you from feeling hungry -- so you'll be less likely to overeat and gain weight, Moore explained.

  • Short Spurts Of Exercise

    Just a half-hour of intense exercise a week can help with your <a href="http://yourlife.usatoday.com/fitness-food/exercise/story/2011-12-17/Brief-intense-exercise-lowers-blood-sugar-study-finds/52012690/1" target="_hplink">blood sugar levels</a>, <em>USA Today</em> reported. The finding, published last year in the <em>Journal of Applied Physiology</em>, showed that these mini intense exercise sessions <a href="http://yourlife.usatoday.com/fitness-food/exercise/story/2011-12-17/Brief-intense-exercise-lowers-blood-sugar-study-finds/52012690/1" target="_hplink">improved the body's insulin use</a> and, in effect, lowered blood sugar levels among the study participants with Type 2 diabetes.

  • Chow Down On Raisins

    Snacking on <a href="http://www.medicalnewstoday.com/articles/247222.php" target="_hplink">raisins every day</a> could help to keep blood sugar levels from spiking after a meal, Medical News Today reported. The study, presented at the American Diabetes Association's 72nd Annual Scientific Session (and received funding support from the California Raisin Marketing Board), showed that eating the tart snack three times a day for 12 weeks was linked with this <a href="http://www.medicalnewstoday.com/articles/247222.php" target="_hplink">blood sugar benefit</a>, compared with eating other, non-fruit/vegetable snacks, according to Medical News Today.

  • Laugh It Up

    Guffawing after you've eaten could help to keep <a href="http://care.diabetesjournals.org/content/26/5/1651.full" target="_hplink">blood sugar from skyrocketing</a>, according to a <em>Diabetes Care</em> study. Researchers subjected study participants with Type 2 diabetes to a boring lecture after their meal one day, and then a comedy show (where they were asked to rate <a href="http://diabetes.webmd.com/news/20030528/rx-for-diabetes-laughter" target="_hplink">how much they laughed</a>) after their meal on a second day. The participants had their blood sugar levels taken before their meals, as well as two hours after, WebMD reported. The researchers found that the participants' <a href="http://care.diabetesjournals.org/content/26/5/1651.full" target="_hplink">blood sugar levels</a> did not increase as much after the comedy show, as they did after the boring lecture. The finding "suggests the importance of daily opportunities for laughter in patients with diabetes," the researchers wrote.

  • How to Lower Your Blood Sugar

    You can stay healthy despite diabetes with these strategies for keeping your blood sugar controlled.