People with type-II diabetes who drank the fermented tea drink kombucha for four weeks had lower fasting blood glucose levels compared to when they consumed a similar-tasting placebo beverage, according to results from a clinical trial conducted by researchers at Georgetown University’s School of Health, the University of Nebraska-Lincoln and MedStar Health. This finding, from a pilot 12-person feasibility trial, points to the potential for a dietary intervention that could help lower blood sugar levels in people with diabetes and also establishes the basis for a larger trial to confirm and expand upon these results.

This finding was reported in Frontiers in Nutrition on August 1, 2023.

Kombucha is a tea fermented with bacteria and yeasts and was consumed as early as 200 B.C. in China, but it did not become popular in the U.S. until the 1990s. Its popularity has been bolstered by anecdotal claims of improved immunity and energy and reductions in food cravings and inflammation, but proof of these benefits has been limited.

“Some laboratory and rodent studies of kombucha have shown promise and one small study in people without diabetes showed kombucha lowered blood sugar, but to our knowledge this is the first clinical trial examining effects of kombucha in people with diabetes,” says study author Dan Merenstein, M.D., professor of Human Sciences in Georgetown’s School of Health and professor of family medicine at Georgetown University School of Medicine. “A lot more research needs to be done but this is very promising.”

Merenstein continued, “A strength of our trial was that we didn’t tell people what to eat because we used a crossover design that limited the effects of any variability in a person’s diet.”

The crossover design had one group of people drinking about eight ounces of kombucha or placebo beverage daily for four weeks and then after a two-month period to ‘wash out’ the biological effects of the beverages, the kombucha and placebo were swapped between groups with another four weeks of drinking the beverages. Neither group was told which drink they were receiving at the time.

Kombucha appeared to lower average fasting blood glucose levels after four weeks from 164 to 116 milligrams per deciliter while the difference after four weeks with the placebo was not statistically significant. Guidelines from the American Diabetes Association recommended blood sugar levels before meals should be between 70 to 130 milligrams per deciliter.

The researchers also looked at the makeup of fermenting micro-organisms in kombucha to determine which ingredients might be the most active. They found that the beverage was mainly comprised of lactic acid bacteria, acetic acid bacteria, and a form of yeast called Dekkera, with each microbe present in about equal measure; the finding was confirmed with RNA gene sequencing.

The kombucha used in this study was produced by Craft Kombucha, a commercial manufacturer in the Washington, DC, area. It has been re-branded as Brindle Boxer Kombucha.

“Different studies of different brands of kombucha by different manufacturers reveal slightly different microbial mixtures and abundances,” says Robert Hutkins, Ph.D., University of Nebraska-Lincoln and the study’s senior author. “However, the major bacteria and yeasts are highly reproducible and likely to be functionally similar between brands and batches, which was reassuring for our trial.”

“An estimated 96 million Americans have pre-diabetes — and diabetes itself is the eighth leading cause of death in the U.S. as well as being a major risk factor for heart disease, stroke and kidney failure,” says Chagai Mendelson, M.D., lead author who was working in Merenstein’s lab at Georgetown while completing his residency at MedStar Health. “We were able to provide preliminary evidence that a common drink could have an effect on diabetes. We hope that a much larger trial, using the lessons we learned in this trial, could be undertaken to give a more definitive answer to the effectiveness of kombucha in reducing blood glucose levels, and hence prevent or help treat type-II diabetes.”

Conventional wisdom holds that storing fat around your belly puts you at increased risk for type 2 diabetes. But surprising new findings from the University of Virginia School of Medicine suggest that naturally occurring variations in our genes can lead some people to store fat at the waist but also protect them from diabetes.

The unexpected discovery provides a more nuanced view of the role of obesity in diabetes and related health conditions. It also could pave the way for more personalized medicine – treatments tailored to the individual. For example, doctors might prioritize weight loss for patients whose genes put them at increased risk but place less emphasis on it for patients with protective gene variants, the researchers say.

