MADRID — For people at risk of type 2 diabetes, restricting eating to eight hours a day, whether that time is early in the morning or late at night, helps control blood sugar levels, according to a time-restricted eating (TRE) study presented at the 2024 Annual Meeting of the European Association for the Study of Diabetes (EASD).
The study looked at altering the time of day of an eight-hour eating window, along with a strictly controlled diet, and found that eight hours of TRE, whether early in the morning or late at night, significantly improved time spent within the normal daily blood glucose range and blood glucose variability.
“While we couldn't show any difference in terms of whether early or late TRE is more effective, we could show a benefit to time-restricted eating within eight hours per day,” study leader Kelly Bowden-Davis, MSc, PhD, of Manchester Metropolitan University, Manchester, UK, said in announcing the study. “It doesn't matter when you restrict your diet, but our research shows that restricting your diet to an eight-hour window has an effect on blood sugar control in people at risk of type 2 diabetes.”
The researchers added that effects were seen after just three days, “demonstrating a therapeutic benefit in adults at risk of type 2 diabetes and warranting longer-term investigation.”
The study investigated the effects of shifting the TRE window from early morning (8am-4pm) to late night (12pm-8pm) in people at risk of developing type 2 diabetes due to a sedentary lifestyle and unhealthy diet.
Previous studies have shown that TRE, which restricts when you eat rather than what you eat, can improve insulin sensitivity and A1c in people at risk for type 2 diabetes.
However, Bowden-Davies noted that the impact of TRE on blood glucose variability is unknown. Previous studies have attributed the positive effects of TRE to reduced energy intake, but this study presented a diet that matched energy intake with energy expenditure, taking into account gender, age, weight, height and activity level, a so-called “eucalorie” diet.
“Some research groups have realized that manipulating the time of your meals can help you better align with your circadian rhythm and improve whole-body insulin sensitivity and blood glucose variability,” Borden-Davis explains. “Eating in the morning may help you better align with your circadian rhythm. [with circadian rhythms] This leads to significant improvements in blood sugar control.”
3-Day TRE Plan Blood sugar control
In a crossover study design, all 15 participants were randomly assigned to follow either the early or late TRE regimen with a 7-day washout period in between. The mean body mass index (BMI) of participants was 27.7 kg/m.2The average waist circumference was 73 cm, and they were physically inactive and had an unhealthy diet.
“The participants had good blood sugar control, as they were normoglycemic, but because they were overweight and obese they are likely at risk of developing type 2 diabetes,” Borden-Davis noted.
Before the TRE period, participants provided the researchers with a food record. If they started early TRE, they would transition to late TRE after a washout period, and vice versa, she explained.
Continuous glucose monitoring (FreeStyle Libre 2, Abbott Laboratories) was performed throughout the study to assess daily time spent in euglycemia (3.9-7.8 mmol/L) and to provide markers of glycemic variability, including mean absolute glucose levels, coefficient of variation, and mean amplitude of glycemic variability. Blood samples were taken both before and after the TRE period, biochemical measurements were performed, and anthropometric measurements were also taken.
Participants were nine women, with a mean age of 52 years and a BMI of 28 kg/m.2A1c The level was 37.9 mmol/mol (5.6%). They tended to snack over a 14-hour or more daily meal window (habitual eating). They were assigned to two different study eating patterns over a three-day period: early or late., These findings were then compared to those of participants who continued their habitual eating habits.
Participants were provided with a standardized diet that was calorically equivalent. [50% carbohydrates, 30% fat, and 20% protein] During the TRE period, subjects ate as they normally would (i.e., whatever they wanted, however they wanted), whereas outside the TRE period, subjects ate as they normally would (i.e., whatever they wanted).
No changes were seen in the biochemical markers assessed. “This is not surprising given that they only underwent TRE for three days,” Borden-Davis said. “Across the two interventions, we saw a weight loss of about 1.1 kg after just three days of TRE,” she reported.
Regarding early versus late TRE therapy, she added, “we saw no advantage.” [no significant differences in glycemic control] Fast TRE is superior to slow TRE, but benefits were seen with limiting eating time to eight hours per day, so both conditions [early and late TRE regimens] It has been effective in controlling blood sugar.
Glycemic control variables were also reduced during TRE therapy compared with habitual eating (≥14 h/day), with a significant increase in time spent within the normoglycemic range by an average of 3.3%, a decrease in mean absolute blood glucose value by 0.6 mmol/L, a decrease in coefficient of variation by 2.6%, and a decrease in mean amplitude of glycemic fluctuation by 0.4 mmol/L.
“That's pretty amazing in three days,” Borden-Davis noted.
She added that although these data are an interim analysis, “these are encouraging results in that participants saw an improvement in their glycemic control and glycemic variability, which are risk factors not only for the development of type 2 diabetes but also for microvascular complications. We also saw an improvement in time in range in terms of tight glycemic control.”
“Even over three days, there were small, subtle differences that would not be clinically relevant, but this is not a clinical cohort. The results were statistically significant and the data are promising, suggesting actionable interventions that could be applied to different populations,” she said, adding that changes in TRE timing over longer time periods could indicate changes in people at risk for type 2 diabetes who do not have disrupted circadian rhythms.
The session was moderated by Dr. Lutgarda Bozzetto, MD, University of Naples Federico II, Naples, Italy. Medscape Medical News“This is a hot topic right now, but the finding that the time of day when dieting occurs makes no difference suggests that the hormonal flux and cycles involved in blood sugar control are not as strong or sensitive in people at risk for diabetes.”
Continuous glucose monitors can be used to check blood glucose levels after meals, which “could be a powerful force in directing behavior change,” Bozzetto said.
Abbott Laboratories provided funding for the continuous glucose monitoring. Neither Borden Davis nor Bozzetto disclosed any other relevant financial information.
