Time-Restricted Eating Improves Glucose Control for Patients With Type 2 Diabetes

Following a time-restricted eating (TRE) protocol shows promising beneficial metabolic effects in adults with type 2 diabetes (T2D), according to research published in Diabetologia.

TRE was linked with decreased 24-hour glucose levels and weight loss in some participants.

The TRE protocol limits food intake to a maximum 10-hour window. The strategy is intended to improve metabolic health by restoring the cycle of daytime eating and prolonging the overnight fast. This prolonged fast may improve insulin sensitivity due to an increased need to replenish nutrient storage.

Previous research demonstrated that TRE leads to promising metabolic changes in people with obesity, including increased fat burning, decreased blood sugar levels, and improved insulin sensitivity. However, the effects of TRE on glucose homeostasis in individuals with T2D are unclear.

To investigate the effects of TRE on hepatic glycogen levels and insulin sensitivity in individuals with T2D, researchers conducted a study including 14 patients with T2D. The participants were between the ages of 50 and 75 and had a body mass index (BMI) 25 kg/m2. The study included 2 intervention periods of 3 weeks, TRE and control. These periods were separated by a wash-out period of at least 4 weeks.

At the start of each intervention, participants had their body weight measured and were fitted with a continuous glucose monitoring (CGM) device which measured their blood sugar level every 15 minutes. Patients were instructed to keep to their normal sleep patterns and physical activity, and to try to maintain a stable weight.

Food and sleep diaries completed during the first intervention were used to ensure that diet during the second period was similar.

During the TRE period, participants were instructed to consume their normal diet within a 10-hour window during the daytime. Participants had to complete their food intake no later than 6 pm.

Outside of the TRE time window, participants were allowed to drink water, plain tea, black coffee, or zero-calorie soft drinks, in moderation.

During the control period, volunteers were instructed to spread their normal food intake over at least 14 hours. No other restrictions applied.

Researchers found that the eating window for TRE averaged 9.1 hours compared to 13.4 hours in control. Sleep-wake patterns were similar in each case, with mean sleep durations of 8.1 hours and 8.0 hours for TRE and control periods, respectively.

Mean body mass was found to be comparable at the start of both TRE and control. However, a small but statistically significant weight loss occurred in response to TRE, despite patients being instructed to remain weight stable. No weight loss was observed during control.

Researchers found that TRE decreased 24-hour glucose levels, primarily as a result of lower nocturnal blood sugar. The average time spent with blood glucose in the normal range increased to 15.1 hours during TRE compared with 12.2 hours during the control phase.

TRE was also found to lower overnight fasting glucose and decrease time spent in the high glucose range.

Morning fasting glucose was observed to be consistently lower among the TRE group than those on the control diet, which the authors suggest may be the result of lasting changes in nocturnal glucose control.

Time spent in hypoglycemia was not significantly increased by TRE. No serious adverse effects were reported, demonstrating that an eating window of approximately 10 hours is a safe and effective lifestyle intervention for adults with T2D.

Approximately halfway through each intervention, researchers assessed liver glycogen levels in the morning following the 10-hour and 14-hour night-time fast period. At the end of each study period, liver glycogen levels were measured again after an 11-hour fast for both TRE and the control phase.

In both cases, liver glycogen did not differ significantly between TRE and the control phase. Additionally, an analysis of liver fats showed no difference in their quantity or composition between interventions.

This study did not show that TRE protocol had any effect on insulin sensitivity. However, previous research using much shorter 6-hour periods of food intake demonstrated an effect on insulin sensitivity.

However, the researchers felt that the longer fasting period was unrealistic to incorporate into the daily lifestyle of patients with T2D.

“Future studies will be needed to reveal whether the duration of the fasting period is indeed crucial in determining positive effects on insulin sensitivity,” said the authors. They propose that the mechanisms involved in the effects and their implications should be investigated further, with focus on studying nocturnal glucose metabolism in more detail.

Overall, the findings suggest that the 10-hour eating window is a safe and effective lifestyle intervention for adults with type 2 diabetes.

“A daytime 10 h TRE regimen for 3 weeks decreases glucose levels and prolongs the time spent in the normal blood sugar range in adults with T2D as compared with spreading daily food intake over at least 14 h. These data highlight the potential benefit of TRE in T2D,” concluded the authors.

“Since our TRE protocol was feasible and safe, and resulted in improved 24 h glucose levels, it would be interesting to examine the impact of 10 h TRE on glucose regulation and insulin sensitivity in type 2 diabetes in the long term to address the clinical relevance of TRE,” they added.

The study had some limitations, including its relatively short duration. Additionally, some but not all participants were on glucose-lowering medication, which the authors suggest may have caused TRE to have less effect.

However, the authors argue that the 3-week intervention period had been found to be long enough to affect the variable being analyzed. They also highlight that they only recruiting volunteers who were not on medication would have reduced the study’s relevance to the general T2D population.

Reference

Andriessen C, Fealy C E, Veelen A, et al. Three weeks of time-restricted eating improves glucose homeostasis in adults with type 2 diabetes but does not improve insulin sensitivity: a randomised crossover trial. Diabetologia. Published online July 25, 2022. doi:10.1007/s00125-022-05752-z