“There is a growing body of evidence for metabolically healthy obesity. In this condition, people who would normally be at risk for cardiovascular diseases and diabetes because they are obese are actually protected from adverse effects of their obesity. In our study, we found a genetic link that may explain how this occurs in certain individuals,” said researcher Mete Civelek, PhD, of UVA’s Center for Public Health Genomics. “Understanding various forms of obesity is important to tailor treatments for individuals who are at high risk for adverse effects of obesity.”

As medicine grows more sophisticated, understanding the role of naturally occurring gene variations will play an important role in ensuring patients get the best, most tailored treatments. The new work by Civelek and his team, for example, indicates that variants can simultaneously predispose some people to store fat at the abdomen – thought to put them at increased risk for a cluster of health problems called metabolic syndrome – while also protecting them from type 2 diabetes. (Metabolic syndrome raises the risk for diabetes, stroke and other serious health issues.)

One of the metrics doctors use to determine if a patient has metabolic syndrome is abdominal obesity. This is often calculated by comparing the patient’s waist and hip measurements. But Civelek’s research suggest that, for at least some patients, it may not be that simple. In the future, doctors may want to check a patient’s genes to determine how to best guide the person down the road to good health. 

“We found that among the hundreds of regions in our genomes which increase our propensity to accumulate excess fat in our abdomens, there are five which have an unexpected role,” said Yonathan Aberra, the lead author of the study and a PhD candidate at UVA’s Department of Biomedical Engineering, a joint program of the School of Medicine and School of Engineering. “To our surprise, these five regions decrease an individual’s risk for type 2 diabetes.”

In addition to producing surprising findings, Civelek’s research provides important new tools for his fellow researchers seeking to understand the complexities of gene variations. The sophisticated approach Civelek and his collaborators developed to identify the relevant variants and their potential effects will be useful for future research into metabolic syndrome and other conditions.

The tools could also prove invaluable in the development of new and better treatments for metabolic syndrome, the scientists say.

“We now need to expand our studies in more women and people from different genetic ancestries to identify even more genes that underlie the metabolically health obesity phenomenon,” Civelek said. “We plan to build on our findings to perform more experiments to potentially identify a therapeutic target.” 

Losing weight is often a goal for people with type 2 diabetes, which is strongly associated with being overweight or obese. However, it hasn’t been clear what dieting strategy works best for people with this metabolic disorder.

A new randomized controlled study of people with type 2 diabetes showed that study participants who restricted eating to between noon and 8 p.m. daily lost more weight than those who reduced their overall calorie intake by counting calories. Both dieting strategies produced similar improvements in blood sugar levels.

“Many people find counting calories very hard to stick to in the long term, but our study shows that watching the clock may offer a simple way to decrease calories and lose weight,” said Vicky Pavlou, RDN, a doctoral student at the University of Illinois at Chicago who performed the new research. “Although time-restricted eating is becoming increasingly popular, no other studies have looked at an eight-hour eating window in people with type 2 diabetes.”

Pavlou will present the findings at NUTRITION 2023, the annual flagship meeting of the American Society for Nutrition held July 22-25 in Boston.

Eating only during an eight-hour window has been studied previously for people with obesity. However, the researchers, led by Krista Varady, a professor of nutrition at the University of Illinois at Chicago, wanted to find out if this strategy could be helpful for people with type 2 diabetes.

The study included a group of 75 racially and ethnically diverse people between 18 to 80 years old with obesity and type 2 diabetes. Participants were placed into one of three groups: time-restricted eating, calorie restriction, or control. The people in the time-restricted eating group ate only between noon and 8 p.m. while the calorie restriction group could eat at any time of the day but counted their calories on the MyFitnessPal mobile app with a goal of reducing their caloric intake by 25% of their maintenance calories — the calories needed to maintain their current weight. The control group continued eating their normal diet.

Over the course of the six-month study, the researchers found that the people on the time-restricted eating diet lost 3.55% of their body weight relative to the control group. This would be the equivalent of a person weighing 275 pounds losing just under 10 pounds. The calorie restriction group did not lose any weight relative to the control group. Compared to the control group, blood sugar (HbA1C) levels decreased in both the time-restricted group (-.91%) and the calorie restriction group (-.95%).

