Early Time-Restricted Eating Cut Blood Sugar Fluctuations in Prediabetes

CHICAGO – Just 1 week of early time-restricted feeding (eTRF) cut fluctuations in blood sugar levels, and reduced the time that blood sugar was elevated, in people with prediabetes and a high BMI, according to the TRIO study.

The difference in the mean amplitude of glycemic excursion (MAGE) — the standard for assessing short-term within-day glycemic variability — was 2.9 mmol/L with a usual feeding pattern versus 2.4 mmol/L with eTRF, and the difference was statistically significant (P=0.001), reported Joanne Bruno, MD, PhD, of NYU Langone Health in New York City.

At a press conference at ENDO 2023, the annual meeting of the Endocrine Society, Bruno noted that eTRF “improves glycemia by reducing blood sugar fluctuation as well as the time that the blood sugar is elevated above normal levels,” Bruno said “These effects are independent of weight loss. Based on these data, early time restricted feeding may be a helpful dietary strategy for diabetes prevention.”

She explained that eTRF is a type of intermittent fasting where food intake is restricted to the first 6-8 hours of the day. “We defined early time-restricted feeding as an eating window from 8 a.m. to 4 p.m. with 80% of calories consumed prior to 1 p.m.,” she said. “We found that just 1 week of early-time restricted feeding reduces fluctuations in blood sugar levels, and reduces the time that the blood sugar is elevated.”

While TRIO participants achieved the result in the context of a supervised feeding study, the results may be generalizable.”There have been multiple real-world studies looking at time restricted feeding, not specifically early time-restricted feeding, that have demonstrated feasibility of some of these protocols,” she told MedPage Today.

TRIO was a randomized, 6-day isocaloric, crossover study that compared eTRF to usual feeding in people with prediabetes and a BMI >28. The 10 participants were about age 58, and evenly divided between men and women. Eight of 10 participants were Black. Overall BMI was 37.29, and the mean HbA1c was 5.79%. Their initial high-sensitive C-reactive protein (hsCRP) was 0.66.

The 10 people were randomized 1:1 with either 1 week of an eTRF diet, or 1 week of a usual feeding diet, at which point they crossed over to the alternate arm of the study for the subsequent week, Bruno said.

Measurements were taken at baseline, day 7, and day 14. TRIO’s primary endpoints were change in glycemic variation by mean amplitude of glycemic excursion in the TRF arm relative to the control arm, along with change in inflammatory plasma marker concentrations (sRAGE and hsCRP) in the TRF arm relative to the control arm, all between those time points. Participants wore continuous glucose monitors for the study.

The researchers reported the following for eTRF versus usual feeding diet:

• Mean glucose: 5.4 vs 5.2 mmol/L
• Time in range (blood glucose 70-180%): 96% vs 93%
• hsCRP: 1.12 at crossover; 1.02 final

Bruno pointed out that “this was a weight-neutral study, and all of the food was provided for our participants to consume throughout the duration of the study. Their diets were engineered to match their home diet and food preferences, as well as to ensure that they would consume enough calories that they would maintain their weight throughout the study.”

She acknowledged that more real-world data were need, but added that participants were surveyed about hunger, satiety, and fullness at baseline and “after their experience on each of the two arms…and there were no significant differences between…baseline to any of the 2 weeks, or between the 2 weeks of the study,” Bruno said. “So I do think that it is possible for people to do this in the real world.” She called it “promising that the participants “did feel that they weren’t especially hungry after their early-eating diet and they were very satisfied with the meals that they did receive.”

Joseph Henske, MD, of the University of Arkansas for Medical Sciences in Little Rock, told MedPage Today that the study “had interesting results in this prediabetic population.”

However, it was a “very small study,” said Henske, who was not involved in the research. “I would think we would need larger confirmatory studies for this type of restricted feeding to gain wide appeal. It would also be helpful to see if this type of program could be helpful in people who were diabetic as well,” he said.