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What Is the Outcome of Prediabetes?

Prediabetes does not lead inevitably to diabetes. Despite the name, many people with this metabolic disorder are able to reverse their condition.

Doctors are increasingly diagnosing people with prediabetes. These individuals have slightly elevated blood sugar levels that don’t yet meet the criteria for frank diabetes. Some studies have used as their criteria fasting blood glucose between 100 and 124 mg/dL.

How Is Prediabetes Diagnosed?

A blood test called hemoglobin A1C or HbA1c measures glucose in blood over a three-month time period. When the number is consistently over 6.5%, the physician diagnoses the patient with diabetes. Someone with an HbA1c between 5.7% and 6.4% has prediabetes.

Does It Always Lead to Diabetes?

Doctors have assumed that such a diagnosis inevitably means the person will develop diabetes. However, a Swedish study showed that this is not always the case (Journal of Internal Medicine, online June 4, 2019).

In fact, a group of 918 individuals who were 60 years old or older had blood sugar in that gray zone. Of that group, 13 percent went on to develop diabetes. An additional 22 percent saw their blood sugar drop to normal. The rest stayed in the prediabetes category. While this still conveys some risk, it is not quite as dangerous as diabetes.

The lead author noted:

“Lifestyle changes such as weight management or blood pressure control may help stop prediabetes from progressing.”

Will Vitamin D Help Prevent Progression?

Researchers are interested in ways to keep this condition from progressing to outright diabetes. People with low levels of vitamin D circulating in their bloodstreams seem more susceptible to prediabetes. As a result, scientists wonder if giving people vitamin D supplements could reverse the problem.

Previous Study in India Suggests Benefit:

A study from India suggested that those people who have low levels of vitamin D might be able to reverse prediabetes with vitamin D and calcium supplements (Diabetes Research and Clinical Practice, March 2014). Investigators randomly assigned 125 subjects with prediabetes to receive either vitamin D plus calcium or calcium alone.

Half the volunteers took vitamin D3 in doses of 60,000 International Units once weekly for eight weeks. People getting vitamin D were significantly less likely to have diabetes at the end of two years than those taking calcium alone. Although the study was small, it suggested that vitamin D supplements might reduce insulin resistance and improve blood sugar levels in people with prediabetes.

Meta-analysis Looks at Multiple Studies:

Scientists need to follow up this type of interesting research to see how well it holds up. Subsequently, a systematic review of ten randomized controlled trials found that vitamin D supplementation reduced fasting blood sugar and HbA1c (Diabetic Medicine, March 2016).

However, the investigators concluded:

“No beneficial effect of vitamin D in improving insulin resistance was identified.”

Consequently, people with elevated HbA1c measurements may want to try taking vitamin D3 supplements if their blood levels are low. They should not count on this to reverse prediabetes, however.

Most Recent Research on Vitamin D to Reverse Prediabetes Is Promising:

A study published in the Annals of Internal Medicine (Feb. 7, 2023) reviewed data from three randomized clinical trials. People who had been diagnosed with prediabetes took vitamin D supplements or placebo. There were roughly 2,000 volunteers in each group.

Those individuals taking high-dose vitamin D supplements were less likely to be diagnosed with type 2 diabetes after three years. The optimal effect occurred in people taking 4,000 IU per day. Participants who maintained 25 hydroxyvitamin D blood levels of at least 50 ng/ml reduced their three-year relative risk of developing diabetes by 76%. That’s an absolute risk reduction of 18% over three years.

The Recommended Dietary Allowance for vitamin D is much lower than the amount these studies used. In fact, a daily dose of 4,000 IU is right at the top of the safe range. The Food and Nutrition Board has established that as the Tolerable Upper Intake Level for adults in the US.

Other Approaches to Warding Off Diabetes:

Maximize Magnesium:

Research suggests several possible options for keeping people diagnosed with prediabetes from actually developing diabetes. As with vitamin D, people who have low circulating levels of magnesium may be at greater risk for prediabetes (Diabetologia, May 2017). People who consume the most magnesium in their daily diets are 15 percent less likely to develop type 2 diabetes (Diabetes Care, Dec. 2017). We don’t know whether those who take supplements also benefit.

Lose Weight:

Perhaps the most promising approach is simple in concept, but difficult to accomplish. Scientists have found that people who lose weight can keep their prediabetes from progressing (Diabetic Medicine, March 2019).

Consider Taking Citrus Flavonoids:

Beyond that, a single randomized controlled trial of citrus flavonoids (Eriomen®) found that some people taking this supplement were able to reverse their metabolic condition (Phytotherapy Research, online June 11, 2019). Scientists need to do more research to confirm whether this herbal supplement is truly effective.

Contemplate Cinnamon:

Research suggests that compounds in cinnamon can help reverse prediabetes. It is important to select the appropriate cinnamon, as there are several species that vary in their activity. Cassia cinnamon (the most common type on the spice shelf) appears to be quite effective at helping control blood sugar, but it may also contain coumarin. Although this compound occurs naturally in the bark of the cinnamon tree, it can harm the liver if ingested in significant quantities. Ceylon cinnamon or a water extract of cassia cinnamon is safer.

We heard from a reader using cinnamon to try to reverse prediabetes.

Q. I have prediabetes. Although I did everything my doctor told me, nothing worked very well. Following a suggestion on your website, I tried a cinnamon supplement (Cinnulin PF). It really helps! My cravings have gone down significantly and I’ve been losing a little weight.

A. Cinnamon can help with blood sugar control. A controlled trial found that people with prediabetes had lower fasting blood sugar measurements after taking cinnamon for three months (Journal of the Endocrine Society, July 21, 2020). Readers who would like to learn more about using cinnamon to lower blood sugar, cholesterol and triglycerides may be interested in our book, Spice Up Your Health: How Everyday Herbs & Spices Can Lengthen & Strengthen Your Life.

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About the Author
Terry Graedon, PhD, is a medical anthropologist and co-host of The People’s Pharmacy radio show, co-author of The People’s Pharmacy syndicated newspaper columns and numerous books, and co-founder of The People’s Pharmacy website. Terry taught in the Duke University School of Nursing and was an adjunct assistant professor in the Department of Anthropology. She is a Fellow of the Society of Applied Anthropology. Terry is one of the country's leading authorities on the science behind folk remedies..
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