The researchers also assessed whether these diet strategies improved cardiometabolic risk factors, but the weight loss achieved with the time-restricted eating did not reach the 5% mark typically necessary for improvement in these factors. Also, the study participants were taking cholesterol and blood pressure medications, which makes it difficult to observe improvements in cardiometabolic risk factors. 

“Our study shows that time-restricted eating can be a good alternative for those with type 2 diabetes who want to lose weight and improve their blood sugar,” said Pavlou. “However, there are multiple types of medications for those with type 2 diabetes, some of which can cause low blood sugar and some that need to be taken with food. Therefore, it is important to work closely with a dietitian or doctor when implementing this dieting approach.”

The discovery of insulin has saved the lives of millions of people with diabetes worldwide, but little is known about the first step of insulin synthesis.

Researchers at the University of Michigan have uncovered part of this mystery. Examining messenger RNAs involved in the production of insulin in fruit flies, they found that a chemical tag on the mRNA is crucial to translating the insulin mRNA into the protein insulin. The alteration of this chemical tag can affect how much insulin is produced. 

The study, conducted by researchers Daniel Wilinski and Monica Dus, is published in the journal Nature Structural and Molecular Biology.

An organism carries DNA—its genes—in each cell of its bodies. Genes are blocks of information that get transcribed into proteins via another molecule called messenger RNAs. These mRNAs are photocopies of DNA—leaving the original DNA untouched—that ferry this protein information into the cytoplasm of cells, where protein is synthesized. The mRNAs are decorated with small molecules called “tags.” These tags can modify how RNAs function and how proteins are produced.

“I like to think of RNA as a Christmas tree,” said Wilinski, a postdoctoral researcher in Dus’ lab in the U-M Department of Molecular, Cellular and Developmental Biology. “Christmas trees are beautiful in the wilderness, but when you bring them inside and put ornaments on them, that decoration is what makes you feel like the tree is part of the season. Same thing with RNA. These decorations on RNA really enhance the way RNA is regulated.”

Studying insulin production in humans or mammals is difficult. In humans, the pancreas is situated behind the liver. It doesn’t regenerate well, and it can’t be sampled in live subjects. But in flies, their insulin cells are actually in their brains, function like neurons, and are physically accessible to researchers. In fruit flies, the researchers looked at a tag called RNA N-6 adenosine methylation, or m6A.

To study the m6A tag, the researchers first identified the RNAs that have the tag. Then they labeled insulin cells with a fluorescent molecule, and used confocal microscopy to visualize how much insulin is produced by the insulin cell. They did this under two conditions: first, they knocked out the m6A enzyme, responsible for decorating the mRNA with m6A tags, in insulin cells. Second, they removed the m6A tags by using CRISPR, a technology used to edit DNA, to mutate the modified As.

In both cases, the flies’ ability to produce insulin was greatly reduced.

“We found that this photocopy of the DNA for insulin, this mRNA, had a specific tag that, when it is present, a ton of the insulin hormone is made,” said Dus, associate professor of molecular, cellular and developmental biology. “But without the signal, flies had much less insulin and developed hallmarks of diabetes.”

This chemical tag is conserved—or unchanged—in fish, mice and humans.

“So it’s likely that insulin production is also regulated through this kind of mechanism in humans,” Wilinski said. “There is an obesity and diabetes epidemic not just in the United States, but across the world. Our finding is another bit of evidence about how this disease happens.”

Dus says the discovery fleshes out the understanding of the biology of insulin and the physiology of diseases of energy homeostasis. Low levels of chemical tags have been observed in people with Type 2 diabetes. Restoring the levels of these tags may also help with combating diabetes and metabolic disease, she says. 

“We have known about insulin as a treatment for a hundred years. We have discovered so much about how insulin is made,” Dus said. “But we know so little about the very basic molecular biology of insulin and how it is regulated. That’s why I think this work is important—it refocuses on insulin, the gene and all the things we still have to discover about it.”